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breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.06076">arXiv:2410.06076</a> <span> [<a href="https://arxiv.org/pdf/2410.06076">pdf</a>, <a href="https://arxiv.org/ps/2410.06076">ps</a>, <a href="https://arxiv.org/format/2410.06076">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202449861">10.1051/0004-6361/202449861 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterising the stellar differential rotation based on largest-spot statistics from ground-based photometry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Tuomi%2C+M">Mikko Tuomi</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Henry%2C+G+W">Gregory W. Henry</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.06076v1-abstract-short" style="display: inline;"> Stellar spot distribution has consequences on the observable periodic signals in long-time baseline ground-based photometry. We model the statistics of the dominating spots of two young and active Solar-type stars, V889 Her and LQ Hya, in order to obtain information on the underlying spot distribution, rotation of the star, as well as the orientation of the stellar axis of spin. By calculating e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06076v1-abstract-full').style.display = 'inline'; document.getElementById('2410.06076v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.06076v1-abstract-full" style="display: none;"> Stellar spot distribution has consequences on the observable periodic signals in long-time baseline ground-based photometry. We model the statistics of the dominating spots of two young and active Solar-type stars, V889 Her and LQ Hya, in order to obtain information on the underlying spot distribution, rotation of the star, as well as the orientation of the stellar axis of spin. By calculating estimates for spot-induced periodicities in independent subsets of photometric data, we obtain statistics based on the dominating spots in each subset, giving rise to largest-spot statistics accounting for stellar geometry and rotation, including differential rotation. Our simple statistical models are able to reproduce the observed distribution of photometric signals rather well. This also enables us to estimate the dependence of angular velocity of the spots as a function of latitude. Our results indicate that V889 Her has a non-monotonic differential rotation curve with a maximum angular velocity between latitudes of 37-40 deg and lower angular velocity at the pole than the equator. Our results for LQ Hya indicate that the star rotates much like a rigid body. Furthermore, the results imply that the monotonic Solar differential rotation curve may not be a universal model for other solar-type stars. The non-monotonicity of the differential rotation of V889 Her is commonly produced in magnetohydrodynamic simulations, which indicates that our results are realistic from a theoretical perspective. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.06076v1-abstract-full').style.display = 'none'; document.getElementById('2410.06076v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 7 figures., final submitted version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A, 689, A262 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.01077">arXiv:2410.01077</a> <span> [<a href="https://arxiv.org/pdf/2410.01077">pdf</a>, <a href="https://arxiv.org/format/2410.01077">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> </div> <p class="title is-5 mathjax"> Millikelvin Si-MOSFETs for Quantum Electronics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Yurttag%C3%BCl%2C+N">Nikolai Yurttag眉l</a>, <a href="/search/?searchtype=author&query=Kainlauri%2C+M">Markku Kainlauri</a>, <a href="/search/?searchtype=author&query=Toivonen%2C+J">Jan Toivonen</a>, <a href="/search/?searchtype=author&query=Khadka%2C+S">Sushan Khadka</a>, <a href="/search/?searchtype=author&query=Kanniainen%2C+A">Antti Kanniainen</a>, <a href="/search/?searchtype=author&query=Kumar%2C+A">Arvind Kumar</a>, <a href="/search/?searchtype=author&query=Subero%2C+D">Diego Subero</a>, <a href="/search/?searchtype=author&query=Muhonen%2C+J">Juha Muhonen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.01077v1-abstract-short" style="display: inline;"> Large power consumption of silicon CMOS electronics is a challenge in very-large-scale integrated circuits and a major roadblock to fault-tolerant quantum computation. Matching the power dissipation of Si-MOSFETs to the thermal budget at deep cryogenic temperatures, below 1 K, requires switching performance beyond levels facilitated by currently available CMOS technologies. We have manufactured fu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.01077v1-abstract-full').style.display = 'inline'; document.getElementById('2410.01077v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.01077v1-abstract-full" style="display: none;"> Large power consumption of silicon CMOS electronics is a challenge in very-large-scale integrated circuits and a major roadblock to fault-tolerant quantum computation. Matching the power dissipation of Si-MOSFETs to the thermal budget at deep cryogenic temperatures, below 1 K, requires switching performance beyond levels facilitated by currently available CMOS technologies. We have manufactured fully depleted silicon-on-insulator MOSFETs tailored for overcoming the power dissipation barrier towards sub-1 K applications. With these cryo-optimized transistors we achieve a major milestone of reaching subthreshold swing of 0.3 mV/dec at 420 mK, thereby enabling very-large-scale integration of cryo-CMOS electronics for ultra-low temperature applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.01077v1-abstract-full').style.display = 'none'; document.getElementById('2410.01077v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.02507">arXiv:2406.02507</a> <span> [<a href="https://arxiv.org/pdf/2406.02507">pdf</a>, <a href="https://arxiv.org/format/2406.02507">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Guiding a Diffusion Model with a Bad Version of Itself </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Kynk%C3%A4%C3%A4nniemi%2C+T">Tuomas Kynk盲盲nniemi</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.02507v3-abstract-short" style="display: inline;"> The primary axes of interest in image-generating diffusion models are image quality, the amount of variation in the results, and how well the results align with a given condition, e.g., a class label or a text prompt. The popular classifier-free guidance approach uses an unconditional model to guide a conditional model, leading to simultaneously better prompt alignment and higher-quality images at… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02507v3-abstract-full').style.display = 'inline'; document.getElementById('2406.02507v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.02507v3-abstract-full" style="display: none;"> The primary axes of interest in image-generating diffusion models are image quality, the amount of variation in the results, and how well the results align with a given condition, e.g., a class label or a text prompt. The popular classifier-free guidance approach uses an unconditional model to guide a conditional model, leading to simultaneously better prompt alignment and higher-quality images at the cost of reduced variation. These effects seem inherently entangled, and thus hard to control. We make the surprising observation that it is possible to obtain disentangled control over image quality without compromising the amount of variation by guiding generation using a smaller, less-trained version of the model itself rather than an unconditional model. This leads to significant improvements in ImageNet generation, setting record FIDs of 1.01 for 64x64 and 1.25 for 512x512, using publicly available networks. Furthermore, the method is also applicable to unconditional diffusion models, drastically improving their quality. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.02507v3-abstract-full').style.display = 'none'; document.getElementById('2406.02507v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">NeurIPS 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.07724">arXiv:2404.07724</a> <span> [<a href="https://arxiv.org/pdf/2404.07724">pdf</a>, <a href="https://arxiv.org/format/2404.07724">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Applying Guidance in a Limited Interval Improves Sample and Distribution Quality in Diffusion Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kynk%C3%A4%C3%A4nniemi%2C+T">Tuomas Kynk盲盲nniemi</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.07724v2-abstract-short" style="display: inline;"> Guidance is a crucial technique for extracting the best performance out of image-generating diffusion models. Traditionally, a constant guidance weight has been applied throughout the sampling chain of an image. We show that guidance is clearly harmful toward the beginning of the chain (high noise levels), largely unnecessary toward the end (low noise levels), and only beneficial in the middle. We… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.07724v2-abstract-full').style.display = 'inline'; document.getElementById('2404.07724v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.07724v2-abstract-full" style="display: none;"> Guidance is a crucial technique for extracting the best performance out of image-generating diffusion models. Traditionally, a constant guidance weight has been applied throughout the sampling chain of an image. We show that guidance is clearly harmful toward the beginning of the chain (high noise levels), largely unnecessary toward the end (low noise levels), and only beneficial in the middle. We thus restrict it to a specific range of noise levels, improving both the inference speed and result quality. This limited guidance interval improves the record FID in ImageNet-512 significantly, from 1.81 to 1.40. We show that it is quantitatively and qualitatively beneficial across different sampler parameters, network architectures, and datasets, including the large-scale setting of Stable Diffusion XL. We thus suggest exposing the guidance interval as a hyperparameter in all diffusion models that use guidance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.07724v2-abstract-full').style.display = 'none'; document.getElementById('2404.07724v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">NeurIPS 2024</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2403.08655">arXiv:2403.08655</a> <span> [<a href="https://arxiv.org/pdf/2403.08655">pdf</a>, <a href="https://arxiv.org/ps/2403.08655">ps</a>, <a href="https://arxiv.org/format/2403.08655">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevApplied.22.064048">10.1103/PhysRevApplied.22.064048 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Efficient electronic cooling above 2 K by niobium-based superconducting tunnel junctions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=H%C3%A4tinen%2C+J">J. H盲tinen</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">A. Ronzani</a>, <a href="/search/?searchtype=author&query=Loreto%2C+R+P">R. P. Loreto</a>, <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">E. Mykk盲nen</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">A. Kemppinen</a>, <a href="/search/?searchtype=author&query=Viisanen%2C+K">K. Viisanen</a>, <a href="/search/?searchtype=author&query=Rantanen%2C+T">T. Rantanen</a>, <a href="/search/?searchtype=author&query=Geisor%2C+J">J. Geisor</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Ribeiro%2C+M">M. Ribeiro</a>, <a href="/search/?searchtype=author&query=Kaikkonen%2C+J">J-P. Kaikkonen</a>, <a href="/search/?searchtype=author&query=Prakash%2C+O">O. Prakash</a>, <a href="/search/?searchtype=author&query=Vesterinen%2C+V">V. Vesterinen</a>, <a href="/search/?searchtype=author&query=F%C3%B6rbom%2C+W">W. F枚rbom</a>, <a href="/search/?searchtype=author&query=Mannila%2C+E+T">E. T. Mannila</a>, <a href="/search/?searchtype=author&query=Kervinen%2C+M">M. Kervinen</a>, <a href="/search/?searchtype=author&query=Govenius%2C+J">J. Govenius</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">M. Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2403.08655v3-abstract-short" style="display: inline;"> Replacing the bulky cryoliquid-based cooling stages of cryoenabled instruments by chip-scale refrigeration is envisioned to disruptively reduce the system size similar to microprocessors did for computers. Electronic refrigerators based on superconducting tunnel junctions have been anticipated to provide a solution, but reaching the necessary above the 1-K operation temperature range has remained… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.08655v3-abstract-full').style.display = 'inline'; document.getElementById('2403.08655v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.08655v3-abstract-full" style="display: none;"> Replacing the bulky cryoliquid-based cooling stages of cryoenabled instruments by chip-scale refrigeration is envisioned to disruptively reduce the system size similar to microprocessors did for computers. Electronic refrigerators based on superconducting tunnel junctions have been anticipated to provide a solution, but reaching the necessary above the 1-K operation temperature range has remained a goal out of reach for several decades. We show efficient electronic refrigeration by Al-AlO$_x$-Nb superconducting tunnel junctions starting from bath temperatures above 2 K. The junctions can deliver electronic cooling power up to approximately mW/mm$^2$, which enables us to demonstrate tunnel-current-driven electron temperature reduction from 2.4 K to below 1.6 K (34% relative cooling) against the phonon bath. Our work shows that the key material of integrated superconducting circuits - niobium - enables powerful cryogenic refrigerator technology. This result is a prerequisite for practical cryogenic chip-scale refrigerators and, at the same time, it introduces a new electrothermal tool for quantum heat-transport experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.08655v3-abstract-full').style.display = 'none'; document.getElementById('2403.08655v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 December, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 22, 064048 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04136">arXiv:2312.04136</a> <span> [<a href="https://arxiv.org/pdf/2312.04136">pdf</a>, <a href="https://arxiv.org/format/2312.04136">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> </div> <p class="title is-5 mathjax"> Surface distribution of small-scale magnetic field on the active cool star LQ Hydrae </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.04136v1-abstract-short" style="display: inline;"> It is well known that small-scale magnetism dominates the surface magnetic field topologies of active late-type stars. However, little information is available on the spatial distribution of this key magnetic field component. Here, we take advantage of the recently developed magnetic field diagnostic procedure relying on the magnetic intensification of iron atomic lines in the optical. We extend t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04136v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04136v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04136v1-abstract-full" style="display: none;"> It is well known that small-scale magnetism dominates the surface magnetic field topologies of active late-type stars. However, little information is available on the spatial distribution of this key magnetic field component. Here, we take advantage of the recently developed magnetic field diagnostic procedure relying on the magnetic intensification of iron atomic lines in the optical. We extend this methodology from measuring a single average field strength value to simultaneous Doppler imaging reconstruction of the two-dimensional maps of temperature and magnetic field strength. We applied this novel surface mapping approach to two spectroscopic data sets of the young active Sun-like star LQ Hya. For both epochs, we found a fairly uniform field strength distribution, apart from a latitudinal trend of the field strength increasing from 1.5-2.0 kG at low latitudes to 3.0-3.5 kG, close to the rotational poles. This distribution of the small-scale field does not display a clear correlation with the locations of temperature spots or the global magnetic field structure reconstructed for the same epochs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04136v1-abstract-full').style.display = 'none'; document.getElementById('2312.04136v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7 pages, 6 figures; accepted for publication in A&A</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.02696">arXiv:2312.02696</a> <span> [<a href="https://arxiv.org/pdf/2312.02696">pdf</a>, <a href="https://arxiv.org/format/2312.02696">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Analyzing and Improving the Training Dynamics of Diffusion Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.02696v2-abstract-short" style="display: inline;"> Diffusion models currently dominate the field of data-driven image synthesis with their unparalleled scaling to large datasets. In this paper, we identify and rectify several causes for uneven and ineffective training in the popular ADM diffusion model architecture, without altering its high-level structure. Observing uncontrolled magnitude changes and imbalances in both the network activations an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02696v2-abstract-full').style.display = 'inline'; document.getElementById('2312.02696v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.02696v2-abstract-full" style="display: none;"> Diffusion models currently dominate the field of data-driven image synthesis