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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=Paraoanu%2C+G+S&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S&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/2403.15342">arXiv:2403.15342</a> <span> [<a href="https://arxiv.org/pdf/2403.15342">pdf</a>, <a href="https://arxiv.org/format/2403.15342">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"> On the validity of the rotating wave approximation for coupled harmonic oscillators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Heib%2C+T">Tim Heib</a>, <a href="/search/?searchtype=author&query=Lageyre%2C+P">Paul Lageyre</a>, <a href="/search/?searchtype=author&query=Ferreri%2C+A">Alessandro Ferreri</a>, <a href="/search/?searchtype=author&query=Wilhelm%2C+F+K">Frank K. Wilhelm</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Burgarth%2C+D">Daniel Burgarth</a>, <a href="/search/?searchtype=author&query=Schell%2C+A+W">Andreas Wolfgang Schell</a>, <a href="/search/?searchtype=author&query=Bruschi%2C+D+E">David Edward Bruschi</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="2403.15342v1-abstract-short" style="display: inline;"> In this work we study the validity of the rotating wave approximation of an ideal system composed of two harmonic oscillators evolving with a quadratic Hamiltonian and arbitrarily strong interaction. We solve the dynamics analytically by employing tools from symplectic geometry. We focus on systems with initial Gaussian states and quantify exactly the deviation between the state obtained through t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.15342v1-abstract-full').style.display = 'inline'; document.getElementById('2403.15342v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2403.15342v1-abstract-full" style="display: none;"> In this work we study the validity of the rotating wave approximation of an ideal system composed of two harmonic oscillators evolving with a quadratic Hamiltonian and arbitrarily strong interaction. We solve the dynamics analytically by employing tools from symplectic geometry. We focus on systems with initial Gaussian states and quantify exactly the deviation between the state obtained through the rotating approximation and the state obtained through the full evolution, therefore providing an answer for all values of the coupling. We find that the squeezing present in the full Hamiltonian and in the initial state governs the deviation from the approximated evolution. Furthermore, we also show that the rotating wave approximation is recovered for resonant frequencies and vanishing coupling to frequency ratio. Finally, we give a general proof of the rotating wave approximation and estimate its convergence on Fock states. Applications and potential physical implementations are also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2403.15342v1-abstract-full').style.display = 'none'; document.getElementById('2403.15342v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">34 pages, 3 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/2402.10833">arXiv:2402.10833</a> <span> [<a href="https://arxiv.org/pdf/2402.10833">pdf</a>, <a href="https://arxiv.org/format/2402.10833">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> </div> <p class="title is-5 mathjax"> Observation of the two-photon Landau-Zener-St眉ckelberg-Majorana effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bj%C3%B6rkman%2C+I">Isak Bj枚rkman</a>, <a href="/search/?searchtype=author&query=Kuzmanovi%C4%87%2C+M">Marko Kuzmanovi膰</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2402.10833v1-abstract-short" style="display: inline;"> Second-order processes introduce nonlinearities in quantum dynamics, unlocking a totally unexpected area of control operations. Here we show that the well-known Landau-Zener-St眉ckelberg-Majorana (LZSM) transition can be driven by a virtual process in a three-level system whereby two photons from a drive with linearly-modulated phase create excitations onto the third level while avoiding completely… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.10833v1-abstract-full').style.display = 'inline'; document.getElementById('2402.10833v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.10833v1-abstract-full" style="display: none;"> Second-order processes introduce nonlinearities in quantum dynamics, unlocking a totally unexpected area of control operations. Here we show that the well-known Landau-Zener-St眉ckelberg-Majorana (LZSM) transition can be driven by a virtual process in a three-level system whereby two photons from a drive with linearly-modulated phase create excitations onto the third level while avoiding completely the first level. We implement this experimentally in a transmon qubit achieving a population transfer of $98\%$, limited by relaxation. We predict and observe experimentally the doubling of the LZSM velocity. The observation of this effect is made possible by the nearly-exact cancellation of the two-photon ac Stark shift when the third transition is included. Furthermore, we demonstrate considerable robustness to offsets in frequency and amplitude, both in theory and experimentally. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.10833v1-abstract-full').style.display = 'none'; document.getElementById('2402.10833v1-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> 16 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2401.17438">arXiv:2401.17438</a> <span> [<a href="https://arxiv.org/pdf/2401.17438">pdf</a>, <a href="https://arxiv.org/format/2401.17438">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</span> </div> </div> <p class="title is-5 mathjax"> Quantum simulation of the pseudo-Hermitian Landau-Zener-St眉ckelberg-Majorana effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kivel%C3%A4%2C+F">Feliks Kivel盲</a>, <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2401.17438v2-abstract-short" style="display: inline;"> While the Hamiltonians used in standard quantum mechanics are Hermitian, it is also possible to extend the theory to non-Hermitian Hamiltonians. Particularly interesting are non-Hermitian Hamiltonians satisfying parity-time (PT) symmetry, or more generally pseudo-Hermiticity, since such non-Hermitian Hamiltonians can still exhibit real eigenvalues. In this work, we present a quantum simulation of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.17438v2-abstract-full').style.display = 'inline'; document.getElementById('2401.17438v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2401.17438v2-abstract-full" style="display: none;"> While the Hamiltonians used in standard quantum mechanics are Hermitian, it is also possible to extend the theory to non-Hermitian Hamiltonians. Particularly interesting are non-Hermitian Hamiltonians satisfying parity-time (PT) symmetry, or more generally pseudo-Hermiticity, since such non-Hermitian Hamiltonians can still exhibit real eigenvalues. In this work, we present a quantum simulation of the time-dependent non-Hermitian non-PT-symmetric Hamiltonian used in a pseudo-Hermitian extension of the Landau-Zener-St眉ckelberg-Majorana (LZSM) model. The simulation is implemented on a superconducting processor by using Naimark dilation to transform a non-Hermitian Hamiltonian for one qubit into a Hermitian Hamiltonian for a qubit and an ancilla; postselection on the ancilla state ensures that the qubit undergoes nonunitary time-evolution corresponding to the original non-Hermitian Hamiltonian. We observe properties such as the dependence of transition rates on time and the replacement of conservation of total probability by other dynamical invariants in agreement with predictions based on a theoretical treatment of the pseudo-Hermitian LZSM system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2401.17438v2-abstract-full').style.display = 'none'; document.getElementById('2401.17438v2-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> 2 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">12 pages, 7 figures. Changes from the previous version: Added a definition of the U quantum gate and additional details about the initialization of the quantum circuits. Improved some aspects of notation. Changed equation 30 (previously equation 28) slightly to emphasize that it only applies to basis states, not arbitrary states. Fixed some typos</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.17190">arXiv:2312.17190</a> <span> [<a href="https://arxiv.org/pdf/2312.17190">pdf</a>, <a href="https://arxiv.org/format/2312.17190">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 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/PhysRevA.110.032404">10.1103/PhysRevA.110.032404 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coherent interaction-free detection of noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=McCord%2C+J+J">John J. McCord</a>, <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2312.17190v2-abstract-short" style="display: inline;"> The measurement and characterization of noise is a flourishing area of research in mesoscopic physics. In this work, we propose interaction-free measurements as a noise-detection technique, exploring two conceptually different schemes: the coherent and the projective realizations. These detectors consist of a qutrit whose second transition is resonantly coupled to an oscillatory field that may hav… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.17190v2-abstract-full').style.display = 'inline'; document.getElementById('2312.17190v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.17190v2-abstract-full" style="display: none;"> The measurement and characterization of noise is a flourishing area of research in mesoscopic physics. In this work, we propose interaction-free measurements as a noise-detection technique, exploring two conceptually different schemes: the coherent and the projective realizations. These detectors consist of a qutrit whose second transition is resonantly coupled to an oscillatory field that may have noise in amplitude or phase. For comparison, we consider a more standard detector previously discussed in this context: a qubit coupled in a similar way to the noise source. We find that the qutrit scheme offers clear advantages, allowing precise detection and characterization of the noise, while the qubit does not. Finally, we study the signature of noise correlations in the detector's signal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.17190v2-abstract-full').style.display = 'none'; document.getElementById('2312.17190v2-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 September, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 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">15 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 110, 032404 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.04707">arXiv:2312.04707</a> <span> [<a href="https://arxiv.org/pdf/2312.04707">pdf</a>, <a href="https://arxiv.org/format/2312.04707">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"> Fault-tolerant one-way noiseless amplification for microwave bosonic quantum information processing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Khalifa%2C+H">Hany Khalifa</a>, <a href="/search/?searchtype=author&query=J%C3%A4ntti%2C+R">Riku J盲ntti</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2312.04707v1-abstract-short" style="display: inline;"> Microwave quantum information networks require reliable transmission of single photon propagating modes over lossy channels. In this article we propose a microwave noise-less linear amplifier (NLA) suitable to circumvent the losses incurred by a flying photon undergoing an amplitude damping channel (ADC). The proposed model is constructed by engineering a simple one-dimensional four node cluster s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04707v1-abstract-full').style.display = 'inline'; document.getElementById('2312.04707v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.04707v1-abstract-full" style="display: none;"> Microwave quantum information networks require reliable transmission of single photon propagating modes over lossy channels. In this article we propose a microwave noise-less linear amplifier (NLA) suitable to circumvent the losses incurred by a flying photon undergoing an amplitude damping channel (ADC). The proposed model is constructed by engineering a simple one-dimensional four node cluster state. Contrary to conventional NLAs based on quantum scissors (QS), single photon amplification is realized without the need for photon number resolving detectors (PNRDs). Entanglement between nodes comprising the device's cluster is achieved by means of a controlled phase gate (CPHASE). Furthermore, photon measurements are implemented by quantum non demolition detectors (QNDs), which are currently available as a part of circuit quantum electrodynamics (cQED) toolbox. We analyze the performance of our device practically by considering detection inefficiency and dark count probability. We further examine the potential usage of our device in low power quantum sensing applications and remote secret key generation (SKG). Specifically, we demonstrate the device's ability to prepare loss-free resources offline, and its capacity to overcome the repeater-less bound of SKG. We compare the performance of our device against a QS-NLA for the aforementioned applications, and highlight explicitly the operating conditions under which our device can outperform a QS-NLA. The proposed device is also suitable for applications in the optical domain. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.04707v1-abstract-full').style.display = 'none'; document.getElementById('2312.04707v1-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> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.13353">arXiv:2308.13353</a> <span> [<a href="https://arxiv.org/pdf/2308.13353">pdf</a>, <a href="https://arxiv.org/format/2308.13353">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"> High-fidelity robust qubit control by phase-modulated pulses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kuzmanovi%C4%87%2C+M">Marko Kuzmanovi膰</a>, <a href="/search/?searchtype=author&query=Bj%C3%B6rkman%2C+I">Isak Bj枚rkman</a>, <a href="/search/?searchtype=author&query=McCord%2C+J+J">John J. McCord</a>, <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2308.13353v2-abstract-short" style="display: inline;"> We present a set of robust and high-fidelity pulses that realize paradigmatic operations such as the transfer of the ground state population into the excited state and arbitrary $X/Y$ rotations on the Bloch sphere. These pulses are based on the phase modulation of the control field. We implement these operations on a transmon qubit, demonstrating resilience against deviations in the drive amplitud… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13353v2-abstract-full').style.display = 'inline'; document.getElementById('2308.13353v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.13353v2-abstract-full" style="display: none;"> We present a set of robust and high-fidelity pulses that realize paradigmatic operations such as the transfer of the ground state population into the excited state and arbitrary $X/Y$ rotations on the Bloch sphere. These pulses are based on the phase modulation of the control field. We implement these operations on a transmon qubit, demonstrating resilience against deviations in the drive amplitude of more than $\approx 20\%$ and/or detuning from the qubit transition frequency in the order of $10~\mathrm{MHz}$. The concept and modulation scheme is straightforward to implement and it is compatible with other quantum-technology experimental platforms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.13353v2-abstract-full').style.display = 'none'; document.getElementById('2308.13353v2-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 September, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.07084">arXiv:2308.07084</a> <span> [<a href="https://arxiv.org/pdf/2308.07084">pdf</a>, <a href="https://arxiv.org/format/2308.07084">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"> Microwave photon detection at parametric criticality </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Petrovnin%2C+K">Kirill Petrovnin</a>, <a href="/search/?searchtype=author&query=Wang%2C+J">Jiaming Wang</a>, <a href="/search/?searchtype=author&query=Perelshtein%2C+M">Michael Perelshtein</a>, <a href="/search/?searchtype=author&query=Hakonen%2C+P">Pertti Hakonen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2308.07084v3-abstract-short" style="display: inline;"> The detection of microwave fields at single-photon power levels is a much sought-after technology, with practical applications in nanoelectronics and quantum information science. Here we demonstrate a simple yet powerful criticality-enhanced method of microwave photon detection by operating a magnetic-field tunable Kerr Josephson parametric amplifier near a first-order quantum phase transition. We… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.07084v3-abstract-full').style.display = 'inline'; document.getElementById('2308.07084v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.07084v3-abstract-full" style="display: none;"> The detection of microwave fields at single-photon power levels is a much sought-after technology, with practical applications in nanoelectronics and quantum information science. Here we demonstrate a simple yet powerful criticality-enhanced method of microwave photon detection by operating a magnetic-field tunable Kerr Josephson parametric amplifier near a first-order quantum phase transition. We obtain a 73% efficiency and a dark-count rate of 167 kHz, corresponding to a responsivity of $1.3 \times 10^{17}~\mathrm{W}^{-1}$ and noise-equivalent power of 3.28 zW/$\sqrt{\rm Hz}$. We verify the single-photon operation by extracting the Poissonian statistics of a coherent probe signal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.07084v3-abstract-full').style.display = 'none'; document.getElementById('2308.07084v3-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 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">The focused version, reorganized at the request of the editor to fit the journal size limits</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.05214">arXiv:2307.05214</a> <span> [<a href="https://arxiv.org/pdf/2307.05214">pdf</a>, <a href="https://arxiv.org/format/2307.05214">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 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/PhysRevResearch.5.033012">10.1103/PhysRevResearch.5.033012 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Theory of coherent interaction-free detection of pulses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=McCord%2C+J+J">John J. McCord</a>, <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2307.05214v1-abstract-short" style="display: inline;"> Quantum physics allows an object to be detected even in the absence of photon absorption, by the use of so-called interaction-free measurements. We provide a formulation of this protocol using a three-level system, where the object to be detected is a pulse coupled resonantly into the second transition. In the original formulation of interaction-free measurements, the absorption is associated with… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.05214v1-abstract-full').style.display = 'inline'; document.getElementById('2307.05214v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.05214v1-abstract-full" style="display: none;"> Quantum physics allows an object to be detected even in the absence of photon absorption, by the use of so-called interaction-free measurements. We provide a formulation of this protocol using a three-level system, where the object to be detected is a pulse coupled resonantly into the second transition. In the original formulation of interaction-free measurements, the absorption is associated with a projection operator onto the third state. We perform an in-depth analytical and numerical analysis of the coherent protocol, where coherent interaction between the object and the detector replaces the projective operators, resulting in higher detection efficiencies. We provide approximate asymptotic analytical results to support this finding. We find that our protocol reaches the Heisenberg limit when evaluating the Fisher information at small strengths of the pulses we aim to detect -- in contrast to the projective protocol that can only reach the standard quantum limit. We also demonstrate that the coherent protocol remains remarkably robust under errors such as pulse rotation phases and strengths, the effect of relaxation rates and detunings, as well as different thermalized initial states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.05214v1-abstract-full').style.display = 'none'; document.getElementById('2307.05214v1-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">17 pages, 13 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, 033012 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2307.01014">arXiv:2307.01014</a> <span> [<a href="https://arxiv.org/pdf/2307.01014">pdf</a>, <a href="https://arxiv.org/format/2307.01014">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"> Microwave Gaussian quantum sensing with a CNOT gate receiver </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Khalifa%2C+H">Hany Khalifa</a>, <a href="/search/?searchtype=author&query=Petrovnin%2C+K">Kirill Petrovnin</a>, <a href="/search/?searchtype=author&query=J%C3%A4ntti%2C+R">Riku J盲ntti</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2307.01014v2-abstract-short" style="display: inline;"> In quantum illumination (QI) the