with their unparalleled scaling to large datasets. In this paper, we identify and rectify several causes for uneven and ineffective training in the popular ADM diffusion model architecture, without altering its high-level structure. Observing uncontrolled magnitude changes and imbalances in both the network activations and weights over the course of training, we redesign the network layers to preserve activation, weight, and update magnitudes on expectation. We find that systematic application of this philosophy eliminates the observed drifts and imbalances, resulting in considerably better networks at equal computational complexity. Our modifications improve the previous record FID of 2.41 in ImageNet-512 synthesis to 1.81, achieved using fast deterministic sampling. As an independent contribution, we present a method for setting the exponential moving average (EMA) parameters post-hoc, i.e., after completing the training run. This allows precise tuning of EMA length without the cost of performing several training runs, and reveals its surprising interactions with network architecture, training time, and guidance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.02696v2-abstract-full').style.display = 'none'; document.getElementById('2312.02696v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 March, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.07838">arXiv:2306.07838</a> <span> [<a href="https://arxiv.org/pdf/2306.07838">pdf</a>, <a href="https://arxiv.org/ps/2306.07838">ps</a>, <a href="https://arxiv.org/format/2306.07838">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Methods for Astrophysics">astro-ph.IM</span> </div> </div> <p class="title is-5 mathjax"> From convective stellar dynamo simulations to Zeeman-Doppler images </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/?searchtype=author&query=Viviani%2C+M">Mariangela Viviani</a>, <a href="/search/?searchtype=author&query=Warnecke%2C+J">J枚rn Warnecke</a>, <a href="/search/?searchtype=author&query=Korpi-Lagg%2C+M+J">Maarit J. Korpi-Lagg</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.07838v2-abstract-short" style="display: inline;"> Zeeman-Doppler imaging (ZDI) is used to reconstruct the surface magnetic field of late-type stars from high resolution spectropolarimetric observations. The results are usually described in terms of characteristics of the field topology, i.e. poloidality vs. toroidality and axi-symmetry vs. non-axisymmetry in addition to the field strength. We want to test how well these characteristics are preser… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.07838v2-abstract-full').style.display = 'inline'; document.getElementById('2306.07838v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.07838v2-abstract-full" style="display: none;"> Zeeman-Doppler imaging (ZDI) is used to reconstruct the surface magnetic field of late-type stars from high resolution spectropolarimetric observations. The results are usually described in terms of characteristics of the field topology, i.e. poloidality vs. toroidality and axi-symmetry vs. non-axisymmetry in addition to the field strength. We want to test how well these characteristics are preserved when applying the ZDI method on simulated data, i.e. how accurately the field topology is preserved and to what extent stellar parameters influence the reconstruction. We use published magnetic field data from direct numerical MHD simulations. These have variable rotation rates, and hence represent different levels of activity, of an otherwise Sun-like setup. Our ZDI reconstruction is based on spherical harmonics expansion. By comparing the original values to those of the reconstructed images, we study the ability to reconstruct the surface magnetic field in terms of various characteristics of the field. The main large-scale features are reasonably well recovered, but the strength of the recovered magnetic field is just a fraction of the original input. The quality of the reconstruction shows clear correlations with the data quality. Furthermore, there are some spurious dependencies between stellar parameters and the characteristics of the field. Our study uncovers some limits of ZDI. Firstly, the recovered field strength will generally be lower than the "real" value as smaller structures with opposite polarities will be blurred in the inversion. Secondly, the axisymmetry is overestimated. The poloidality vs. toroidality is better recovered. The reconstruction works better for a stronger field and faster rotation velocity. Still, the ZDI method works surprisingly well even for a weaker field and slow rotation, provided the data has a high signal-to-noise and good rotation phase coverage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.07838v2-abstract-full').style.display = 'none'; document.getElementById('2306.07838v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 21 figures, A&A, in press, abstract shortened</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.11202">arXiv:2303.11202</a> <span> [<a href="https://arxiv.org/pdf/2303.11202">pdf</a>, <a href="https://arxiv.org/format/2303.11202">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> </div> <p class="title is-5 mathjax"> Effect of ion irradiation on superconducting thin films </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kohop%C3%A4%C3%A4%2C+K">Katja Kohop盲盲</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">Alberto Ronzani</a>, <a href="/search/?searchtype=author&query=Jabdaraghi%2C+R+N">Robab Najafi Jabdaraghi</a>, <a href="/search/?searchtype=author&query=Bera%2C+A">Arijit Bera</a>, <a href="/search/?searchtype=author&query=Ribeiro%2C+M">M谩rio Ribeiro</a>, <a href="/search/?searchtype=author&query=Hazra%2C+D">Dibyendu Hazra</a>, <a href="/search/?searchtype=author&query=Senior%2C+J">Jorden Senior</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Govenius%2C+J">Joonas Govenius</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">Antti Kemppinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.11202v2-abstract-short" style="display: inline;"> We demonstrate ion irradiation by argon or gallium as a wafer-scale post-processing method to increase disorder in superconducting thin films. We study several widely used superconductors, both single-elements and compounds. We show that ion irradiation increases normal-state resistivity in all our films, which is expected to enable tuning their superconducting properties, for example, toward high… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.11202v2-abstract-full').style.display = 'inline'; document.getElementById('2303.11202v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.11202v2-abstract-full" style="display: none;"> We demonstrate ion irradiation by argon or gallium as a wafer-scale post-processing method to increase disorder in superconducting thin films. We study several widely used superconductors, both single-elements and compounds. We show that ion irradiation increases normal-state resistivity in all our films, which is expected to enable tuning their superconducting properties, for example, toward higher kinetic inductance. We observe an increase of superconducting transition temperature for Al and MoSi, and a decrease for Nb, NbN, and TiN. In MoSi, ion irradiation also improves the mixing of the two materials. We demonstrate fabrication of an amorphous and homogeneous film of MoSi with uniform thickness, which is promising, e.g., for superconducting nanowire single-photon detectors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.11202v2-abstract-full').style.display = 'none'; document.getElementById('2303.11202v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2303.01228">arXiv:2303.01228</a> <span> [<a href="https://arxiv.org/pdf/2303.01228">pdf</a>, <a href="https://arxiv.org/ps/2303.01228">ps</a>, <a href="https://arxiv.org/format/2303.01228">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0162409">10.1063/5.0162409 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Thermal resistance in superconducting flip-chip assemblies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=H%C3%A4tinen%2C+J">Joel H盲tinen</a>, <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">Emma Mykk盲nen</a>, <a href="/search/?searchtype=author&query=Viisanen%2C+K">Klaara Viisanen</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">Alberto Ronzani</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">Antti Kemppinen</a>, <a href="/search/?searchtype=author&query=Lehtisyrj%C3%A4%2C+L">Lassi Lehtisyrj盲</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2303.01228v3-abstract-short" style="display: inline;"> Cryogenic microsystems that utilize different 3D integration techniques are being actively developed, e.g., for the needs of quantum technologies. 3D integration can introduce opportunities and challenges to the thermal management of low temperature devices. In this work, we investigate sub-1 K inter-chip thermal resistance of a flip-chip bonded assembly, where two silicon chips are interconnected… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.01228v3-abstract-full').style.display = 'inline'; document.getElementById('2303.01228v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2303.01228v3-abstract-full" style="display: none;"> Cryogenic microsystems that utilize different 3D integration techniques are being actively developed, e.g., for the needs of quantum technologies. 3D integration can introduce opportunities and challenges to the thermal management of low temperature devices. In this work, we investigate sub-1 K inter-chip thermal resistance of a flip-chip bonded assembly, where two silicon chips are interconnected by compression bonding via indium bumps. The total thermal contact area between the chips is 0.306 mm$^2$ and we find that the temperature dependence of the inter-chip thermal resistance follows the power law of $伪T^{-3}$, with $伪= 7.7-15.4$ K$^4$$渭$m$^2$/nW. The $T^{-3}$ relation indicates phononic interfacial thermal resistance, which is supported by the vanishing contribution of the electrons to the thermal conduction, due to the superconducting interconnections. Such a thermal resistance value can introduce a thermalization bottleneck in particular at cryogenic temperatures. This can be detrimental for some applications, yet it can also be harnessed. We provide an example of both cases by estimating the parasitic overheating of a cryogenic flip-chip assembly operated under various heat loads as well as simulate the performance of solid-state junction microrefrigerators utilizing the observed thermal isolation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2303.01228v3-abstract-full').style.display = 'none'; document.getElementById('2303.01228v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 4 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Thermal resistance in superconducting flip-chip assemblies. Appl. Phys. Lett. 1 October 2023; 123 (15): 152202 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.07431">arXiv:2212.07431</a> <span> [<a href="https://arxiv.org/pdf/2212.07431">pdf</a>, <a href="https://arxiv.org/format/2212.07431">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> </div> </div> <p class="title is-5 mathjax"> Simulator-Based Self-Supervision for Learned 3D Tomography Reconstruction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kosomaa%2C+O">Onni Kosomaa</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.07431v2-abstract-short" style="display: inline;"> We propose a deep learning method for 3D volumetric reconstruction in low-dose helical cone-beam computed tomography. Prior machine learning approaches require reference reconstructions computed by another algorithm for training. In contrast, we train our model in a fully self-supervised manner using only noisy 2D X-ray data. This is enabled by incorporating a fast differentiable CT simulator in t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07431v2-abstract-full').style.display = 'inline'; document.getElementById('2212.07431v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.07431v2-abstract-full" style="display: none;"> We propose a deep learning method for 3D volumetric reconstruction in low-dose helical cone-beam computed tomography. Prior machine learning approaches require reference reconstructions computed by another algorithm for training. In contrast, we train our model in a fully self-supervised manner using only noisy 2D X-ray data. This is enabled by incorporating a fast differentiable CT simulator in the training loop. As we do not rely on reference reconstructions, the fidelity of our results is not limited by their potential shortcomings. We evaluate our method on real helical cone-beam projections and simulated phantoms. Our results show significantly higher visual fidelity and better PSNR over techniques that rely on existing reconstructions. When applied to full-dose data, our method produces high-quality results orders of magnitude faster than iterative techniques. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.07431v2-abstract-full').style.display = 'none'; document.getElementById('2212.07431v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.15228">arXiv:2210.15228</a> <span> [<a href="https://arxiv.org/pdf/2210.15228">pdf</a>, <a href="https://arxiv.org/format/2210.15228">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Audio and Speech Processing">eess.AS</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Sound">cs.SD</span> </div> </div> <p class="title is-5 mathjax"> Solving Audio Inverse Problems with a Diffusion Model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Moliner%2C+E">Eloi Moliner</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=V%C3%A4lim%C3%A4ki%2C+V">Vesa V盲lim盲ki</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.15228v3-abstract-short" style="display: inline;"> This paper presents CQT-Diff, a data-driven generative audio model that can, once trained, be used for solving various different audio inverse problems in a problem-agnostic setting. CQT-Diff is a neural diffusion model with an architecture that is carefully constructed to exploit pitch-equivariant symmetries in music. This is achieved by preconditioning the model with an invertible Constant-Q Tra… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.15228v3-abstract-full').style.display = 'inline'; document.getElementById('2210.15228v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.15228v3-abstract-full" style="display: none;"> This paper presents CQT-Diff, a data-driven generative audio model that can, once trained, be used for solving various different audio inverse problems in a problem-agnostic setting. CQT-Diff is a neural diffusion model with an architecture that is carefully constructed to exploit pitch-equivariant symmetries in music. This is achieved by preconditioning the model with an invertible Constant-Q Transform (CQT), whose logarithmically-spaced frequency axis represents pitch equivariance as translation equivariance. The proposed method is evaluated with objective and subjective metrics in three different and varied tasks: audio bandwidth extension, inpainting, and declipping. The results show that CQT-Diff outperforms the compared baselines and ablations in audio bandwidth extension and, without retraining, delivers competitive performance against modern baselines in audio inpainting and declipping. This work represents the first diffusion-based general framework for solving inverse problems in audio processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.15228v3-abstract-full').style.display = 'none'; document.getElementById('2210.15228v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 27 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accetpted at ICASSP 2023</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.07275">arXiv:2209.07275</a> <span> [<a href="https://arxiv.org/pdf/2209.07275">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1109/IEDM13553.2020.9371901">10.1109/IEDM13553.2020.9371901 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phonon-blocked junction refrigerators for cryogenic quantum devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">E. Mykk盲nen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">J. S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">A. Ronzani</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">A. Kemppinen</a>, <a href="/search/?searchtype=author&query=Alkurdi%2C+A">A. Alkurdi</a>, <a href="/search/?searchtype=author&query=Chapuis%2C+P+-">P. -O. Chapuis</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">M. Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.07275v1-abstract-short" style="display: inline;"> Refrigeration is an important enabler for quantum technology. The very low energy of the fundamental excitations typically utilized in quantum technology devices and systems requires temperature well below 1 K. Expensive cryostats are utilized in reaching sub-1 K regime and solid-state cooling solutions would revolutionize the field. New electronic micro-coolers based on phonon-blocked semiconduct… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07275v1-abstract-full').style.display = 'inline'; document.getElementById('2209.07275v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.07275v1-abstract-full" style="display: none;"> Refrigeration is an important enabler for quantum technology. The very low energy of the fundamental excitations typically utilized in quantum technology devices and systems requires temperature well below 1 K. Expensive cryostats are utilized in reaching sub-1 K regime and solid-state cooling solutions would revolutionize the field. New electronic micro-coolers based on phonon-blocked semiconductor-superconductor junctions could provide a viable route to such miniaturization. Here, we investigate the performance limits of these junction refrigerators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.07275v1-abstract-full').style.display = 'none'; document.getElementById('2209.07275v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures, published in 2020 International Electron Devices Meeting (IEDM)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> IEEE International Electron Devices Meeting (IEDM), 2020, pp. 25.8.1-25.8.4 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.12131">arXiv:2208.12131</a> <span> [<a href="https://arxiv.org/pdf/2208.12131">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s42005-024-01806-3">10.1038/s42005-024-01806-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Scalable on-chip multiplexing of silicon single and double quantum dots </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bohuslavskyi%2C+H">Heorhii Bohuslavskyi</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">Alberto Ronzani</a>, <a href="/search/?searchtype=author&query=H%C3%A4tinen%2C+J">Joel H盲tinen</a>, <a href="/search/?searchtype=author&query=Rantala%2C+A">Arto Rantala</a>, <a href="/search/?searchtype=author&query=Shchepetov%2C+A">Andrey Shchepetov</a>, <a href="/search/?searchtype=author&query=Koppinen%2C+P">Panu Koppinen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.12131v4-abstract-short" style="display: inline;"> Owing to the maturity of complementary metal oxide semiconductor (CMOS) microelectronics, qubits realized with spins in silicon quantum dots (QDs) are considered among the most promising technologies for building scalable quantum computers. For this goal, ultra-low-power on-chip cryogenic CMOS (cryo-CMOS) electronics for control, read-out, and interfacing of the qubits is an important milestone. W… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12131v4-abstract-full').style.display = 'inline'; document.getElementById('2208.12131v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.12131v4-abstract-full" style="display: none;"> Owing to the maturity of complementary metal oxide semiconductor (CMOS) microelectronics, qubits realized with spins in silicon quantum dots (QDs) are considered among the most promising technologies for building scalable quantum computers. For this goal, ultra-low-power on-chip cryogenic CMOS (cryo-CMOS) electronics for control, read-out, and interfacing of the qubits is an important milestone. We report on-chip interfacing of tunable electron and hole QDs by a 64-channel cryo-CMOS multiplexer with less-than-detectable static power dissipation. We analyze charge noise and measure state-of-the-art addition energies and gate lever arm parameters in the QDs. We correlate low noise in QDs and sharp turn-on characteristics in cryogenic transistors, both fabricated with the same gate stack. Finally, we demonstrate that our hybrid quantum-CMOS technology provides a route to scalable interfacing of a large number of QD devices, enabling, for example, variability analysis and QD qubit geometry optimization, which are prerequisites for building large-scale silicon-based quantum computers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12131v4-abstract-full').style.display = 'none'; document.getElementById('2208.12131v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">accepted manuscript; 5 figures, 18 supplementary figures, and 1 table in supplementary materials</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Communications Physics 7, 323 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.01413">arXiv:2207.01413</a> <span> [<a href="https://arxiv.org/pdf/2207.01413">pdf</a>, <a href="https://arxiv.org/format/2207.01413">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> </div> </div> <p class="title is-5 mathjax"> Disentangling Random and Cyclic Effects in Time-Lapse Sequences </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=H%C3%A4rk%C3%B6nen%2C+E">Erik H盲rk枚nen</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Kynk%C3%A4%C3%A4nniemi%2C+T">Tuomas Kynk盲盲nniemi</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.01413v1-abstract-short" style="display: inline;"> Time-lapse image sequences offer visually compelling insights into dynamic processes that are too slow to observe in real time. However, playing a long time-lapse sequence back as a video often results in distracting flicker due to random effects, such as weather, as well as cyclic effects, such as the day-night cycle. We introduce the problem of disentangling time-lapse sequences in a way that al… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.01413v1-abstract-full').style.display = 'inline'; document.getElementById('2207.01413v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.01413v1-abstract-full" style="display: none;"> Time-lapse image sequences offer visually compelling insights into dynamic processes that are too slow to observe in real time. However, playing a long time-lapse sequence back as a video often results in distracting flicker due to random effects, such as weather, as well as cyclic effects, such as the day-night cycle. We introduce the problem of disentangling time-lapse sequences in a way that allows separate, after-the-fact control of overall trends, cyclic effects, and random effects in the images, and describe a technique based on data-driven generative models that achieves this goal. This enables us to "re-render" the sequences in ways that would not be possible with the input images alone. For example, we can stabilize a long sequence to focus on plant growth over many months, under selectable, consistent weather. Our approach is based on Generative Adversarial Networks (GAN) that are conditioned with the time coordinate of the time-lapse sequence. Our architecture and training procedure are designed so that the networks learn to model random variations, such as weather, using the GAN's latent space, and to disentangle overall trends and cyclic variations by feeding the conditioning time label to the model using Fourier features with specific frequencies. We show that our models are robust to defects in the training data, enabling us to amend some of the practical difficulties in capturing long time-lapse sequences, such as temporary occlusions, uneven frame spacing, and missing frames. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.01413v1-abstract-full').style.display = 'none'; document.getElementById('2207.01413v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to SIGGRAPH 2022. Code: https://github.com/harskish/tlgan</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.03429">arXiv:2206.03429</a> <span> [<a href="https://arxiv.org/pdf/2206.03429">pdf</a>, <a href="https://arxiv.org/format/2206.03429">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> </div> </div> <p class="title is-5 mathjax"> Generating Long Videos of Dynamic Scenes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Brooks%2C+T">Tim Brooks</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Wang%2C+T">Ting-Chun Wang</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Liu%2C+M">Ming-Yu Liu</a>, <a href="/search/?searchtype=author&query=Efros%2C+A+A">Alexei A. Efros</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.03429v2-abstract-short" style="display: inline;"> We present a video generation model that accurately reproduces object motion, changes in camera viewpoint, and new content that arises over time. Existing video generation methods often fail to produce new content as a function of time while maintaining consistencies expected in real environments, such as plausible dynamics and object persistence. A common failure case is for content to never chan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03429v2-abstract-full').style.display = 'inline'; document.getElementById('2206.03429v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.03429v2-abstract-full" style="display: none;"> We present a video generation model that accurately reproduces object motion, changes in camera viewpoint, and new content that arises over time. Existing video generation methods often fail to produce new content as a function of time while maintaining consistencies expected in real environments, such as plausible dynamics and object persistence. A common failure case is for content to never change due to over-reliance on inductive biases to provide temporal consistency, such as a single latent code that dictates content for the entire video. On the other extreme, without long-term consistency, generated videos may morph unrealistically between different scenes. To address these limitations, we prioritize the time axis by redesigning the temporal latent representation and learning long-term consistency from data by training on longer videos. To this end, we leverage a two-phase training strategy, where we separately train using longer videos at a low resolution and shorter videos at a high resolution. To evaluate the capabilities of our model, we introduce two new benchmark datasets with explicit focus on long-term temporal dynamics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.03429v2-abstract-full').style.display = 'none'; document.getElementById('2206.03429v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.13398">arXiv:2203.13398</a> <span> [<a href="https://arxiv.org/pdf/2203.13398">pdf</a>, <a href="https://arxiv.org/format/2203.13398">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.21105/astro.2203.13398">10.21105/astro.2203.13398 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> V889 Her: abrupt changes in the magnetic field or differential rotation? </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Willamo%2C+T">Teemu Willamo</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Korpi-Lagg%2C+M">Maarit Korpi-Lagg</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.13398v2-abstract-short" style="display: inline;"> We have applied Zeeman-Doppler imaging (ZDI) to an extensive spectropolarimetric HARPSpol data set of the magnetically active young solar analogue V889 Her, covering 35 spectra obtained during six nights in May 2011. The data set allows us to study Stokes V profiles of the star at almost identical rotational phases, separated by one or more stellar rotations. We use these data to study if the line… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13398v2-abstract-full').style.display = 'inline'; document.getElementById('2203.13398v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.13398v2-abstract-full" style="display: none;"> We have applied Zeeman-Doppler imaging (ZDI) to an extensive spectropolarimetric HARPSpol data set of the magnetically active young solar analogue V889 Her, covering 35 spectra obtained during six nights in May 2011. The data set allows us to study Stokes V profiles of the star at almost identical rotational phases, separated by one or more stellar rotations. We use these data to study if the line profiles evolve from one rotation to the next, and find that some evolution does indeed occur. We consider two possible explanations for this: abrupt changes in the large-scale magnetic field or differential rotation. We find it quite difficult to distinguish between the two alternatives using ZDI alone. A strong differential rotation could, however, explain the changes in the line profiles, so we conclude that it must be present, and the abrupt magnetic field evolution is left uncertain. Commonly, rapidly rotating stars are assumed to have only weak differential rotation. If the strong differential rotation of V889 Her is indeed present, as has been found in other studies as well, it could indicate that the theoretical and numerical results of differential rotation still need to be revised. The rapid changes that may have occurred in the magnetic field indicate that one should be quite cautious when interpreting ZDI maps constructed from data over long time intervals. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.13398v2-abstract-full').style.display = 'none'; document.getElementById('2203.13398v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.06026">arXiv:2203.06026</a> <span> [<a href="https://arxiv.org/pdf/2203.06026">pdf</a>, <a href="https://arxiv.org/format/2203.06026">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> The Role of ImageNet Classes in Fr茅chet Inception Distance </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kynk%C3%A4%C3%A4nniemi%2C+T">Tuomas Kynk盲盲nniemi</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.06026v3-abstract-short" style="display: inline;"> Fr茅chet Inception Distance (FID) is the primary metric for ranking models in data-driven generative modeling. While remarkably successful, the metric is known to sometimes disagree with human judgement. We investigate a root cause of these discrepancies, and visualize what FID "looks at" in generated images. We show that the feature space that FID is (typically) computed in is so close to the Imag… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.06026v3-abstract-full').style.display = 'inline'; document.getElementById('2203.06026v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.06026v3-abstract-full" style="display: none;"> Fr茅chet Inception Distance (FID) is the primary metric for ranking models in data-driven generative modeling. While remarkably successful, the metric is known to sometimes disagree with human judgement. We investigate a root cause of these discrepancies, and visualize what FID "looks at" in generated images. We show that the feature space that FID is (typically) computed in is so close to the ImageNet classifications that aligning the histograms of Top-$N$ classifications between sets of generated and real images can reduce FID substantially -- without actually improving the quality of results. Thus, we conclude that FID is prone to intentional or accidental distortions. As a practical example of an accidental distortion, we discuss a case where an ImageNet pre-trained FastGAN achieves a FID comparable to StyleGAN2, while being worse in terms of human evaluation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.06026v3-abstract-full').style.display = 'none'; document.getElementById('2203.06026v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">ICLR 2023 camera ready. Code: https://github.com/kynkaat/role-of-imagenet-classes-in-fid</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2201.04715">arXiv:2201.04715</a> <span> [<a href="https://arxiv.org/pdf/2201.04715">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1117/1.APN.2.2.024002">10.1117/1.APN.2.2.024002 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Supporting quantum technologies with an ultra-low loss silicon photonics platform </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cherchi%2C+M">Matteo Cherchi</a>, <a href="/search/?searchtype=author&query=Bera%2C+A">Arijit Bera</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">Antti Kemppinen</a>, <a href="/search/?searchtype=author&query=Nissil%C3%A4%2C+J">Jaani Nissil盲</a>, <a href="/search/?searchtype=author&query=Tappura%2C+K">Kirsi Tappura</a>, <a href="/search/?searchtype=author&query=Caputo%2C+M">Marco Caputo</a>, <a href="/search/?searchtype=author&query=Lehtim%C3%A4ki%2C+L">Lauri Lehtim盲ki</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Janne Lehtinen</a>, <a href="/search/?searchtype=author&query=Govenius%2C+J">Joonas Govenius</a>, <a href="/search/?searchtype=author&query=Hassinen%2C+T">Tomi Hassinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Aalto%2C+T">Timo Aalto</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2201.04715v4-abstract-short" style="display: inline;"> Photonic integrated circuits (PICs) are expected to play a significant role in the ongoing second quantum revolution, thanks to their stability and scalability. Still, major upgrades are needed for available PIC platforms to meet the demanding requirements of quantum devices. In this paper, we present a review of our recent progress in upgrading an unconventional silicon photonics platform towards… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.04715v4-abstract-full').style.display = 'inline'; document.getElementById('2201.04715v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2201.04715v4-abstract-full" style="display: none;"> Photonic integrated circuits (PICs) are expected to play a significant role in the ongoing second quantum revolution, thanks to their stability and scalability. Still, major upgrades are needed for available PIC platforms to meet the demanding requirements of quantum devices. In this paper, we present a review of our recent progress in upgrading an unconventional silicon photonics platform towards such goal, including ultra-low propagation losses, low fibre coupling losses, integration of superconducting elements, Faraday rotators, fast and efficient detectors, as well as phase modulators with low loss and/or low energy consumption. We show the relevance of our developments and of our vision in two main applications: quantum key distribution - to achieve significantly higher key rates and large-scale deployment - and cryogenic quantum computers - to replace electrical connections to the cryostat with optical fibres. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2201.04715v4-abstract-full').style.display = 'none'; document.getElementById('2201.04715v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 January, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 14 figures, 159 references</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.06145">arXiv:2111.06145</a> <span> [<a href="https://arxiv.org/pdf/2111.06145">pdf</a>, <a href="https://arxiv.org/format/2111.06145">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> </div> <p class="title is-5 mathjax"> Broadband continuous variable entanglement generation using Kerr-free Josephson metamaterial </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Perelshtein%2C+M">Michael Perelshtein</a>, <a href="/search/?searchtype=author&query=Petrovnin%2C+K">Kirill Petrovnin</a>, <a href="/search/?searchtype=author&query=Vesterinen%2C+V">Visa Vesterinen</a>, <a href="/search/?searchtype=author&query=Raja%2C+S+H">Sina Hamedani Raja</a>, <a href="/search/?searchtype=author&query=Lilja%2C+I">Ilari Lilja</a>, <a href="/search/?searchtype=author&query=Will%2C+M">Marco Will</a>, <a href="/search/?searchtype=author&query=Savin%2C+A">Alexander Savin</a>, <a href="/search/?searchtype=author&query=Simbierowicz%2C+S">Slawomir Simbierowicz</a>, <a href="/search/?searchtype=author&query=Jabdaraghi%2C+R">Robab Jabdaraghi</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Janne Lehtinen</a>, <a href="/search/?searchtype=author&query=Gr%C3%B6nberg%2C+L">Leif Gr枚nberg</a>, <a href="/search/?searchtype=author&query=Hassel%2C+J">Juha Hassel</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Govenius%2C+J">Joonas Govenius</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+S">Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Hakonen%2C+P">Pertti Hakonen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.06145v2-abstract-short" style="display: inline;"> Entangled microwave photons form a fundamental resource for quantum information processing and sensing with continuous variables. We use a low-loss Josephson metamaterial comprising superconducting, non-linear, asymmetric inductive elements to generate frequency-entangled photons from vacuum fluctuations at a rate of 2 giga entangled bits per second spanning over 4 GHz bandwidth. The device is ope… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06145v2-abstract-full').style.display = 'inline'; document.getElementById('2111.06145v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.06145v2-abstract-full" style="display: none;"> Entangled microwave photons form a fundamental resource for quantum information processing and sensing with continuous variables. We use a low-loss Josephson metamaterial comprising superconducting, non-linear, asymmetric inductive elements to generate frequency-entangled photons from vacuum fluctuations at a rate of 2 giga entangled bits per second spanning over 4 GHz bandwidth. The device is operated as a traveling wave parametric amplifier under Kerr-relieving biasing conditions. Furthermore, we realize the first successfully demonstration of single-mode squeezing in such devices -- $3.1\pm0.7$\,dB below the zero-point level at half of modulation frequency. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.06145v2-abstract-full').style.display = 'none'; document.getElementById('2111.06145v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 9 figures including supplement</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2110.06729">arXiv:2110.06729</a> <span> [<a href="https://arxiv.org/pdf/2110.06729">pdf</a>, <a href="https://arxiv.org/format/2110.06729">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202141649">10.1051/0004-6361/202141649 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Zeeman-Doppler imaging of five young solar-type stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Willamo%2C+T">T. Willamo</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">M. J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/?searchtype=author&query=Jeffers%2C+S+V">S. V. Jeffers</a>, <a href="/search/?searchtype=author&query=Korhonen%2C+H">H. Korhonen</a>, <a href="/search/?searchtype=author&query=Marsden%2C+S+C">S. C. Marsden</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2110.06729v2-abstract-short" style="display: inline;"> The magnetic activity of the Sun changes with the solar cycle. Similar cycles are found in other stars as well, but their details are not known to a similar degree. Characterising stellar magnetic cycles is important for the understanding of the stellar and solar dynamos that are driving the magnetic activity. We present spectropolarimetric observations of five young, solar-type stars, and compare… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06729v2-abstract-full').style.display = 'inline'; document.getElementById('2110.06729v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2110.06729v2-abstract-full" style="display: none;"> The magnetic activity of the Sun changes with the solar cycle. Similar cycles are found in other stars as well, but their details are not known to a similar degree. Characterising stellar magnetic cycles is important for the understanding of the stellar and solar dynamos that are driving the magnetic activity. We present spectropolarimetric observations of five young, solar-type stars, and compare them to previous observations, with the aim to identify and characterise stellar equivalents of the solar cycle. We use Zeeman-Doppler imaging (ZDI) to map the surface magnetic field and brightness of our targets. The magnetic field is decomposed into spherical harmonic expansions, from which we report the strengths of the axisymmetric vs. non-axisymmetric, and poloidal vs. toroidal components, and compare them to the Rossby numbers of the stars. We present five new ZDI-maps of young, solar-type stars from Dec 2017. Of special interest is the case of V1358 Ori, that has gone through a polarity reversal between our observations and earlier ones. A less evident polarity reversal might also have occurred in HD 35296. There is a preference for more axisymmetric field, and possibly more toroidal field, for the more active stars with lower Rossby number, but a larger sample should be studied to draw any strong conclusions from this. For most of the individual stars, the amounts of toroidal and poloidal field have stayed on similar levels as in earlier observations. We find evidence for a magnetic polarity reversal having occurred in V1358 Ori. \c{hi}1 Ori could be an interesting target for future observations, with a possible short magnetic cycle of a few years. The correlation between the brightness maps and the magnetic field is mostly poor, which could indicate the presence of small-scale magnetic features of different polarities, that cancel each other out, and are not resolved in our maps. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2110.06729v2-abstract-full').style.display = 'none'; document.getElementById('2110.06729v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 659, A71 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.01567">arXiv:2107.01567</a> <span> [<a href="https://arxiv.org/pdf/2107.01567">pdf</a>, <a href="https://arxiv.org/format/2107.01567">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s42005-021-00648-7">10.1038/s42005-021-00648-7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Superconducting insulators and localization of Cooper pairs </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Arutyunov%2C+K+Y">Konstantin Yu. Arutyunov</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Radkevich%2C+A">Alexey Radkevich</a>, <a href="/search/?searchtype=author&query=Semenov%2C+A+G">Andrew G. Semenov</a>, <a href="/search/?searchtype=author&query=Zaikin%2C+A+D">Andrei D. Zaikin</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2107.01567v1-abstract-short" style="display: inline;"> Rapid miniaturization of electronic devices and circuits demands profound understanding of fluctuation phenomena at the nanoscale. Superconducting nanowires -- serving as important building blocks for such devices -- may seriously suffer from fluctuations which tend to destroy long-range order and suppress superconductivity. In particular, quantum phase slips (QPS) proliferating at low temperature… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.01567v1-abstract-full').style.display = 'inline'; document.getElementById('2107.01567v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.01567v1-abstract-full" style="display: none;"> Rapid miniaturization of electronic devices and circuits demands profound understanding of fluctuation phenomena at the nanoscale. Superconducting nanowires -- serving as important building blocks for such devices -- may seriously suffer from fluctuations which tend to destroy long-range order and suppress superconductivity. In particular, quantum phase slips (QPS) proliferating at low temperatures may turn a quasi-one-dimensional superconductor into a resistor or an insulator. Here, we introduce a physical concept of QPS-controlled localization of Cooper pairs that may occur even in uniform nanowires without any dielectric barriers being a fundamental manifestation of the flux-charge duality in superconductors. We demonstrate -- both experimentally and theoretically -- that deep in the "insulating" state such nanowires actually exhibit non-trivial superposition of superconductivity and weak Coulomb blockade of Cooper pairs generated by quantum tunneling of magnetic fluxons across the wire. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.01567v1-abstract-full').style.display = 'none'; document.getElementById('2107.01567v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 July, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">7+2 pages,5+2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Communications Physics 4, 146 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.12423">arXiv:2106.12423</a> <span> [<a href="https://arxiv.org/pdf/2106.12423">pdf</a>, <a href="https://arxiv.org/format/2106.12423">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Alias-Free Generative Adversarial Networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=H%C3%A4rk%C3%B6nen%2C+E">Erik H盲rk枚nen</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.12423v4-abstract-short" style="display: inline;"> We observe that despite their hierarchical convolutional nature, the synthesis process of typical generative adversarial networks depends on absolute pixel coordinates in an unhealthy manner. This manifests itself as, e.g., detail appearing to be glued to image coordinates instead of the surfaces of depicted objects. We trace the root cause to careless signal processing that causes aliasing in the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.12423v4-abstract-full').style.display = 'inline'; document.getElementById('2106.12423v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.12423v4-abstract-full" style="display: none;"> We observe that despite their hierarchical convolutional nature, the synthesis process of typical generative adversarial networks depends on absolute pixel coordinates in an unhealthy manner. This manifests itself as, e.g., detail appearing to be glued to image coordinates instead of the surfaces of depicted objects. We trace the root cause to careless signal processing that causes aliasing in the generator network. Interpreting all signals in the network as continuous, we derive generally applicable, small architectural changes that guarantee that unwanted information cannot leak into the hierarchical synthesis process. The resulting networks match the FID of StyleGAN2 but differ dramatically in their internal representations, and they are fully equivariant to translation and rotation even at subpixel scales. Our results pave the way for generative models better suited for video and animation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.12423v4-abstract-full').style.display = 'none'; document.getElementById('2106.12423v4-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 October, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2104.03989">arXiv:2104.03989</a> <span> [<a href="https://arxiv.org/pdf/2104.03989">pdf</a>, <a href="https://arxiv.org/format/2104.03989">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> </div> </div> <p class="title is-5 mathjax"> Appearance-Driven Automatic 3D Model Simplification </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Hasselgren%2C+J">Jon Hasselgren</a>, <a href="/search/?searchtype=author&query=Munkberg%2C+J">Jacob Munkberg</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2104.03989v1-abstract-short" style="display: inline;"> We present a suite of techniques for jointly optimizing triangle meshes and shading models to match the appearance of reference scenes. This capability has a number of uses, including appearance-preserving simplification of extremely complex assets, conversion between rendering systems, and even conversion between geometric scene representations. We follow and extend the classic analysis-by-synt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.03989v1-abstract-full').style.display = 'inline'; document.getElementById('2104.03989v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2104.03989v1-abstract-full" style="display: none;"> We present a suite of techniques for jointly optimizing triangle meshes and shading models to match the appearance of reference scenes. This capability has a number of uses, including appearance-preserving simplification of extremely complex assets, conversion between rendering systems, and even conversion between geometric scene representations. We follow and extend the classic analysis-by-synthesis family of techniques: enabled by a highly efficient differentiable renderer and modern nonlinear optimization algorithms, our results are driven to minimize the image-space difference to the target scene when rendered in similar viewing and lighting conditions. As the only signals driving the optimization are differences in rendered images, the approach is highly general and versatile: it easily supports many different forward rendering models such as normal mapping, spatially-varying BRDFs, displacement mapping, etc. Supervision through images only is also key to the ability to easily convert between rendering systems and scene representations. We output triangle meshes with textured materials to ensure that the models render efficiently on modern graphics hardware and benefit from, e.g., hardware-accelerated rasterization, ray tracing, and filtered texture lookups. Our system is integrated in a small Python code base, and can be applied at high resolutions and on large models. We describe several use cases, including mesh decimation, level of detail generation, seamless mesh filtering and approximations of aggregate geometry. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2104.03989v1-abstract-full').style.display = 'none'; document.getElementById('2104.03989v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 April, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">ACM Class:</span> I.3.7 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.03932">arXiv:2101.03932</a> <span> [<a href="https://arxiv.org/pdf/2101.03932">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1109/CPEM49742.2020.9191726">10.1109/CPEM49742.2020.9191726 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coulomb Blockade Thermometry on a Wide Temperature Range </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Hahtela%2C+O+M">O. M. Hahtela</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">A. Kemppinen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Manninen%2C+A+J">A. J. Manninen</a>, <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">E. Mykk盲nen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">M. Prunnila</a>, <a href="/search/?searchtype=author&query=Yurttag%C3%BCl%2C+N">N. Yurttag眉l</a>, <a href="/search/?searchtype=author&query=Blanchet%2C+F">F. Blanchet</a>, <a href="/search/?searchtype=author&query=Gramich%2C+M">M. Gramich</a>, <a href="/search/?searchtype=author&query=Karimi%2C+B">B. Karimi</a>, <a href="/search/?searchtype=author&query=Mannila%2C+E+T">E. T. Mannila</a>, <a href="/search/?searchtype=author&query=Muhojoki%2C+J">J. Muhojoki</a>, <a href="/search/?searchtype=author&query=Peltonen%2C+J+T">J. T. Peltonen</a>, <a href="/search/?searchtype=author&query=Pekola%2C+J+P">J. P. Pekola</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.03932v1-abstract-short" style="display: inline;"> The Coulomb Blockade Thermometer (CBT) is a primary thermometer for cryogenic temperatures, with demonstrated operation from below 1 mK up to 60 K. Its performance as a primary thermometer has been verified at temperatures from 20 mK to 200 mK at uncertainty level below 1 % (k = 2). In a new project, our aim is to extend the metrologically verified temperature range of the primary CBT up to 25 K.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03932v1-abstract-full').style.display = 'inline'; document.getElementById('2101.03932v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.03932v1-abstract-full" style="display: none;"> The Coulomb Blockade Thermometer (CBT) is a primary thermometer for cryogenic temperatures, with demonstrated operation from below 1 mK up to 60 K. Its performance as a primary thermometer has been verified at temperatures from 20 mK to 200 mK at uncertainty level below 1 % (k = 2). In a new project, our aim is to extend the metrologically verified temperature range of the primary CBT up to 25 K. We also demonstrate close-to-ideal operation of a CBT with only two tunnel junctions when the device is embedded in a low-impedance environment. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.03932v1-abstract-full').style.display = 'none'; document.getElementById('2101.03932v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">2 pages, 3 figures, 2020 Conference on Precision Electromagnetic Measurements (CPEM), Denver (Aurora), CO, USA, 2020</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2011.03277">arXiv:2011.03277</a> <span> [<a href="https://arxiv.org/pdf/2011.03277">pdf</a>, <a href="https://arxiv.org/format/2011.03277">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> </div> </div> <p class="title is-5 mathjax"> Modular Primitives for High-Performance Differentiable Rendering </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Seol%2C+Y">Yeongho Seol</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2011.03277v1-abstract-short" style="display: inline;"> We present a modular differentiable renderer design that yields performance superior to previous methods by leveraging existing, highly optimized hardware graphics pipelines. Our design supports all crucial operations in a modern graphics pipeline: rasterizing large numbers of triangles, attribute interpolation, filtered texture lookups, as well as user-programmable shading and geometry processing… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.03277v1-abstract-full').style.display = 'inline'; document.getElementById('2011.03277v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2011.03277v1-abstract-full" style="display: none;"> We present a modular differentiable renderer design that yields performance superior to previous methods by leveraging existing, highly optimized hardware graphics pipelines. Our design supports all crucial operations in a modern graphics pipeline: rasterizing large numbers of triangles, attribute interpolation, filtered texture lookups, as well as user-programmable shading and geometry processing, all in high resolutions. Our modular primitives allow custom, high-performance graphics pipelines to be built directly within automatic differentiation frameworks such as PyTorch or TensorFlow. As a motivating application, we formulate facial performance capture as an inverse rendering problem and show that it can be solved efficiently using our tools. Our results indicate that this simple and straightforward approach achieves excellent geometric correspondence between rendered results and reference imagery. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2011.03277v1-abstract-full').style.display = 'none'; document.getElementById('2011.03277v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.14166">arXiv:2009.14166</a> <span> [<a href="https://arxiv.org/pdf/2009.14166">pdf</a>, <a href="https://arxiv.org/format/2009.14166">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0060652">10.1063/5.0060652 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cascaded superconducting junction refrigerators: optimization and performance limits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kemppinen%2C+A">A. Kemppinen</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">A. Ronzani</a>, <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">E. Mykk盲nen</a>, <a href="/search/?searchtype=author&query=H%C3%A4tinen%2C+J">J. H盲tinen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">J. S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">M. Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.14166v3-abstract-short" style="display: inline;"> We demonstrate highly transparent silicon-vanadium and silicon-aluminum tunnel junctions with relatively low sub-gap leakage current and discuss how a trade-off typically encountered between transparency and leakage affects their refrigeration performance. We theoretically investigate cascaded superconducting tunnel junction refrigerators with two or more refrigeration stages. In particular, we de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.14166v3-abstract-full').style.display = 'inline'; document.getElementById('2009.14166v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.14166v3-abstract-full" style="display: none;"> We demonstrate highly transparent silicon-vanadium and silicon-aluminum tunnel junctions with relatively low sub-gap leakage current and discuss how a trade-off typically encountered between transparency and leakage affects their refrigeration performance. We theoretically investigate cascaded superconducting tunnel junction refrigerators with two or more refrigeration stages. In particular, we develop an approximate method that takes into account self-heating effects but still allows us to optimize the cascade a single stage at a time. We design a cascade consisting of energy-efficient refrigeration stages, which makes cooling of, e.g., quantum devices from above 1 K to below 100 mK a realistic experimental target. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.14166v3-abstract-full').style.display = 'none'; document.getElementById('2009.14166v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 119, 052603 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.13944">arXiv:2009.13944</a> <span> [<a href="https://arxiv.org/pdf/2009.13944">pdf</a>, <a href="https://arxiv.org/format/2009.13944">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1063/5.0040259">10.1063/5.0040259 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Dispersive readout of reconfigurable ambipolar quantum dots in a silicon-on-insulator nanowire </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Duan%2C+J">Jingyu Duan</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Fogarty%2C+M+A">Michael A. Fogarty</a>, <a href="/search/?searchtype=author&query=Schaal%2C+S">Simon Schaal</a>, <a href="/search/?searchtype=author&query=Lam%2C+M">Michelle Lam</a>, <a href="/search/?searchtype=author&query=Ronzani%2C+A">Alberto Ronzani</a>, <a href="/search/?searchtype=author&query=Shchepetov%2C+A">Andrey Shchepetov</a>, <a href="/search/?searchtype=author&query=Koppinen%2C+P">Panu Koppinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Gonzalez-Zalba%2C+F">Fernando Gonzalez-Zalba</a>, <a href="/search/?searchtype=author&query=Morton%2C+J+J+L">John J. L. Morton</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.13944v1-abstract-short" style="display: inline;"> We report on ambipolar gate-defined quantum dots in silicon on insulator (SOI) nanowires fabricated using a customised complementary metal-oxide-semiconductor (CMOS) process. The ambipolarity was achieved by extending a gate over an intrinsic silicon channel to both highly doped n-type and p-type terminals. We utilise the ability to supply ambipolar carrier reservoirs to the silicon channel to dem… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.13944v1-abstract-full').style.display = 'inline'; document.getElementById('2009.13944v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.13944v1-abstract-full" style="display: none;"> We report on ambipolar gate-defined quantum dots in silicon on insulator (SOI) nanowires fabricated using a customised complementary metal-oxide-semiconductor (CMOS) process. The ambipolarity was achieved by extending a gate over an intrinsic silicon channel to both highly doped n-type and p-type terminals. We utilise the ability to supply ambipolar carrier reservoirs to the silicon channel to demonstrate an ability to reconfigurably define, with the same electrodes, double quantum dots with either holes or electrons. We use gate-based reflectometry to sense the inter-dot charge transition(IDT) of both electron and hole double quantum dots, achieving a minimum integration time of 160(100) $渭$s for electrons (holes). Our results present the opportunity to combine, in a single device, the long coherence times of electron spins with the electrically controllable holes spins in silicon. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.13944v1-abstract-full').style.display = 'none'; document.getElementById('2009.13944v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.00040">arXiv:2007.00040</a> <span> [<a href="https://arxiv.org/pdf/2007.00040">pdf</a>, <a href="https://arxiv.org/format/2007.00040">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3847/1538-4357/abe621">10.3847/1538-4357/abe621 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Knee-Point in the Rotation-Activity Scaling of Late-type Stars with a Connection to Dynamo Transitions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">Maarit J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Olspert%2C+N">Nigul Olspert</a>, <a href="/search/?searchtype=author&query=Spada%2C+F">Federico Spada</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.00040v2-abstract-short" style="display: inline;"> The magnetic activity of late-type stars is correlated with their rotation rates. Up to a certain limit, stars with smaller Rossby numbers, defined as the rotation period divided by the convective turnover time, have higher activity. A more detailed look at this rotation-activity relation reveals that, rather than being a simple power law relation, the activity scaling has a shallower slope for th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.00040v2-abstract-full').style.display = 'inline'; document.getElementById('2007.00040v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.00040v2-abstract-full" style="display: none;"> The magnetic activity of late-type stars is correlated with their rotation rates. Up to a certain limit, stars with smaller Rossby numbers, defined as the rotation period divided by the convective turnover time, have higher activity. A more detailed look at this rotation-activity relation reveals that, rather than being a simple power law relation, the activity scaling has a shallower slope for the low-Rossby stars than for the high-Rossby ones. We find that, for the chromospheric CaII H&K activity, this scaling relation is well modelled by a broken two-piece power law. Furthermore, the knee-point of the relation coincides with the axisymmetry to non-axisymmetry transition seen in both the spot activity and surface magnetic field configuration of active stars. We interpret this knee-point as a dynamo transition between dominating axi- and non-axisymmetric dynamo regimes with a different dependence on rotation and discuss this hypothesis in the light of current numerical dynamo models. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.00040v2-abstract-full').style.display = 'none'; document.getElementById('2007.00040v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">10 pages, 5 figures, 2 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Report number:</span> NORDITA-2020-052 </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ApJ 910 110 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.06676">arXiv:2006.06676</a> <span> [<a href="https://arxiv.org/pdf/2006.06676">pdf</a>, <a href="https://arxiv.org/format/2006.06676">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Training Generative Adversarial Networks with Limited Data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.06676v2-abstract-short" style="display: inline;"> Training generative adversarial networks (GAN) using too little data typically leads to discriminator overfitting, causing training to diverge. We propose an adaptive discriminator augmentation mechanism that significantly stabilizes training in limited data regimes. The approach does not require changes to loss functions or network architectures, and is applicable both when training from scratch… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.06676v2-abstract-full').style.display = 'inline'; document.getElementById('2006.06676v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.06676v2-abstract-full" style="display: none;"> Training generative adversarial networks (GAN) using too little data typically leads to discriminator overfitting, causing training to diverge. We propose an adaptive discriminator augmentation mechanism that significantly stabilizes training in limited data regimes. The approach does not require changes to loss functions or network architectures, and is applicable both when training from scratch and when fine-tuning an existing GAN on another dataset. We demonstrate, on several datasets, that good results are now possible using only a few thousand training images, often matching StyleGAN2 results with an order of magnitude fewer images. We expect this to open up new application domains for GANs. We also find that the widely used CIFAR-10 is, in fact, a limited data benchmark, and improve the record FID from 5.59 to 2.42. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.06676v2-abstract-full').style.display = 'none'; document.getElementById('2006.06676v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2004.02546">arXiv:2004.02546</a> <span> [<a href="https://arxiv.org/pdf/2004.02546">pdf</a>, <a href="https://arxiv.org/format/2004.02546">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> </div> </div> <p class="title is-5 mathjax"> GANSpace: Discovering Interpretable GAN Controls </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=H%C3%A4rk%C3%B6nen%2C+E">Erik H盲rk枚nen</a>, <a href="/search/?searchtype=author&query=Hertzmann%2C+A">Aaron Hertzmann</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Paris%2C+S">Sylvain Paris</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2004.02546v3-abstract-short" style="display: inline;"> This paper describes a simple technique to analyze Generative Adversarial Networks (GANs) and create interpretable controls for image synthesis, such as change of viewpoint, aging, lighting, and time of day. We identify important latent directions based on Principal Components Analysis (PCA) applied either in latent space or feature space. Then, we show that a large number of interpretable control… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.02546v3-abstract-full').style.display = 'inline'; document.getElementById('2004.02546v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2004.02546v3-abstract-full" style="display: none;"> This paper describes a simple technique to analyze Generative Adversarial Networks (GANs) and create interpretable controls for image synthesis, such as change of viewpoint, aging, lighting, and time of day. We identify important latent directions based on Principal Components Analysis (PCA) applied either in latent space or feature space. Then, we show that a large number of interpretable controls can be defined by layer-wise perturbation along the principal directions. Moreover, we show that BigGAN can be controlled with layer-wise inputs in a StyleGAN-like manner. We show results on different GANs trained on various datasets, and demonstrate good qualitative matches to edit directions found through earlier supervised approaches. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.02546v3-abstract-full').style.display = 'none'; document.getElementById('2004.02546v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to NeurIPS 2020</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Advances in Neural Information Processing Systems 33 (NeurIPS 2020), 9841-9850 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.08997">arXiv:2003.08997</a> <span> [<a href="https://arxiv.org/pdf/2003.08997">pdf</a>, <a href="https://arxiv.org/format/2003.08997">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41550-020-1039-x">10.1038/s41550-020-1039-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Common dynamo scaling in slowly rotating young and evolved stars </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Spada%2C+F">Federico Spada</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">Maarit J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Olspert%2C+N">Nigul Olspert</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+P+J">Petri J. K盲pyl盲</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2003.08997v1-abstract-short" style="display: inline;"> One interpretation of the activity and magnetism of late-type stars is that these both intensify with decreasing Rossby number up to a saturation level, suggesting that stellar dynamos depend on both rotation and convective turbulence. Some studies have claimed, however, that rotation alone suffices to parametrise this scaling adequately. Here, we tackle the question of the relevance of turbulence… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.08997v1-abstract-full').style.display = 'inline'; document.getElementById('2003.08997v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.08997v1-abstract-full" style="display: none;"> One interpretation of the activity and magnetism of late-type stars is that these both intensify with decreasing Rossby number up to a saturation level, suggesting that stellar dynamos depend on both rotation and convective turbulence. Some studies have claimed, however, that rotation alone suffices to parametrise this scaling adequately. Here, we tackle the question of the relevance of turbulence to stellar dynamos by including evolved, post main sequence stars in the analysis of the rotation-activity relation. These stars rotate very slowly compared with main sequence stars, but exhibit similar activity levels. We show that the two evolutionary stages fall together in the rotation-activity diagram and form a single sequence in the unsaturated regime in relation only to Rossby numbers derived from stellar models, confirming earlier preliminary results that relied on a more simplistic parametrisation of the convective turnover time. This mirrors recent results of fully convective M dwarfs, which likewise fall on the same rotation-activity sequence as partially convective solar-type stars. Our results demonstrate that turbulence plays a crucial role in driving stellar dynamos and suggest that there is a common turbulence-related dynamo mechanism explaining the magnetic activity of all late-type stars. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.08997v1-abstract-full').style.display = 'none'; document.getElementById('2003.08997v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This is the initial submission version of the paper "Common dynamo scaling in slowly rotating young and evolved stars" (Lehtinen et al. 2020). The final version accepted in Nature Astronomy can be found at https://www.nature.com/articles/s41550-020-1039-x</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.10469">arXiv:2002.10469</a> <span> [<a href="https://arxiv.org/pdf/2002.10469">pdf</a>, <a href="https://arxiv.org/format/2002.10469">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201937185">10.1051/0004-6361/201937185 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hidden magnetic fields of young suns </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Wehrhahn%2C+A">A. Wehrhahn</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.10469v1-abstract-short" style="display: inline;"> Global magnetic fields of active solar-like stars are nowadays routinely detected with spectropolarimetric measurements and are mapped with Zeeman-Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry captures only a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a small-scale compone… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.10469v1-abstract-full').style.display = 'inline'; document.getElementById('2002.10469v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.10469v1-abstract-full" style="display: none;"> Global magnetic fields of active solar-like stars are nowadays routinely detected with spectropolarimetric measurements and are mapped with Zeeman-Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry captures only a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a small-scale component. Analysis of Zeeman broadening in high-resolution intensity spectra can reveal these hidden complex magnetic fields. Historically, there were very few attempts to obtain such measurements for G dwarf stars due to the difficulty of disentangling Zeeman effect from other broadening mechanisms affecting spectral lines. Here we developed a new magnetic field diagnostic method based on relative Zeeman intensification of optical atomic lines with different magnetic sensitivity. Using this technique we obtained 78 field strength measurements for 15 Sun-like stars, including some of the best-studied young solar twins. We find that the average magnetic field strength $Bf$ drops from 1.3-2.0 kG in stars younger than about 120 Myr to 0.2-0.8 kG in older stars. The mean field strength shows a clear correlation with the Rossby number and with the coronal and chromospheric emission indicators. Our results suggest that magnetic regions have roughly the same local field strength $B\approx3.2$ kG in all stars, with the filling factor $f$ of these regions systematically increasing with stellar activity. Comparing our results with the spectropolarimetric analyses of global magnetic fields in the same stars, we find that ZDI recovers about 1% of the total magnetic field energy in the most active stars. This figure drops to just 0.01% for the least active targets. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.10469v1-abstract-full').style.display = 'none'; document.getElementById('2002.10469v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">25 pages, 26 figures; accepted for publication in A&A</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 635, A142 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2002.04300">arXiv:2002.04300</a> <span> [<a href="https://arxiv.org/pdf/2002.04300">pdf</a>, <a href="https://arxiv.org/format/2002.04300">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/202037666">10.1051/0004-6361/202037666 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Shapes of stellar activity cycles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Willamo%2C+T">T. Willamo</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">M. J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Olspert%2C+N">N. Olspert</a>, <a href="/search/?searchtype=author&query=Viviani%2C+M">M. Viviani</a>, <a href="/search/?searchtype=author&query=Warnecke%2C+J">J. Warnecke</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2002.04300v2-abstract-short" style="display: inline;"> Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in other stars. Our aim is to study whether the asymmetric shape of the solar cycle is common in other stars as well, and compare the cycle asymmetry to other ste… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.04300v2-abstract-full').style.display = 'inline'; document.getElementById('2002.04300v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2002.04300v2-abstract-full" style="display: none;"> Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in other stars. Our aim is to study whether the asymmetric shape of the solar cycle is common in other stars as well, and compare the cycle asymmetry to other stellar parameters. We also study the differences in the shape of the solar cycle, depending on what activity indicator is used. The observations are also compared to simulated activity cycles. We use the chromospheric Ca II H&K data from the Mount Wilson Observatory HK Project. From this data set we identify 47 individual cycles from 18 stars. We use the statistical skewness of a cycle as a measure of its asymmetry, and compare this to other stellar parameters. A similar analysis has been done to magnetic cycles extracted from direct numerical magnetohydrodynamic simulations of solar-type convection zones. The shape of the solar cycle (fast rise and slower decline) is common in other stars as well, although the Sun has particularly asymmetric cycles. Cycle-to-cycle variations are large, but the average shape of a cycle is still fairly well represented by a sinusoid. We find only slight correlations between the cycle asymmetry and other stellar parameters. There are large differences in the shape of the solar cycle, depending on what activity indicator is used. In the simulated cycles, there is a difference in the symmetry of global simulations covering the full longitudinal range, hence capable of exciting non-axisymmetric dynamo modes, versus wedge simulations covering a partial extent in longitude, where only axisymmetric modes are possible. The former produce preferentially positive skewness, while the latter a negative one. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2002.04300v2-abstract-full').style.display = 'none'; document.getElementById('2002.04300v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 April, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 February, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to A&A; 12 pages, 12 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 638, A69 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.04958">arXiv:1912.04958</a> <span> [<a href="https://arxiv.org/pdf/1912.04958">pdf</a>, <a href="https://arxiv.org/format/1912.04958">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Image and Video Processing">eess.IV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Analyzing and Improving the Image Quality of StyleGAN </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Hellsten%2C+J">Janne Hellsten</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1912.04958v2-abstract-short" style="display: inline;"> The style-based GAN architecture (StyleGAN) yields state-of-the-art results in data-driven unconditional generative image modeling. We expose and analyze several of its characteristic artifacts, and propose changes in both model architecture and training methods to address them. In particular, we redesign the generator normalization, revisit progressive growing, and regularize the generator to enc… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.04958v2-abstract-full').style.display = 'inline'; document.getElementById('1912.04958v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.04958v2-abstract-full" style="display: none;"> The style-based GAN architecture (StyleGAN) yields state-of-the-art results in data-driven unconditional generative image modeling. We expose and analyze several of its characteristic artifacts, and propose changes in both model architecture and training methods to address them. In particular, we redesign the generator normalization, revisit progressive growing, and regularize the generator to encourage good conditioning in the mapping from latent codes to images. In addition to improving image quality, this path length regularizer yields the additional benefit that the generator becomes significantly easier to invert. This makes it possible to reliably attribute a generated image to a particular network. We furthermore visualize how well the generator utilizes its output resolution, and identify a capacity problem, motivating us to train larger models for additional quality improvements. Overall, our improved model redefines the state of the art in unconditional image modeling, both in terms of existing distribution quality metrics as well as perceived image quality. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.04958v2-abstract-full').style.display = 'none'; document.getElementById('1912.04958v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2019. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1909.11028">arXiv:1909.11028</a> <span> [<a href="https://arxiv.org/pdf/1909.11028">pdf</a>, <a href="https://arxiv.org/ps/1909.11028">ps</a>, <a href="https://arxiv.org/format/1909.11028">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201936780">10.1051/0004-6361/201936780 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Topological changes in the magnetic field of LQ Hya during an activity minimum </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">Maarit J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/?searchtype=author&query=Willamo%2C+T">Teemu Willamo</a>, <a href="/search/?searchtype=author&query=Marsden%2C+S+C">Stephen C. Marsden</a>, <a href="/search/?searchtype=author&query=Jeffers%2C+S+V">Sandra V. Jeffers</a>, <a href="/search/?searchtype=author&query=Henry%2C+G+W">Gregory W. Henry</a>, <a href="/search/?searchtype=author&query=Jetsu%2C+L">Lauri Jetsu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1909.11028v2-abstract-short" style="display: inline;"> Previous studies have related surface temperature maps, obtained with the Doppler imaging (DI) technique, of LQ Hya with long-term photometry. We compare surface magnetic field maps, obtained with the Zeeman Doppler imaging (ZDI) technique, with contemporaneous photometry, with the aim of quantifying the star's magnetic cycle characteristics. We inverted Stokes IV spectropolarimetry into magnetic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.11028v2-abstract-full').style.display = 'inline'; document.getElementById('1909.11028v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1909.11028v2-abstract-full" style="display: none;"> Previous studies have related surface temperature maps, obtained with the Doppler imaging (DI) technique, of LQ Hya with long-term photometry. We compare surface magnetic field maps, obtained with the Zeeman Doppler imaging (ZDI) technique, with contemporaneous photometry, with the aim of quantifying the star's magnetic cycle characteristics. We inverted Stokes IV spectropolarimetry into magnetic field and surface brightness maps using a tomographic inversion code that models high signal-to-noise ratio mean line profiles produced by the least squares deconvolution (LSD) technique. The magnetic field and surface brightness maps reveal similar patterns to previous DI and ZDI studies: non-axisymmetric polar magnetic field structure, void of fields at mid-latitudes, and a complex structure in the equatorial regions. There is a weak but clear tendency of the polar structures to be linked with strong radial field and the equatorial ones with the azimuthal. We find a polarity reversal in the radial field between 2016 and 2017 coincident with an activity minimum seen in the long-term photometry. The inverted field strengths cannot easily be related with the observed spottedness, but we find that they are partially connected with the retrieved field complexity. Comparing to global magnetoconvection models for rapidly rotating young Suns, this field topology and dominance of the poloidal field component could be explained by a turbulent dynamo, where differential rotation does not play a major role (so called alpha^2 Omega or alpha^2 dynamos), and axi- and non-axisymmetric modes are excited simultaneously. The complex equatorial magnetic field structure could arise from the twisted (helical) wreaths often seen in these simulations, while the polar feature would be connected to the mostly poloidal non-axisymmetric component having a smooth spatial structure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1909.11028v2-abstract-full').style.display = 'none'; document.getElementById('1909.11028v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">13 pages, 8 figures, 7 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 660, A141 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.01210">arXiv:1908.01210</a> <span> [<a href="https://arxiv.org/pdf/1908.01210">pdf</a>, <a href="https://arxiv.org/format/1908.01210">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> </div> </div> <p class="title is-5 mathjax"> Learning to Predict 3D Objects with an Interpolation-based Differentiable Renderer </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Chen%2C+W">Wenzheng Chen</a>, <a href="/search/?searchtype=author&query=Gao%2C+J">Jun Gao</a>, <a href="/search/?searchtype=author&query=Ling%2C+H">Huan Ling</a>, <a href="/search/?searchtype=author&query=Smith%2C+E+J">Edward J. Smith</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Jacobson%2C+A">Alec Jacobson</a>, <a href="/search/?searchtype=author&query=Fidler%2C+S">Sanja Fidler</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1908.01210v2-abstract-short" style="display: inline;"> Many machine learning models operate on images, but ignore the fact that images are 2D projections formed by 3D geometry interacting with light, in a process called rendering. Enabling ML models to understand image formation might be key for generalization. However, due to an essential rasterization step involving discrete assignment operations, rendering pipelines are non-differentiable and thus… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.01210v2-abstract-full').style.display = 'inline'; document.getElementById('1908.01210v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.01210v2-abstract-full" style="display: none;"> Many machine learning models operate on images, but ignore the fact that images are 2D projections formed by 3D geometry interacting with light, in a process called rendering. Enabling ML models to understand image formation might be key for generalization. However, due to an essential rasterization step involving discrete assignment operations, rendering pipelines are non-differentiable and thus largely inaccessible to gradient-based ML techniques. In this paper, we present {\emph DIB-R}, a differentiable rendering framework which allows gradients to be analytically computed for all pixels in an image. Key to our approach is to view foreground rasterization as a weighted interpolation of local properties and background rasterization as a distance-based aggregation of global geometry. Our approach allows for accurate optimization over vertex positions, colors, normals, light directions and texture coordinates through a variety of lighting models. We showcase our approach in two ML applications: single-image 3D object prediction, and 3D textured object generation, both trained using exclusively using 2D supervision. Our project website is: https://nv-tlabs.github.io/DIB-R/ <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.01210v2-abstract-full').style.display = 'none'; document.getElementById('1908.01210v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 August, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted to NeurIPS 2019</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1906.03973">arXiv:1906.03973</a> <span> [<a href="https://arxiv.org/pdf/1906.03973">pdf</a>, <a href="https://arxiv.org/format/1906.03973">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> </div> </div> <p class="title is-5 mathjax"> E-LPIPS: Robust Perceptual Image Similarity via Random Transformation Ensembles </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kettunen%2C+M">Markus Kettunen</a>, <a href="/search/?searchtype=author&query=H%C3%A4rk%C3%B6nen%2C+E">Erik H盲rk枚nen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1906.03973v2-abstract-short" style="display: inline;"> It has been recently shown that the hidden variables of convolutional neural networks make for an efficient perceptual similarity metric that accurately predicts human judgment on relative image similarity assessment. First, we show that such learned perceptual similarity metrics (LPIPS) are susceptible to adversarial attacks that dramatically contradict human visual similarity judgment. While thi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1906.03973v2-abstract-full').style.display = 'inline'; document.getElementById('1906.03973v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1906.03973v2-abstract-full" style="display: none;"> It has been recently shown that the hidden variables of convolutional neural networks make for an efficient perceptual similarity metric that accurately predicts human judgment on relative image similarity assessment. First, we show that such learned perceptual similarity metrics (LPIPS) are susceptible to adversarial attacks that dramatically contradict human visual similarity judgment. While this is not surprising in light of neural networks' well-known weakness to adversarial perturbations, we proceed to show that self-ensembling with an infinite family of random transformations of the input --- a technique known not to render classification networks robust --- is enough to turn the metric robust against attack, while retaining predictive power on human judgments. Finally, we study the geometry imposed by our our novel self-ensembled metric (E-LPIPS) on the space of natural images. We find evidence of "perceptual convexity" by showing that convex combinations of similar-looking images retain appearance, and that discrete geodesics yield meaningful frame interpolation and texture morphing, all without explicit correspondences. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1906.03973v2-abstract-full').style.display = 'none'; document.getElementById('1906.03973v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Code and supplemental material available at https://github.com/mkettune/elpips/</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.01723">arXiv:1905.01723</a> <span> [<a href="https://arxiv.org/pdf/1905.01723">pdf</a>, <a href="https://arxiv.org/format/1905.01723">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Artificial Intelligence">cs.AI</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Graphics">cs.GR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Multimedia">cs.MM</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Few-Shot Unsupervised Image-to-Image Translation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Liu%2C+M">Ming-Yu Liu</a>, <a href="/search/?searchtype=author&query=Huang%2C+X">Xun Huang</a>, <a href="/search/?searchtype=author&query=Mallya%2C+A">Arun Mallya</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Kautz%2C+J">Jan Kautz</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1905.01723v2-abstract-short" style="display: inline;"> Unsupervised image-to-image translation methods learn to map images in a given class to an analogous image in a different class, drawing on unstructured (non-registered) datasets of images. While remarkably successful, current methods require access to many images in both source and destination classes at training time. We argue this greatly limits their use. Drawing inspiration from the human cap… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.01723v2-abstract-full').style.display = 'inline'; document.getElementById('1905.01723v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.01723v2-abstract-full" style="display: none;"> Unsupervised image-to-image translation methods learn to map images in a given class to an analogous image in a different class, drawing on unstructured (non-registered) datasets of images. While remarkably successful, current methods require access to many images in both source and destination classes at training time. We argue this greatly limits their use. Drawing inspiration from the human capability of picking up the essence of a novel object from a small number of examples and generalizing from there, we seek a few-shot, unsupervised image-to-image translation algorithm that works on previously unseen target classes that are specified, at test time, only by a few example images. Our model achieves this few-shot generation capability by coupling an adversarial training scheme with a novel network design. Through extensive experimental validation and comparisons to several baseline methods on benchmark datasets, we verify the effectiveness of the proposed framework. Our implementation and datasets are available at https://github.com/NVlabs/FUNIT . <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.01723v2-abstract-full').style.display = 'none'; document.getElementById('1905.01723v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 September, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">The paper will be presented at the International Conference on Computer Vision (ICCV) 2019</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> ICCV 2019 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.08713">arXiv:1904.08713</a> <span> [<a href="https://arxiv.org/pdf/1904.08713">pdf</a>, <a href="https://arxiv.org/format/1904.08713">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201935729">10.1051/0004-6361/201935729 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spot evolution on LQ Hya during 2006--2017: temperature maps based on SOFIN and FIES data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cole-Kodikara%2C+E+M">Elizabeth M. Cole-Kodikara</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">Maarit J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/?searchtype=author&query=Ilyin%2C+I+V">Ilya V. Ilyin</a>, <a href="/search/?searchtype=author&query=Piskunov%2C+N">Nikolai Piskunov</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1904.08713v1-abstract-short" style="display: inline;"> Context. LQ Hya is one of the most frequently studied young solar analogue stars. Recently, it has been observed to show intriguing behaviour by analysing long-term photometry: during 2003--2009, a coherent spot structure migrating in the rotational frame has been reported by various authors, but since that time the star has entered a chaotic state where coherent structures seem to have disappeare… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.08713v1-abstract-full').style.display = 'inline'; document.getElementById('1904.08713v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.08713v1-abstract-full" style="display: none;"> Context. LQ Hya is one of the most frequently studied young solar analogue stars. Recently, it has been observed to show intriguing behaviour by analysing long-term photometry: during 2003--2009, a coherent spot structure migrating in the rotational frame has been reported by various authors, but since that time the star has entered a chaotic state where coherent structures seem to have disappeared and rapid phase jumps of the photometric minima occur irregularly over time. Aims. LQ Hya is one of the stars included in the SOFIN/FIES long-term monitoring campaign extending over 25 years. Here we publish new temperature maps for the star during 2006--2017, covering the chaotic state of the star. Methods. We use a Doppler imaging technique to derive surface temperature maps from high-resolution spectra. Results. From the mean temperatures of the Doppler maps we see a weak but systematic increase in the surface temperature of the star. This is consistent with the simultaneously increasing photometric magnitude. During nearly all observing seasons we see a high-latitude spot structure which is clearly nonaxisymmetric. The phase behaviour of this structure is very chaotic but agrees reasonably well with the photometry. Equatorial spots are also frequently seen, but many of them we interpret to be artefacts due to the poor to moderate phase coverage. Conclusions. Even during the chaotic phase of the star, the spot topology has remained very similar to the higher activity epochs with more coherent and long-lived spot structures: we see high-latitude and equatorial spot activity, the mid latitude range still being most often void of spots. We interpret the erratic jumps and drifts in phase of the photometric minima to be caused by changes in the high-latitude spot structure rather than the equatorial spots. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.08713v1-abstract-full').style.display = 'none'; document.getElementById('1904.08713v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 629, A120 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.06991">arXiv:1904.06991</a> <span> [<a href="https://arxiv.org/pdf/1904.06991">pdf</a>, <a href="https://arxiv.org/format/1904.06991">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> </div> </div> <p class="title is-5 mathjax"> Improved Precision and Recall Metric for Assessing Generative Models </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kynk%C3%A4%C3%A4nniemi%2C+T">Tuomas Kynk盲盲nniemi</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1904.06991v3-abstract-short" style="display: inline;"> The ability to automatically estimate the quality and coverage of the samples produced by a generative model is a vital requirement for driving algorithm research. We present an evaluation metric that can separately and reliably measure both of these aspects in image generation tasks by forming explicit, non-parametric representations of the manifolds of real and generated data. We demonstrate the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.06991v3-abstract-full').style.display = 'inline'; document.getElementById('1904.06991v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.06991v3-abstract-full" style="display: none;"> The ability to automatically estimate the quality and coverage of the samples produced by a generative model is a vital requirement for driving algorithm research. We present an evaluation metric that can separately and reliably measure both of these aspects in image generation tasks by forming explicit, non-parametric representations of the manifolds of real and generated data. We demonstrate the effectiveness of our metric in StyleGAN and BigGAN by providing several illustrative examples where existing metrics yield uninformative or contradictory results. Furthermore, we analyze multiple design variants of StyleGAN to better understand the relationships between the model architecture, training methods, and the properties of the resulting sample distribution. In the process, we identify new variants that improve the state-of-the-art. We also perform the first principled analysis of truncation methods and identify an improved method. Finally, we extend our metric to estimate the perceptual quality of individual samples, and use this to study latent space interpolations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.06991v3-abstract-full').style.display = 'none'; document.getElementById('1904.06991v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">NeurIPS 2019 final version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.10277">arXiv:1901.10277</a> <span> [<a href="https://arxiv.org/pdf/1901.10277">pdf</a>, <a href="https://arxiv.org/format/1901.10277">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Neural and Evolutionary Computing">cs.NE</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> High-Quality Self-Supervised Deep Image Denoising </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1901.10277v3-abstract-short" style="display: inline;"> We describe a novel method for training high-quality image denoising models based on unorganized collections of corrupted images. The training does not need access to clean reference images, or explicit pairs of corrupted images, and can thus be applied in situations where such data is unacceptably expensive or impossible to acquire. We build on a recent technique that removes the need for referen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.10277v3-abstract-full').style.display = 'inline'; document.getElementById('1901.10277v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.10277v3-abstract-full" style="display: none;"> We describe a novel method for training high-quality image denoising models based on unorganized collections of corrupted images. The training does not need access to clean reference images, or explicit pairs of corrupted images, and can thus be applied in situations where such data is unacceptably expensive or impossible to acquire. We build on a recent technique that removes the need for reference data by employing networks with a "blind spot" in the receptive field, and significantly improve two key aspects: image quality and training efficiency. Our result quality is on par with state-of-the-art neural network denoisers in the case of i.i.d. additive Gaussian noise, and not far behind with Poisson and impulse noise. We also successfully handle cases where parameters of the noise model are variable and/or unknown in both training and evaluation data. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.10277v3-abstract-full').style.display = 'none'; document.getElementById('1901.10277v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 29 January, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">NeurIPS 2019 final version</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.02013">arXiv:1812.02013</a> <span> [<a href="https://arxiv.org/pdf/1812.02013">pdf</a>, <a href="https://arxiv.org/ps/1812.02013">ps</a>, <a href="https://arxiv.org/format/1812.02013">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201834763">10.1051/0004-6361/201834763 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Starspot activity of HD 199178. Doppler images from 1994--2017 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Hackman%2C+T">Thomas Hackman</a>, <a href="/search/?searchtype=author&query=Ilyin%2C+I">Iya Ilyin</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">Jyri J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">Oleg Kochukhov</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">Maarit J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Piskunov%2C+N">Nikolai Piskunov</a>, <a href="/search/?searchtype=author&query=Willamo%2C+T">Teemu Willamo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1812.02013v2-abstract-short" style="display: inline;"> Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that canno… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.02013v2-abstract-full').style.display = 'inline'; document.getElementById('1812.02013v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.02013v2-abstract-full" style="display: none;"> Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For this research it is important to collect observation time series that are long enough to unravel both long- and short-term spot evolution. Doppler imaging is a very efficient method for studying spots of stars that cannot be angularly resolved. Aims. High-resolution spectral observations during 1994-2017 are analysed in order to reveal long- and short-term changes in the spot activity of the FK Comae-type subgiant HD 199178. Methods. Most of the observations were collected with the Nordic Optical Telescope. The Doppler imaging temperature maps were calculated using an inversion technique based on Tikhonov regularisation and utilising multiple spectral lines. Results. We present a unique series of 41 temperature maps spanning more than 23 years. All reliable images show a large cool spot region centred near the visible rotation pole. Some lower latitude cool features are also recovered, although the reliability of these is questionable. There is an expected anti-correlation between the mean surface temperature and the spot coverage. Using the Doppler images, we construct the equivalent of a solar butterfly diagram for HD 199178. Conclusions. HD 199178 clearly has a long-term large and cool spot structure at the rotational pole. This spot structure dominated the spot activity during the years 1994-2017. The size and position of the structure has evolved with time, with a gradual increase during the last years. The lack of lower latitude features prevents the determination of a possible differential rotation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.02013v2-abstract-full').style.display = 'none'; document.getElementById('1812.02013v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 7 figures, Astronomy and Astrophysics, parallel version of published article</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 625, A79 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1811.05330">arXiv:1811.05330</a> <span> [<a href="https://arxiv.org/pdf/1811.05330">pdf</a>, <a href="https://arxiv.org/ps/1811.05330">ps</a>, <a href="https://arxiv.org/format/1811.05330">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1051/0004-6361/201834562">10.1051/0004-6361/201834562 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Long-term spot monitoring of the young solar analogue V889 Her </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Willamo%2C+T">T. Willamo</a>, <a href="/search/?searchtype=author&query=Hackman%2C+T">T. Hackman</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+J">J. J. Lehtinen</a>, <a href="/search/?searchtype=author&query=K%C3%A4pyl%C3%A4%2C+M+J">M. J. K盲pyl盲</a>, <a href="/search/?searchtype=author&query=Ilyin%2C+I">I. Ilyin</a>, <a href="/search/?searchtype=author&query=Henry%2C+G+W">G. W. Henry</a>, <a href="/search/?searchtype=author&query=Jetsu%2C+L">L. Jetsu</a>, <a href="/search/?searchtype=author&query=Kochukhov%2C+O">O. Kochukhov</a>, <a href="/search/?searchtype=author&query=Piskunov%2C+N">N. Piskunov</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1811.05330v2-abstract-short" style="display: inline;"> Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. This gives crucial information of the underlying dynamo process. Comparisons with the solar cycle enable us to infer knowledge about how the solar dynamo has evolved during the Sun's lifetime. Here we study the correlatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.05330v2-abstract-full').style.display = 'inline'; document.getElementById('1811.05330v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1811.05330v2-abstract-full" style="display: none;"> Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. This gives crucial information of the underlying dynamo process. Comparisons with the solar cycle enable us to infer knowledge about how the solar dynamo has evolved during the Sun's lifetime. Here we study the correlation between photometric brightness variations, spottedness and mean temperature in V889 Her, a young solar analogue. Our data covers 18 years of spectroscopic and 25 years of photometric observations. We use Doppler imaging to derive temperature maps from high-resolution spectra. We use the Continuous Period Search method to retrieve mean V-magnitudes from photometric data. Our Doppler imaging maps show a persistent polar spot structure varying in strength. This structure is centered slightly off the rotational pole. The mean temperature derived from the maps shows an overall decreasing trend, as does the photometric mean brightness, until it reaches its minimum around 2017. The filling factor of cool spots, however, shows only a weak tendency to anti-correlate with the decreasing mean brightness. We interpret V889 Her to have entered into a grand maximum in its activity. The clear relation between the mean temperature of the Doppler imaging surface maps and the mean magnitude supports the reliability of the Doppler images. The lack of correlation between the mean magnitude and the spottedness may indicate that bright features in the Doppler images are real. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.05330v2-abstract-full').style.display = 'none'; document.getElementById('1811.05330v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 7 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> A&A 622, A170 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.06412">arXiv:1810.06412</a> <span> [<a href="https://arxiv.org/pdf/1810.06412">pdf</a>, <a href="https://arxiv.org/ps/1810.06412">ps</a>, <a href="https://arxiv.org/format/1810.06412">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="History and Philosophy of Physics">physics.hist-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Solar and Stellar Astrophysics">astro-ph.SR</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Popular Physics">physics.pop-ph</span> </div> </div> <p class="title is-5 mathjax"> Algol as Horus in the Cairo Calendar: the possible means and the motives of the observations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Porceddu%2C+S">Sebastian Porceddu</a>, <a href="/search/?searchtype=author&query=Jetsu%2C+L">Lauri Jetsu</a>, <a href="/search/?searchtype=author&query=Markkanen%2C+T">Tapio Markkanen</a>, <a href="/search/?searchtype=author&query=Lyytinen%2C+J">Joonas Lyytinen</a>, <a href="/search/?searchtype=author&query=Kajatkari%2C+P">Perttu Kajatkari</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jyri Lehtinen</a>, <a href="/search/?searchtype=author&query=Toivari-Viitala%2C+J">Jaana Toivari-Viitala</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.06412v1-abstract-short" style="display: inline;"> An ancient Egyptian Calendar of Lucky and Unlucky Days, the Cairo Calendar (CC), assigns luck with the period of 2.850 days. Previous astronomical, astrophysical and statistical analyses of CC support the idea that this was the period of the eclipsing binary Algol three millennia ago. However, next to nothing is known about who recorded Algol's period into CC and especially how. Here, we show that… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.06412v1-abstract-full').style.display = 'inline'; document.getElementById('1810.06412v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.06412v1-abstract-full" style="display: none;"> An ancient Egyptian Calendar of Lucky and Unlucky Days, the Cairo Calendar (CC), assigns luck with the period of 2.850 days. Previous astronomical, astrophysical and statistical analyses of CC support the idea that this was the period of the eclipsing binary Algol three millennia ago. However, next to nothing is known about who recorded Algol's period into CC and especially how. Here, we show that the ancient Egyptian scribes had the possible means and the motives for such astronomical observations. Their principles of describing celestial phenomena as activity of gods reveal why Algol received the title of Horus. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.06412v1-abstract-full').style.display = 'none'; document.getElementById('1810.06412v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 6 figures, accepted in Open Astronomy</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.02541">arXiv:1810.02541</a> <span> [<a href="https://arxiv.org/pdf/1810.02541">pdf</a>, <a href="https://arxiv.org/format/1810.02541">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> PPO-CMA: Proximal Policy Optimization with Covariance Matrix Adaptation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=H%C3%A4m%C3%A4l%C3%A4inen%2C+P">Perttu H盲m盲l盲inen</a>, <a href="/search/?searchtype=author&query=Babadi%2C+A">Amin Babadi</a>, <a href="/search/?searchtype=author&query=Ma%2C+X">Xiaoxiao Ma</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.02541v9-abstract-short" style="display: inline;"> Proximal Policy Optimization (PPO) is a highly popular model-free reinforcement learning (RL) approach. However, we observe that in a continuous action space, PPO can prematurely shrink the exploration variance, which leads to slow progress and may make the algorithm prone to getting stuck in local optima. Drawing inspiration from CMA-ES, a black-box evolutionary optimization method designed for r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.02541v9-abstract-full').style.display = 'inline'; document.getElementById('1810.02541v9-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.02541v9-abstract-full" style="display: none;"> Proximal Policy Optimization (PPO) is a highly popular model-free reinforcement learning (RL) approach. However, we observe that in a continuous action space, PPO can prematurely shrink the exploration variance, which leads to slow progress and may make the algorithm prone to getting stuck in local optima. Drawing inspiration from CMA-ES, a black-box evolutionary optimization method designed for robustness in similar situations, we propose PPO-CMA, a proximal policy optimization approach that adaptively expands the exploration variance to speed up progress. With only minor changes to PPO, our algorithm considerably improves performance in Roboschool continuous control benchmarks. Our results also show that PPO-CMA, as opposed to PPO, is significantly less sensitive to the choice of hyperparameters, allowing one to use it in complex movement optimization tasks without requiring tedious tuning. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.02541v9-abstract-full').style.display = 'none'; document.getElementById('1810.02541v9-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 3 November, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">This paper has been accepted to IEEE International Workshop on Machine Learning for Signal Processing (MLSP 2020). The arxiv version also includes an appendix that covers more results</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.02994">arXiv:1809.02994</a> <span> [<a href="https://arxiv.org/pdf/1809.02994">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/sciadv.aax9191">10.1126/sciadv.aax9191 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Efficient thermionic operation and phonon isolation by a semiconductor-superconductor junction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Mykk%C3%A4nen%2C+E">Emma Mykk盲nen</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J+S">Janne S. Lehtinen</a>, <a href="/search/?searchtype=author&query=Gr%C3%B6nberg%2C+L">Leif Gr枚nberg</a>, <a href="/search/?searchtype=author&query=Shchepetov%2C+A">Andrey Shchepetov</a>, <a href="/search/?searchtype=author&query=Timofeev%2C+A+V">Andrey V. Timofeev</a>, <a href="/search/?searchtype=author&query=Gunnarsson%2C+D">David Gunnarsson</a>, <a href="/search/?searchtype=author&query=Kemppinen%2C+A">Antti Kemppinen</a>, <a href="/search/?searchtype=author&query=Manninen%2C+A+J">Antti J. Manninen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1809.02994v1-abstract-short" style="display: inline;"> Control of heat flux at small length scales is crucial for numerous solid-state devices and systems. In addition to the thermal management of information and communication devices the mastering of heat transfer channels down to the nanoscale also enable, e.g., new memory concepts, high sensitivity detectors and sensors, energy harvesters and compact solid-state refrigerators. Electronic coolers an… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.02994v1-abstract-full').style.display = 'inline'; document.getElementById('1809.02994v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.02994v1-abstract-full" style="display: none;"> Control of heat flux at small length scales is crucial for numerous solid-state devices and systems. In addition to the thermal management of information and communication devices the mastering of heat transfer channels down to the nanoscale also enable, e.g., new memory concepts, high sensitivity detectors and sensors, energy harvesters and compact solid-state refrigerators. Electronic coolers and thermal detectors for electromagnetic radiation, especially, rely on the maximization of electro-thermal response and blockade of phonon transport. In this work, we propose and demonstrate that efficient electro-thermal operation and phonon transfer blocking can be achieved in a single solid-state thermionic junction. Our experimental demonstration relies on suspended semiconductor-superconductor junctions where the electro-thermal response arises from the superconducting energy gap, and the phonon blocking naturally results from the transmission bottleneck at the junction. We suspend different size degenerately doped silicon chips (up to macroscopic scale) directly from the junctions and cool these by biasing the junctions. The electronic cooling operation characteristics are accompanied by measurement and analysis of the thermal resistance components in the structures indicating the operation principle of phonon blocking in the junctions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.02994v1-abstract-full').style.display = 'none'; document.getElementById('1809.02994v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances 6 eaax9191 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1806.09397">arXiv:1806.09397</a> <span> [<a href="https://arxiv.org/pdf/1806.09397">pdf</a>, <a href="https://arxiv.org/format/1806.09397">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s42005-019-0225-6">10.1038/s42005-019-0225-6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nanobolometer with Ultralow Noise Equivalent Power </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kokkoniemi%2C+R">R. Kokkoniemi</a>, <a href="/search/?searchtype=author&query=Govenius%2C+J">J. Govenius</a>, <a href="/search/?searchtype=author&query=Vesterinen%2C+V">V. Vesterinen</a>, <a href="/search/?searchtype=author&query=Lake%2C+R+E">R. E. Lake</a>, <a href="/search/?searchtype=author&query=Gunyho%2C+A+M">A. M. Gunyho</a>, <a href="/search/?searchtype=author&query=Tan%2C+K+Y">K. Y. Tan</a>, <a href="/search/?searchtype=author&query=Simbierowicz%2C+S">S. Simbierowicz</a>, <a href="/search/?searchtype=author&query=Gr%C3%B6nberg%2C+L">L. Gr枚nberg</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">J. Lehtinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">M. Prunnila</a>, <a href="/search/?searchtype=author&query=Hassel%2C+J">J. Hassel</a>, <a href="/search/?searchtype=author&query=Saira%2C+O+-">O. -P. Saira</a>, <a href="/search/?searchtype=author&query=M%C3%B6tt%C3%B6nen%2C+M">M. M枚tt枚nen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1806.09397v2-abstract-short" style="display: inline;"> Since the introduction of bolometers more than a century ago, they have been applied in a broad spectrum of contexts ranging from security and the construction industry to particle physics and astronomy. However, emerging technologies and missions call for faster bolometers with lower noise. Here, we demonstrate a nanobolometer that exhibits roughly an order of magnitude lower noise equivalent pow… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.09397v2-abstract-full').style.display = 'inline'; document.getElementById('1806.09397v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1806.09397v2-abstract-full" style="display: none;"> Since the introduction of bolometers more than a century ago, they have been applied in a broad spectrum of contexts ranging from security and the construction industry to particle physics and astronomy. However, emerging technologies and missions call for faster bolometers with lower noise. Here, we demonstrate a nanobolometer that exhibits roughly an order of magnitude lower noise equivalent power, $20\textrm{ zW}/\sqrt{\textrm{Hz}}$, than previously reported for any bolometer. Importantly, it is more than an order of magnitude faster than other low-noise bolometers, with a time constant of 30 $渭$s at $60\textrm{ zW}/\sqrt{\textrm{Hz}}$. These results suggest a calorimetric energy resolution of $0.3\textrm{ zJ}=h\times 0.4$ THz with a time constant of 30 $渭$s. Thus the introduced nanobolometer is a promising candidate for future applications requiring extreme precision and speed such as those in astronomy and terahertz photon counting. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1806.09397v2-abstract-full').style.display = 'none'; document.getElementById('1806.09397v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.07307">arXiv:1805.07307</a> <span> [<a href="https://arxiv.org/pdf/1805.07307">pdf</a>, <a href="https://arxiv.org/format/1805.07307">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1088/1361-6668/aad4f2">10.1088/1361-6668/aad4f2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Flux-driven Josephson parametric amplifier for sub-GHz frequencies fabricated with side-wall passivated spacer junction technology </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Simbierowicz%2C+S">Slawomir Simbierowicz</a>, <a href="/search/?searchtype=author&query=Vesterinen%2C+V">Visa Vesterinen</a>, <a href="/search/?searchtype=author&query=Gr%C3%B6nberg%2C+L">Leif Gr枚nberg</a>, <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Janne Lehtinen</a>, <a href="/search/?searchtype=author&query=Prunnila%2C+M">Mika Prunnila</a>, <a href="/search/?searchtype=author&query=Hassel%2C+J">Juha Hassel</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.07307v1-abstract-short" style="display: inline;"> We present experimental results on a Josephson parametric amplifier tailored for readout of ultra-sensitive thermal microwave detectors. In particular, we discuss the impact of fabrication details on the performance. We show that the small volume of deposited dielectric materials enabled by the side-wall passivated spacer niobium junction technology leads to robust operation across a wide range of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.07307v1-abstract-full').style.display = 'inline'; document.getElementById('1805.07307v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.07307v1-abstract-full" style="display: none;"> We present experimental results on a Josephson parametric amplifier tailored for readout of ultra-sensitive thermal microwave detectors. In particular, we discuss the impact of fabrication details on the performance. We show that the small volume of deposited dielectric materials enabled by the side-wall passivated spacer niobium junction technology leads to robust operation across a wide range of operating temperatures up to 1.5 K. The flux-pumped amplifier has gain in excess of 20 dB in three-wave mixing and its center frequency is tunable between 540 MHz and 640 MHz. At 600 MHz, the amplifier adds 105 mK $\pm$ 9 mK of noise, as determined with the hot/cold source method. Phase-sensitive amplification is demonstrated with the device. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.07307v1-abstract-full').style.display = 'none'; document.getElementById('1805.07307v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.04189">arXiv:1803.04189</a> <span> [<a href="https://arxiv.org/pdf/1803.04189">pdf</a>, <a href="https://arxiv.org/format/1803.04189">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Computer Vision and Pattern Recognition">cs.CV</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">cs.LG</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Machine Learning">stat.ML</span> </div> </div> <p class="title is-5 mathjax"> Noise2Noise: Learning Image Restoration without Clean Data </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Lehtinen%2C+J">Jaakko Lehtinen</a>, <a href="/search/?searchtype=author&query=Munkberg%2C+J">Jacob Munkberg</a>, <a href="/search/?searchtype=author&query=Hasselgren%2C+J">Jon Hasselgren</a>, <a href="/search/?searchtype=author&query=Laine%2C+S">Samuli Laine</a>, <a href="/search/?searchtype=author&query=Karras%2C+T">Tero Karras</a>, <a href="/search/?searchtype=author&query=Aittala%2C+M">Miika Aittala</a>, <a href="/search/?searchtype=author&query=Aila%2C+T">Timo Aila</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.04189v3-abstract-short" style="display: inline;"> We apply basic statistical reasoning to signal reconstruction by machine learning -- learning to map corrupted observations to clean signals -- with a simple and powerful conclusion: it is possible to learn to restore images by only looking at corrupted examples, at performance at and sometimes exceeding training using clean data, without explicit image priors or likelihood models of the corruptio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.04189v3-abstract-full').style.display = 'inline'; document.getElementById('1803.04189v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.04189v3-abstract-full" style="display: none;"> We apply basic statistical reasoning to signal reconstruction by machine learning -- learning to map corrupted observations to clean signals -- with a simple and powerful conclusion: it is possible to learn to restore images by only looking at corrupted examples, at performance at and sometimes exceeding training using clean data, without explicit image priors or likelihood models of the corruption. In practice, we show that a single model learns photographic noise removal, denoising synthetic Monte Carlo images, and reconstruction of undersampled MRI scans -- all corrupted by different processes -- based on noisy data only. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.04189v3-abstract-full').style.display = 'none'; document.getElementById('1803.04189v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 29 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Added link to official implementation and updated MRI results to match it</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Lehtinen%2C+J&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul 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