non-classical correlations between continuous variable (CV) entangled modes of radiation are exploited to detect the presence of a target embedded in thermal noise. The extreme environment where QI outperforms its optimal classical counterpart suggests that applications in the microwave domain would benefit the most from this new sensing paradigm. However all the p… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01014v2-abstract-full').style.display = 'inline'; document.getElementById('2307.01014v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2307.01014v2-abstract-full" style="display: none;"> In quantum illumination (QI) the non-classical correlations between continuous variable (CV) entangled modes of radiation are exploited to detect the presence of a target embedded in thermal noise. The extreme environment where QI outperforms its optimal classical counterpart suggests that applications in the microwave domain would benefit the most from this new sensing paradigm. However all the proposed QI receivers rely on ideal photon counters or detectors, which are not currently feasible in the microwave domain. Here we propose a new QI receiver that utilizes a CV controlled not gate (CNOT) in order to perform a joint measurement on a target return and its retained twin. Unlike other QI receivers, the entire detection process is carried out by homodyne measurements and square-law detectors. The receiver exploits two squeezed ancillary modes as a part of the gate's operation. These extra resources are prepared offline and their overall gain is controlled passively by a single beamsplitter parameter. We compare our model to other QI receivers and demonstrate its operation regime where it outperforms others and achieves optimal performance. Although the main focus of this study is microwave quantum sensing applications, our proposed device can be built as well in the optical domain, thus rendering it as a new addition to the quantum sensing toolbox in a wider sense. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2307.01014v2-abstract-full').style.display = 'none'; document.getElementById('2307.01014v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.05200">arXiv:2306.05200</a> <span> [<a href="https://arxiv.org/pdf/2306.05200">pdf</a>, <a href="https://arxiv.org/format/2306.05200">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</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/10.1140/epjs/s11734-023-00989-0">10.1140/epjs/s11734-023-00989-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Integrated conversion and photodetection of virtual photons in an ultrastrongly coupled superconducting quantum circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Giannelli%2C+L">Luigi Giannelli</a>, <a href="/search/?searchtype=author&query=Anfuso%2C+G">Giorgio Anfuso</a>, <a href="/search/?searchtype=author&query=Grajcar%2C+M">Miroslav Grajcar</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">Elisabetta Paladino</a>, <a href="/search/?searchtype=author&query=Falci%2C+G">Giuseppe Falci</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="2306.05200v3-abstract-short" style="display: inline;"> The ground-state of an artificial atom ultrastrongly coupled to quantized modes is entangled and contains an arbitrary number of virtual photons. The problem of their detection has been raised since the very birth of the field but despite the theoretical efforts still awaits experimental demonstration. Recently experimental problems have been addressed in detail showing that they can be overcome b… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05200v3-abstract-full').style.display = 'inline'; document.getElementById('2306.05200v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.05200v3-abstract-full" style="display: none;"> The ground-state of an artificial atom ultrastrongly coupled to quantized modes is entangled and contains an arbitrary number of virtual photons. The problem of their detection has been raised since the very birth of the field but despite the theoretical efforts still awaits experimental demonstration. Recently experimental problems have been addressed in detail showing that they can be overcome by combining an unconventional design of the artificial atom with advanced coherent control. In this work we study a simple scheme of control-integrated continuous measurement which makes remarkably favourable the tradeoff between measurement efficiency and backaction showing that the unambiguous detection of virtual photons can be achieved within state-of-the art quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.05200v3-abstract-full').style.display = 'none'; document.getElementById('2306.05200v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 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">10 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> The European Physical Journal Special Topics 232, 3387-3392 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2302.10973">arXiv:2302.10973</a> <span> [<a href="https://arxiv.org/pdf/2302.10973">pdf</a>, <a href="https://arxiv.org/format/2302.10973">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</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/PhysRevResearch.6.013008">10.1103/PhysRevResearch.6.013008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Detecting virtual photons in ultrastrongly coupled superconducting quantum circuits </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Giannelli%2C+L">Luigi Giannelli</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">Elisabetta Paladino</a>, <a href="/search/?searchtype=author&query=Grajcar%2C+M">Miroslav Grajcar</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Falci%2C+G">Giuseppe Falci</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="2302.10973v3-abstract-short" style="display: inline;"> Light-matter interaction and understanding the fundamental physics behind is essential for emerging quantum technologies. Solid-state devices may explore new regimes where coupling strengths are "ultrastrong", i.e., comparable to the energies of the subsystems. New exotic phenomena occur the common root of many of them being the fact that the entangled vacuum contains virtual photons. They herald… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.10973v3-abstract-full').style.display = 'inline'; document.getElementById('2302.10973v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2302.10973v3-abstract-full" style="display: none;"> Light-matter interaction and understanding the fundamental physics behind is essential for emerging quantum technologies. Solid-state devices may explore new regimes where coupling strengths are "ultrastrong", i.e., comparable to the energies of the subsystems. New exotic phenomena occur the common root of many of them being the fact that the entangled vacuum contains virtual photons. They herald the lack of conservation of the number of excitations which is the witness of ultrastrong coupling breaking the U(1) symmetry. Despite more than a decade of research, the detection of ground-state virtual photons still awaits demonstration. In this work, we recognize the "conspiring" set of experimental challenges and show how to overcome them, thus providing a solution to this long-standing problem. We find that combining a superinductor-based unconventional "light fluxonium" qudit and coherent control yields a highly efficient, faithful, and selective conversion of virtual photons into real ones. This enables their detection with resources available to present-day quantum technologies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2302.10973v3-abstract-full').style.display = 'none'; document.getElementById('2302.10973v3-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 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 21 February, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">16 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physical Review Research 6, 013008 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.05271">arXiv:2204.05271</a> <span> [<a href="https://arxiv.org/pdf/2204.05271">pdf</a>, <a href="https://arxiv.org/format/2204.05271">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 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/10.1088/1361-6455/ac7fcc">10.1088/1361-6455/ac7fcc <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Perfect stimulated Raman adiabatic passage with imperfect finite-time pulses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2204.05271v2-abstract-short" style="display: inline;"> We present a well-tailored sequence of two Gaussian-pulsed drives that achieves perfect population transfer in STImulated Raman Adiabatic Passage (STIRAP). We give a theoretical analysis of the optimal truncation and relative placement of the Stokes and pump pulses. Further, we obtain the power and the duration of the protocol for a given pulse width. Importantly, the duration of the protocol requ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05271v2-abstract-full').style.display = 'inline'; document.getElementById('2204.05271v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.05271v2-abstract-full" style="display: none;"> We present a well-tailored sequence of two Gaussian-pulsed drives that achieves perfect population transfer in STImulated Raman Adiabatic Passage (STIRAP). We give a theoretical analysis of the optimal truncation and relative placement of the Stokes and pump pulses. Further, we obtain the power and the duration of the protocol for a given pulse width. Importantly, the duration of the protocol required to attain a desired value of fidelity depends only logarithmically on the infidelity. Subject to optimal truncation of the drives and with reference to the point of fastest transfer, we obtain a new adiabaticity criteria, which is remarkably simple and effective. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.05271v2-abstract-full').style.display = 'none'; document.getElementById('2204.05271v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">7 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Phys. B: At. Mol. Opt. Phys.55 174001 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.01657">arXiv:2204.01657</a> <span> [<a href="https://arxiv.org/pdf/2204.01657">pdf</a>, <a href="https://arxiv.org/format/2204.01657">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 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/s41467-022-35049-z">10.1038/s41467-022-35049-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coherent interaction-free detection of microwave pulses with a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=McCord%2C+J+J">John J. McCord</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2204.01657v2-abstract-short" style="display: inline;"> The interaction-free measurement is a fundamental quantum effect whereby the presence of a photosensitive object is determined without irreversible photon absorption. Here we propose the concept of coherent interaction-free detection and demonstrate it experimentally using a three-level superconducting transmon circuit. In contrast to standard interaction-free measurement setups, where the dynamic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01657v2-abstract-full').style.display = 'inline'; document.getElementById('2204.01657v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.01657v2-abstract-full" style="display: none;"> The interaction-free measurement is a fundamental quantum effect whereby the presence of a photosensitive object is determined without irreversible photon absorption. Here we propose the concept of coherent interaction-free detection and demonstrate it experimentally using a three-level superconducting transmon circuit. In contrast to standard interaction-free measurement setups, where the dynamics involves a series of projection operations, our protocol employs a fully coherent evolution that results, surprisingly, in a higher probability of success. We show that it is possible to ascertain the presence of a microwave pulse resonant with the second transition of the transmon, while at the same time avoid exciting the device onto the third level. Experimentally, this is done by using a series of Ramsey microwave pulses coupled into the first transition and monitoring the ground-state population. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.01657v2-abstract-full').style.display = 'none'; document.getElementById('2204.01657v2-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 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 4 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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, 20 figures. Comments are welcome!</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat Commun 13, 7528 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.12073">arXiv:2203.12073</a> <span> [<a href="https://arxiv.org/pdf/2203.12073">pdf</a>, <a href="https://arxiv.org/format/2203.12073">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 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/10.1098/rsta.2021.0274">10.1098/rsta.2021.0274 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental demonstration of robustness under scaling errors for superadiabatic population transfer in a superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2203.12073v2-abstract-short" style="display: inline;"> We study experimentally and theoretically the transfer of population between the ground state and the second excited state in a transmon circuit by the use of superadiabatic stimulated Raman adiabatic passage (saSTIRAP). We show that the transfer is remarkably resilient against variations in the amplitudes of the pulses (scaling errors), thus demostrating that the superadiabatic process inherits c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.12073v2-abstract-full').style.display = 'inline'; document.getElementById('2203.12073v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.12073v2-abstract-full" style="display: none;"> We study experimentally and theoretically the transfer of population between the ground state and the second excited state in a transmon circuit by the use of superadiabatic stimulated Raman adiabatic passage (saSTIRAP). We show that the transfer is remarkably resilient against variations in the amplitudes of the pulses (scaling errors), thus demostrating that the superadiabatic process inherits certain robustness features from the adiabatic one. In particular, we put in evidence a new plateau that appears at high values of the counterdiabatic pulse strength, which goes beyond the usual framework of saSTIRAP. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.12073v2-abstract-full').style.display = 'none'; document.getElementById('2203.12073v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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">9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phil. Trans. R. Soc. A., 380: 20210274 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.09247">arXiv:2203.09247</a> <span> [<a href="https://arxiv.org/pdf/2203.09247">pdf</a>, <a href="https://arxiv.org/format/2203.09247">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 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/10.1002/qute.202200031">10.1002/qute.202200031 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Generation and structuring of multipartite entanglement in Josephson parametric system </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Petrovnin%2C+K+V">K. V. Petrovnin</a>, <a href="/search/?searchtype=author&query=Perelshtein%2C+M+R">M. R. Perelshtein</a>, <a href="/search/?searchtype=author&query=Korkalainen%2C+T">T. Korkalainen</a>, <a href="/search/?searchtype=author&query=Vesterinen%2C+V">V. Vesterinen</a>, <a href="/search/?searchtype=author&query=Lilja%2C+I">I. Lilja</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Hakonen%2C+P+J">P. J. 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="2203.09247v2-abstract-short" style="display: inline;"> Quantum correlations are a vital resource in advanced information processing based on quantum phenomena. Remarkably, the vacuum state of a quantum field may act as a key element for the generation of multipartite quantum entanglement. In this work, we achieve generation of genuine tripartite entangled state and its control by the use of the phase difference between two continuous pump tones. We de… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09247v2-abstract-full').style.display = 'inline'; document.getElementById('2203.09247v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.09247v2-abstract-full" style="display: none;"> Quantum correlations are a vital resource in advanced information processing based on quantum phenomena. Remarkably, the vacuum state of a quantum field may act as a key element for the generation of multipartite quantum entanglement. In this work, we achieve generation of genuine tripartite entangled state and its control by the use of the phase difference between two continuous pump tones. We demonstrate control of the subspaces of the covariance matrix for tripartite bisqueezed state. Furthermore, by optimizing the phase relationships in a three-tone pumping scheme we explore genuine quadripartite entanglement of a \textit{generalized} H-graph state ($\mathscr{\tilde{H}}$-graph). Our scheme provides a comprehensive control toolbox for the entanglement structure and allows us to demonstrate, for first time to our knowledge, genuine quadripartite entanglement of microwave modes. All experimental results are verified with numerical simulations of the nonlinear quantum Langevin equation. We envision that quantum resources facilitated by multi-pump configurations offer enhanced prospects for quantum data processing using parametric microwave cavities. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.09247v2-abstract-full').style.display = 'none'; document.getElementById('2203.09247v2-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, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 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">Journal ref:</span> Advanced Quantum Technologies 6.1 (2023): 2200031 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2112.07453">arXiv:2112.07453</a> <span> [<a href="https://arxiv.org/pdf/2112.07453">pdf</a>, <a href="https://arxiv.org/format/2112.07453">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 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/10.1016/j.physleta.2022.128054">10.1016/j.physleta.2022.128054 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A Tutorial on Optimal Control and Reinforcement Learning methods for Quantum Technologies </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Giannelli%2C+L">Luigi Giannelli</a>, <a href="/search/?searchtype=author&query=Sgroi%2C+S">Sofia Sgroi</a>, <a href="/search/?searchtype=author&query=Brown%2C+J">Jonathon Brown</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Paternostro%2C+M">Mauro Paternostro</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">Elisabetta Paladino</a>, <a href="/search/?searchtype=author&query=Falci%2C+G">Giuseppe Falci</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="2112.07453v4-abstract-short" style="display: inline;"> Quantum Optimal Control is an established field of research which is necessary for the development of Quantum Technologies. In recent years, Machine Learning techniques have been proved usefull to tackle a variety of quantum problems. In particular, Reinforcement Learning has been employed to address typical problems of control of quantum systems. In this tutorial we introduce the methods of Qua… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.07453v4-abstract-full').style.display = 'inline'; document.getElementById('2112.07453v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2112.07453v4-abstract-full" style="display: none;"> Quantum Optimal Control is an established field of research which is necessary for the development of Quantum Technologies. In recent years, Machine Learning techniques have been proved usefull to tackle a variety of quantum problems. In particular, Reinforcement Learning has been employed to address typical problems of control of quantum systems. In this tutorial we introduce the methods of Quantum Optimal Control and Reinforcement Learning by applying them to the problem of three-level population transfer. The jupyter notebooks to reproduce some of our results are open-sourced and available on github. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2112.07453v4-abstract-full').style.display = 'none'; document.getElementById('2112.07453v4-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, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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, 11 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Physics Letters A 434, 128054 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.12044">arXiv:2111.12044</a> <span> [<a href="https://arxiv.org/pdf/2111.12044">pdf</a>, <a href="https://arxiv.org/format/2111.12044">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 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/10.1063/5.0054871">10.1063/5.0054871 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum process tomography of adiabatic and superadiabatic stimulated Raman passage </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2111.12044v1-abstract-short" style="display: inline;"> Quantum control methods for three-level systems have become recently an important direction of research in quantum information science and technology. Here we present numerical simulations using realistic experimental parameters for quantum process tomography in STIRAP (stimulated Raman adiabatic passage) and saSTIRAP (superadiabatic STIRAP). Specifically, we identify a suitable basis in the opera… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12044v1-abstract-full').style.display = 'inline'; document.getElementById('2111.12044v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.12044v1-abstract-full" style="display: none;"> Quantum control methods for three-level systems have become recently an important direction of research in quantum information science and technology. Here we present numerical simulations using realistic experimental parameters for quantum process tomography in STIRAP (stimulated Raman adiabatic passage) and saSTIRAP (superadiabatic STIRAP). Specifically, we identify a suitable basis in the operator space as the identity operator together with the 8 Gell-Mann operators, and we calculate the corresponding process matrices, which have $9\times 9=81$ elements. We discuss these results for the ideal decoherence-free case, as well as for the experimentally-relevant case with decoherence included. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12044v1-abstract-full').style.display = 'none'; document.getElementById('2111.12044v1-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 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">Journal ref:</span> AIP Conference Proceedings 2362, 030004 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.12036">arXiv:2111.12036</a> <span> [<a href="https://arxiv.org/pdf/2111.12036">pdf</a>, <a href="https://arxiv.org/format/2111.12036">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 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/s42005-021-00534-2">10.1038/s42005-021-00534-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum simulation of parity-time symmetry breaking with a superconducting quantum processor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Melnikov%2C+A+A">Artem A. Melnikov</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2111.12036v1-abstract-short" style="display: inline;"> The observation of genuine quantum effects in systems governed by non-Hermitian Hamiltonians has been an outstanding challenge in the field. Here we simulate the evolution under such Hamiltonians in the quantum regime on a superconducting quantum processor by using a dilation procedure involving an ancillary qubit. We observe the parity-time ($\mathcal{PT}$)-symmetry breaking phase transition at t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12036v1-abstract-full').style.display = 'inline'; document.getElementById('2111.12036v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.12036v1-abstract-full" style="display: none;"> The observation of genuine quantum effects in systems governed by non-Hermitian Hamiltonians has been an outstanding challenge in the field. Here we simulate the evolution under such Hamiltonians in the quantum regime on a superconducting quantum processor by using a dilation procedure involving an ancillary qubit. We observe the parity-time ($\mathcal{PT}$)-symmetry breaking phase transition at the exceptional points, obtain the critical exponent, and show that this transition is associated with a loss of state distinguishability. In a two-qubit setting, we show that the entanglement can be modified by local operations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.12036v1-abstract-full').style.display = 'none'; document.getElementById('2111.12036v1-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 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">Journal ref:</span> Communications Physics, 4, 26 (2021) </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/2109.13581">arXiv:2109.13581</a> <span> [<a href="https://arxiv.org/pdf/2109.13581">pdf</a>, <a href="https://arxiv.org/ps/2109.13581">ps</a>, <a href="https://arxiv.org/format/2109.13581">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> <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/10.1063/5.0065224">10.1063/5.0065224 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Protocol for temperature sensing using a three-level transmon circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Sultanov%2C+A">Aidar Sultanov</a>, <a href="/search/?searchtype=author&query=Kuzmanovi%C4%87%2C+M">Marko Kuzmanovi膰</a>, <a href="/search/?searchtype=author&query=Lebedev%2C+A+V">Andrey V. Lebedev</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2109.13581v2-abstract-short" style="display: inline;"> We present a method for in situ temperature measurement of superconducting quantum circuits, by using the first three levels of a transmon device to which we apply a sequence of $蟺$ gates. Our approach employs projective dispersive readout and utilizes the basic properties of the density matrix associated with thermal states. This method works with an averaging readout scheme and does not require… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.13581v2-abstract-full').style.display = 'inline'; document.getElementById('2109.13581v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.13581v2-abstract-full" style="display: none;"> We present a method for in situ temperature measurement of superconducting quantum circuits, by using the first three levels of a transmon device to which we apply a sequence of $蟺$ gates. Our approach employs projective dispersive readout and utilizes the basic properties of the density matrix associated with thermal states. This method works with an averaging readout scheme and does not require a single-shot readout setup. We validate this protocol by performing thermometry in the range of 50 mK - 200 mK, corresponding to a range of residual populations $1\%-20 \%$ for the first excited state and $0.02\%-3 \%$ for the second excited state. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.13581v2-abstract-full').style.display = 'none'; document.getElementById('2109.13581v2-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">10 pages, 9 figures, 1 table</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, 144002 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.00973">arXiv:2109.00973</a> <span> [<a href="https://arxiv.org/pdf/2109.00973">pdf</a>, <a href="https://arxiv.org/ps/2109.00973">ps</a>, <a href="https://arxiv.org/format/2109.00973">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 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/10.1088/1367-2630/ac2393">10.1088/1367-2630/ac2393 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Reinforcement learning-enhanced protocols for coherent population-transfer in three-level quantum systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Brown%2C+J">Jonathon Brown</a>, <a href="/search/?searchtype=author&query=Sgroi%2C+S">Sofia Sgroi</a>, <a href="/search/?searchtype=author&query=Giannelli%2C+L">Luigi Giannelli</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">Elisabetta Paladino</a>, <a href="/search/?searchtype=author&query=Falci%2C+G">Giuseppe Falci</a>, <a href="/search/?searchtype=author&query=Paternostro%2C+M">Mauro Paternostro</a>, <a href="/search/?searchtype=author&query=Ferraro%2C+A">Alessandro Ferraro</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="2109.00973v1-abstract-short" style="display: inline;"> We deploy a combination of reinforcement learning-based approaches and more traditional optimization techniques to identify optimal protocols for population transfer in a multi-level system. We constraint our strategy to the case of fixed coupling rates but time-varying detunings, a situation that would simplify considerably the implementation of population transfer in relevant experimental plat… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.00973v1-abstract-full').style.display = 'inline'; document.getElementById('2109.00973v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.00973v1-abstract-full" style="display: none;"> We deploy a combination of reinforcement learning-based approaches and more traditional optimization techniques to identify optimal protocols for population transfer in a multi-level system. We constraint our strategy to the case of fixed coupling rates but time-varying detunings, a situation that would simplify considerably the implementation of population transfer in relevant experimental platforms, such as semiconducting and superconducting ones. Our approach is able to explore the space of possible control protocols to reveal the existence of efficient protocols that, remarkably, differ from (and can be superior to) standard Raman, STIRAP or other adiabatic schemes. The new protocols that we identify are robust against both energy losses and dephasing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.00973v1-abstract-full').style.display = 'none'; document.getElementById('2109.00973v1-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> 2 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.06978">arXiv:2108.06978</a> <span> [<a href="https://arxiv.org/pdf/2108.06978">pdf</a>, <a href="https://arxiv.org/format/2108.06978">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Disordered Systems and Neural Networks">cond-mat.dis-nn</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/10.1140/epjqt/s40507-021-00105-y">10.1140/epjqt/s40507-021-00105-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Benchmarking Machine Learning Algorithms for Adaptive Quantum Phase Estimation with Noisy Intermediate-Scale Quantum Sensors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Costa%2C+N+F">Nelson Filipe Costa</a>, <a href="/search/?searchtype=author&query=Omar%2C+Y">Yasser Omar</a>, <a href="/search/?searchtype=author&query=Sultanov%2C+A">Aidar Sultanov</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2108.06978v2-abstract-short" style="display: inline;"> Quantum phase estimation is a paradigmatic problem in quantum sensing andmetrology. Here we show that adaptive methods based on classical machinelearning algorithms can be used to enhance the precision of quantum phase estimation when noisy non-entangled qubits are used as sensors. We employ the Differential Evolution (DE) and Particle Swarm Optimization (PSO) algorithms to this task and we identi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.06978v2-abstract-full').style.display = 'inline'; document.getElementById('2108.06978v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.06978v2-abstract-full" style="display: none;"> Quantum phase estimation is a paradigmatic problem in quantum sensing andmetrology. Here we show that adaptive methods based on classical machinelearning algorithms can be used to enhance the precision of quantum phase estimation when noisy non-entangled qubits are used as sensors. We employ the Differential Evolution (DE) and Particle Swarm Optimization (PSO) algorithms to this task and we identify the optimal feedback policies which minimize the Holevo variance. We benchmark these schemes with respect to scenarios that include Gaussian and Random Telegraph fluctuations as well as reduced Ramsey-fringe visibility due to decoherence. We discuss their robustness against noise in connection with real experimental setups such as Mach-Zehnder interferometry with optical photons and Ramsey interferometry in trapped ions,superconducting qubits and nitrogen-vacancy (NV) centers in diamond. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.06978v2-abstract-full').style.display = 'none'; document.getElementById('2108.06978v2-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> 17 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> EPJ Quantum Technol. 8, 16 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2107.04503">arXiv:2107.04503</a> <span> [<a href="https://arxiv.org/pdf/2107.04503">pdf</a>, <a href="https://arxiv.org/format/2107.04503">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> <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/10.1038/s41534-023-00690-z">10.1038/s41534-023-00690-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Critical parametric quantum sensing </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Di+Candia%2C+R">R. Di Candia</a>, <a href="/search/?searchtype=author&query=Minganti%2C+F">F. Minganti</a>, <a href="/search/?searchtype=author&query=Petrovnin%2C+K+V">K. V. Petrovnin</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Felicetti%2C+S">S. Felicetti</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="2107.04503v3-abstract-short" style="display: inline;"> Critical quantum systems are a promising resource for quantum metrology applications, due to the diverging susceptibility developed in proximity of phase transitions. Here, we assess the metrological power of parametric Kerr resonators undergoing driven-dissipative phase transitions. We fully characterize the quantum Fisher information for frequency estimation, and the Helstrom bound for frequency… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.04503v3-abstract-full').style.display = 'inline'; document.getElementById('2107.04503v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2107.04503v3-abstract-full" style="display: none;"> Critical quantum systems are a promising resource for quantum metrology applications, due to the diverging susceptibility developed in proximity of phase transitions. Here, we assess the metrological power of parametric Kerr resonators undergoing driven-dissipative phase transitions. We fully characterize the quantum Fisher information for frequency estimation, and the Helstrom bound for frequency discrimination. By going beyond the asymptotic regime, we show that the Heisenberg precision can be achieved with experimentally reachable parameters. We design protocols that exploit the critical behavior of nonlinear resonators to enhance the precision of quantum magnetometers and the fidelity of superconducting qubit readout. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2107.04503v3-abstract-full').style.display = 'none'; document.getElementById('2107.04503v3-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 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 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">13 pages + Supplemental Material</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 9, 23 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.01394">arXiv:2102.01394</a> <span> [<a href="https://arxiv.org/pdf/2102.01394">pdf</a>, <a href="https://arxiv.org/format/2102.01394">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="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/10.1088/1367-2630/abe1e6">10.1088/1367-2630/abe1e6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Klein tunneling through the trapezoidal potential barrier in graphene: conductance and shot noise </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="2102.01394v2-abstract-short" style="display: inline;"> When a single-layer graphene sheet is contacted with metallic electrodes, tunnel barriers are formed as a result of the doping of graphene by the metal in the contact region. If the Fermi energy level is modulated by a gate voltage, the phenomenon of Klein tunneling results in specific features in the conductance and noise. Here we obtain analytically exact solutions for the transmission and refle… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.01394v2-abstract-full').style.display = 'inline'; document.getElementById('2102.01394v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.01394v2-abstract-full" style="display: none;"> When a single-layer graphene sheet is contacted with metallic electrodes, tunnel barriers are formed as a result of the doping of graphene by the metal in the contact region. If the Fermi energy level is modulated by a gate voltage, the phenomenon of Klein tunneling results in specific features in the conductance and noise. Here we obtain analytically exact solutions for the transmission and reflection probability amplitudes using a trapezoidal potential barrier, allowing us to calculate the differential conductance and the Fano factor for a graphene sheet in the ballistic regime. We put in evidence an unexpected global symmetry - the transmission probability is the same for energies symmetric with respect to half of the barrier height. We outline a proposal for the experimental verification of these ideas using realistic sample parameters. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.01394v2-abstract-full').style.display = 'none'; document.getElementById('2102.01394v2-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, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">18 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> New J. Phys. 23, 043027 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2010.06611">arXiv:2010.06611</a> <span> [<a href="https://arxiv.org/pdf/2010.06611">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> <span class="tag is-small is-grey 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="History and Philosophy of Physics">physics.hist-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/10.1051/epn/2020402">10.1051/epn/2020402 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Listening to the quantum vacuum: a perspective on the dynamical Casimir effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Johansson%2C+G">G枚ran Johansson</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="2010.06611v1-abstract-short" style="display: inline;"> Modern quantum field theory has offered us a very intriguing picture of empty space. The vacuum state is no longer an inert, motionless state. We are instead dealing with an entity teeming with fluctuations that continuously produce virtual particles popping in and out of existence. The dynamical Casimir effect is a paradigmatic phenomenon, whereby these particles are converted into real particles… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.06611v1-abstract-full').style.display = 'inline'; document.getElementById('2010.06611v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2010.06611v1-abstract-full" style="display: none;"> Modern quantum field theory has offered us a very intriguing picture of empty space. The vacuum state is no longer an inert, motionless state. We are instead dealing with an entity teeming with fluctuations that continuously produce virtual particles popping in and out of existence. The dynamical Casimir effect is a paradigmatic phenomenon, whereby these particles are converted into real particles (photons) by changing the boundary conditions of the field. It was predicted 50 years ago by Gerald T. Moore and it took more than 40 years until the first experimental verification. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2010.06611v1-abstract-full').style.display = 'none'; document.getElementById('2010.06611v1-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 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">6 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Europhysics News 51/4 (2020), pp. 18-20 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.10038">arXiv:2009.10038</a> <span> [<a href="https://arxiv.org/pdf/2009.10038">pdf</a>, <a href="https://arxiv.org/format/2009.10038">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 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/10.1088/1367-2630/abe9d7">10.1088/1367-2630/abe9d7 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Finite-time quantum Stirling heat engine </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Raja%2C+S+H">Sina Hamedani Raja</a>, <a href="/search/?searchtype=author&query=Maniscalco%2C+S">Sabrina Maniscalco</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G">Gheorghe-Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Pekola%2C+J+P">Jukka P. Pekola</a>, <a href="/search/?searchtype=author&query=Gullo%2C+N+L">Nicolino Lo Gullo</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="2009.10038v1-abstract-short" style="display: inline;"> We study the thermodynamic performance of the finite-time non-regenerative Stirling cycle used as a quantum heat engine. We consider specifically the case in which the working substance (WS) is a two-level system. The Stirling cycle is made of two isochoric transformations separated by a compression and an expansion stroke during which the working substance is in contact with a thermal reservoir.… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.10038v1-abstract-full').style.display = 'inline'; document.getElementById('2009.10038v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.10038v1-abstract-full" style="display: none;"> We study the thermodynamic performance of the finite-time non-regenerative Stirling cycle used as a quantum heat engine. We consider specifically the case in which the working substance (WS) is a two-level system. The Stirling cycle is made of two isochoric transformations separated by a compression and an expansion stroke during which the working substance is in contact with a thermal reservoir. To describe these two strokes we derive a non-Markovian master equation which allows to study the dynamics of a driven open quantum system with arbitrary fast driving. We found that the finite-time dynamics and thermodynamics of the cycle depend non-trivially on the different time scales at play. In particular, driving the WS at a time scale comparable to the resonance time of the bath enhances the performance of the cycle and allows for an efficiency higher than the efficiency of the slow adiabatic cycle, but still below the Carnot bound. Interestingly, performance of the cycle is dependent on the compression and expansion speeds asymmetrically. This suggests new freedom in optimizing quantum heat engines. We further show that the maximum output power and the maximum efficiency can be achieved almost simultaneously, although the net extractable work declines by speeding up the drive. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.10038v1-abstract-full').style.display = 'none'; document.getElementById('2009.10038v1-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 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">Journal ref:</span> New J. Phys 23, 033034 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2005.06229">arXiv:2005.06229</a> <span> [<a href="https://arxiv.org/pdf/2005.06229">pdf</a>, <a href="https://arxiv.org/format/2005.06229">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 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/10.1002/andp.202100038">10.1002/andp.202100038 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bath-induced collective phenomena on superconducting qubits: synchronization, subradiance, and entanglement generation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Cattaneo%2C+M">Marco Cattaneo</a>, <a href="/search/?searchtype=author&query=Giorgi%2C+G+L">Gian Luca Giorgi</a>, <a href="/search/?searchtype=author&query=Maniscalco%2C+S">Sabrina Maniscalco</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Zambrini%2C+R">Roberta Zambrini</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="2005.06229v3-abstract-short" style="display: inline;"> A common environment acting on a pair of qubits gives rise to a plethora of different phenomena, such as the generation of qubit-qubit entanglement, quantum synchronization and subradiance. Here we define time-independent figures of merit for entanglement generation, quantum synchronization and subradiance, and perform an extensive analytical and numerical study of their dependence on model parame… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.06229v3-abstract-full').style.display = 'inline'; document.getElementById('2005.06229v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2005.06229v3-abstract-full" style="display: none;"> A common environment acting on a pair of qubits gives rise to a plethora of different phenomena, such as the generation of qubit-qubit entanglement, quantum synchronization and subradiance. Here we define time-independent figures of merit for entanglement generation, quantum synchronization and subradiance, and perform an extensive analytical and numerical study of their dependence on model parameters. We also address a recently proposed measure of the collectiveness of the dynamics driven by the bath, and find that it almost perfectly witnesses the behavior of entanglement generation. Our results show that synchronization and subradiance can be employed as reliable local signatures of an entangling common-bath in a general scenario. Finally, we propose an experimental implementation of the model based on two transmon qubits capacitively coupled to a common resistor, which provides a versatile quantum simulation platform of the open system in any regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2005.06229v3-abstract-full').style.display = 'none'; document.getElementById('2005.06229v3-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 May, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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 version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Annalen der Physik 533, 2100038 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2004.07192">arXiv:2004.07192</a> <span> [<a href="https://arxiv.org/pdf/2004.07192">pdf</a>, <a href="https://arxiv.org/format/2004.07192">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> <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/10.1103/PRXQuantum.2.020316">10.1103/PRXQuantum.2.020316 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Two-way covert quantum communication in the microwave regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Di+Candia%2C+R">R. Di Candia</a>, <a href="/search/?searchtype=author&query=Yi%C4%9Fitler%2C+H">H. Yi臒itler</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=J%C3%A4ntti%2C+R">R. J盲ntti</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="2004.07192v2-abstract-short" style="display: inline;"> Quantum communication addresses the problem of exchanging information across macroscopic distances by employing encryption techniques based on quantum mechanical laws. Here, we advance a new paradigm for secure quantum communication by combining backscattering concepts with covert communication in the microwave regime. Our protocol allows communication between Alice, who uses only discrete phase m… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.07192v2-abstract-full').style.display = 'inline'; document.getElementById('2004.07192v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2004.07192v2-abstract-full" style="display: none;"> Quantum communication addresses the problem of exchanging information across macroscopic distances by employing encryption techniques based on quantum mechanical laws. Here, we advance a new paradigm for secure quantum communication by combining backscattering concepts with covert communication in the microwave regime. Our protocol allows communication between Alice, who uses only discrete phase modulations, and Bob, who has access to cryogenic microwave technology. Using notions of quantum channel discrimination and quantum metrology, we find the ultimate bounds for the receiver performance, proving that quantum correlations can enhance the SNR by up to $6$ dB. These bounds rule out any quantum illumination advantage when the source is strongly amplified, and show that a relevant gain is possible only in the low photon-number regime. We show how the protocol can be used for covert communication, where the carrier signal is indistinguishable from the thermal noise in the environment. We complement our information-theoretic results with a feasible experimental proposal in a circuit-QED platform. This work makes a decisive step toward implementing secure quantum communication concepts in the previously uncharted $1$-$10$ GHz frequency range, in the scenario when the disposable power of one party is severely constrained. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2004.07192v2-abstract-full').style.display = 'none'; document.getElementById('2004.07192v2-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 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 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">26 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> PRX Quantum 2, 020316 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.12770">arXiv:2003.12770</a> <span> [<a href="https://arxiv.org/pdf/2003.12770">pdf</a>, <a href="https://arxiv.org/format/2003.12770">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 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/10.1002/andp.202200082">10.1002/andp.202200082 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Large-scale quantum hybrid solution for linear systems of equations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Perelshtein%2C+M+R">M. R. Perelshtein</a>, <a href="/search/?searchtype=author&query=Pakhomchik%2C+A+I">A. I. Pakhomchik</a>, <a href="/search/?searchtype=author&query=Melnikov%2C+A+A">A. A. Melnikov</a>, <a href="/search/?searchtype=author&query=Novikov%2C+A+A">A. A. Novikov</a>, <a href="/search/?searchtype=author&query=Glatz%2C+A">A. Glatz</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Vinokur%2C+V+M">V. M. Vinokur</a>, <a href="/search/?searchtype=author&query=Lesovik%2C+G+B">G. B. Lesovik</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="2003.12770v3-abstract-short" style="display: inline;"> State-of-the-art noisy intermediate-scale quantum devices (NISQ), although imperfect, enable computational tasks that are manifestly beyond the capabilities of modern classical supercomputers. However, present quantum computations are restricted to exploring specific simplified protocols, whereas the implementation of full-scale quantum algorithms aimed at solving concrete large scale problems ari… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.12770v3-abstract-full').style.display = 'inline'; document.getElementById('2003.12770v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.12770v3-abstract-full" style="display: none;"> State-of-the-art noisy intermediate-scale quantum devices (NISQ), although imperfect, enable computational tasks that are manifestly beyond the capabilities of modern classical supercomputers. However, present quantum computations are restricted to exploring specific simplified protocols, whereas the implementation of full-scale quantum algorithms aimed at solving concrete large scale problems arising in data analysis and numerical modelling remains a challenge. Here we introduce and implement a hybrid quantum algorithm for solving linear systems of equations with exponential speedup, utilizing quantum phase estimation, one of the exemplary core protocols for quantum computing. We introduce theoretically classes of linear systems that are suitable for current generation quantum machines and solve experimentally a $2^{17}$-dimensional problem on superconducting IBMQ devices, a record for linear system solution on quantum computers. The considered large-scale algorithm shows superiority over conventional solutions, demonstrates advantages of quantum data processing via phase estimation and holds high promise for meeting practically relevant challenges. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.12770v3-abstract-full').style.display = 'none'; document.getElementById('2003.12770v3-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 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 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">8 pages, 6 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/2003.09939">arXiv:2003.09939</a> <span> [<a href="https://arxiv.org/pdf/2003.09939">pdf</a>, <a href="https://arxiv.org/format/2003.09939">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 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/PhysRevResearch.2.043079">10.1103/PhysRevResearch.2.043079 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Majorana representation of adiabatic and superadiabatic processes in three-level systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Dogra%2C+S">Shruti Dogra</a>, <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="2003.09939v2-abstract-short" style="display: inline;"> We show that stimulated Raman adiabatic passage (STIRAP) and its superadiabatic version (saSTIRAP) have a natural geometric two-star representation on the Majorana sphere. In the case of STIRAP, we find that the evolution is confined to a vertical plane. A faster evolution can be achieved in the saSTIRAP protocol, which employs a counterdiabatic Hamiltonian to nullify the non-adiabatic excitations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.09939v2-abstract-full').style.display = 'inline'; document.getElementById('2003.09939v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.09939v2-abstract-full" style="display: none;"> We show that stimulated Raman adiabatic passage (STIRAP) and its superadiabatic version (saSTIRAP) have a natural geometric two-star representation on the Majorana sphere. In the case of STIRAP, we find that the evolution is confined to a vertical plane. A faster evolution can be achieved in the saSTIRAP protocol, which employs a counterdiabatic Hamiltonian to nullify the non-adiabatic excitations. We derive this Hamiltonian in the Majorana picture, and we observe how, under realistic experimental parameters, the counterdiabatic term corrects the trajectory of the Majorana stars toward the dark state. We also introduce a spin-1 average vector and present its evolution during the two processes, demonstrating that it provides a measure of nonadiabaticity. We show that the Majorana representation can be used as a sensitive tool for the detection of process errors due to ac Stark shifts and non-adiabatic transitions. Finally, we provide an extension of these results to mixed states and processes with decoherence. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.09939v2-abstract-full').style.display = 'none'; document.getElementById('2003.09939v2-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 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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">Comments are welcome</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 2, 043079 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1912.11087">arXiv:1912.11087</a> <span> [<a href="https://arxiv.org/pdf/1912.11087">pdf</a>, <a href="https://arxiv.org/format/1912.11087">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 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/PhysRevA.103.023707">10.1103/PhysRevA.103.023707 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> General solution of the time evolution of two interacting harmonic oscillators </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bruschi%2C+D+E">David Edward Bruschi</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Fuentes%2C+I">Ivette Fuentes</a>, <a href="/search/?searchtype=author&query=Wilhelm%2C+F+K">Frank K. Wilhelm</a>, <a href="/search/?searchtype=author&query=Schell%2C+A+W">Andreas W. Schell</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="1912.11087v3-abstract-short" style="display: inline;"> We study the time evolution of an ideal system composed of two harmonic oscillators coupled through a quadratic Hamiltonian with arbitrary interaction strength. We solve its dynamics analytically by employing tools from symplectic geometry. In particular, we use this result to completely characterize the dynamics of the two oscillators interacting in the ultrastrong coupling regime with additional… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.11087v3-abstract-full').style.display = 'inline'; document.getElementById('1912.11087v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1912.11087v3-abstract-full" style="display: none;"> We study the time evolution of an ideal system composed of two harmonic oscillators coupled through a quadratic Hamiltonian with arbitrary interaction strength. We solve its dynamics analytically by employing tools from symplectic geometry. In particular, we use this result to completely characterize the dynamics of the two oscillators interacting in the ultrastrong coupling regime with additional single-mode squeezing on both oscillators, as well as higher order terms. Furthermore, we compute quantities of interest, such as the average number of excitations and the correlations that are established between the two subsystems due to the evolution. We find that this model predicts a second order phase transition and we compute the critical exponents and the critical value. We also provide an exact decoupling of the time evolution in terms of simple quantum optical operations, which can be used for practical implementations and studies. Finally, we show how our techniques can be extended to include more oscillators and higher order interactions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1912.11087v3-abstract-full').style.display = 'none'; document.getElementById('1912.11087v3-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> 12 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 December, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 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">16 pages, 3 figures. I. Fuentes previously published as I. Fuentes-Schuller and I. Fuentes-Guridi</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 103, 023707 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.06796">arXiv:1911.06796</a> <span> [<a href="https://arxiv.org/pdf/1911.06796">pdf</a>, <a href="https://arxiv.org/format/1911.06796">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> <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/10.1126/sciadv.aau5999">10.1126/sciadv.aau5999 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Superadiabatic population transfer in a three-level superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">Sergey Danilin</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="1911.06796v1-abstract-short" style="display: inline;"> Adiabatic manipulation of the quantum state is an essential tool in modern quantum information processing. Here we demonstrate the speed-up of the adiabatic population transfer in a three-level superconducting transmon circuit by suppressing the spurious non-adiabatic excitations with an additional two-photon microwave pulse. We apply this superadiabatic method to the stimulated Raman adiabatic pa… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.06796v1-abstract-full').style.display = 'inline'; document.getElementById('1911.06796v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.06796v1-abstract-full" style="display: none;"> Adiabatic manipulation of the quantum state is an essential tool in modern quantum information processing. Here we demonstrate the speed-up of the adiabatic population transfer in a three-level superconducting transmon circuit by suppressing the spurious non-adiabatic excitations with an additional two-photon microwave pulse. We apply this superadiabatic method to the stimulated Raman adiabatic passage, realizing fast and robust population transfer from the ground state to the second excited state of the quantum circuit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.06796v1-abstract-full').style.display = 'none'; document.getElementById('1911.06796v1-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 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">35 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science advances 5, eaau5999 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.01611">arXiv:1908.01611</a> <span> [<a href="https://arxiv.org/pdf/1908.01611">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Atomic Physics">physics.atom-ph</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-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/10.1088/1361-6455/ab3995">10.1088/1361-6455/ab3995 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Roadmap on STIRAP applications </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bergmann%2C+K">Klaas Bergmann</a>, <a href="/search/?searchtype=author&query=N%C3%A4gerl%2C+H">Hanns-Christoph N盲gerl</a>, <a href="/search/?searchtype=author&query=Panda%2C+C">Cristian Panda</a>, <a href="/search/?searchtype=author&query=Gabrielse%2C+G">Gerald Gabrielse</a>, <a href="/search/?searchtype=author&query=Miloglyadov%2C+E">Eduard Miloglyadov</a>, <a href="/search/?searchtype=author&query=Quack%2C+M">Martin Quack</a>, <a href="/search/?searchtype=author&query=Seyfang%2C+G">Georg Seyfang</a>, <a href="/search/?searchtype=author&query=Wichmann%2C+G">Gunther Wichmann</a>, <a href="/search/?searchtype=author&query=Ospelkaus%2C+S">Silke Ospelkaus</a>, <a href="/search/?searchtype=author&query=Kuhn%2C+A">Axel Kuhn</a>, <a href="/search/?searchtype=author&query=Longhi%2C+S">Stefano Longhi</a>, <a href="/search/?searchtype=author&query=Szameit%2C+A">Alexander Szameit</a>, <a href="/search/?searchtype=author&query=Pirro%2C+P">Philipp Pirro</a>, <a href="/search/?searchtype=author&query=Hillebrands%2C+B">Burkard Hillebrands</a>, <a href="/search/?searchtype=author&query=Zhu%2C+X">Xue-Feng Zhu</a>, <a href="/search/?searchtype=author&query=Zhu%2C+J">Jie Zhu</a>, <a href="/search/?searchtype=author&query=Drewsen%2C+M">Michael Drewsen</a>, <a href="/search/?searchtype=author&query=Hensinger%2C+W+K">Winfried K. Hensinger</a>, <a href="/search/?searchtype=author&query=Weidt%2C+S">Sebastian Weidt</a>, <a href="/search/?searchtype=author&query=Halfmann%2C+T">Thomas Halfmann</a>, <a href="/search/?searchtype=author&query=Wang%2C+H">Hailin Wang</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Vitanov%2C+N+V">Nikolay V. Vitanov</a>, <a href="/search/?searchtype=author&query=Mompart%2C+J">J. Mompart</a>, <a href="/search/?searchtype=author&query=Busch%2C+T">Th. Busch</a> , et al. (9 additional authors not shown) </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="1908.01611v1-abstract-short" style="display: inline;"> STIRAP (Stimulated Raman Adiabatic Passage) is a powerful laser-based method, usually involving two photons, for efficient and selective transfer of population between quantum states. A particularly interesting feature is the fact that the coupling between the initial and the final quantum states is via an intermediate state even though the lifetime of the latter can be much shorter than the inter… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.01611v1-abstract-full').style.display = 'inline'; document.getElementById('1908.01611v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.01611v1-abstract-full" style="display: none;"> STIRAP (Stimulated Raman Adiabatic Passage) is a powerful laser-based method, usually involving two photons, for efficient and selective transfer of population between quantum states. A particularly interesting feature is the fact that the coupling between the initial and the final quantum states is via an intermediate state even though the lifetime of the latter can be much shorter than the interaction time with the laser radiation. Nevertheless, spontaneous emission from the intermediate state is prevented by quantum interference. Maintaining the coherence between the initial and final state throughout the transfer process is crucial. STIRAP was initially developed with applications in chemical dynamics in mind. That is why the original paper of 1990 was published in The Journal of Chemical Physics. However, as of about the year 2000, the unique capabilities of STIRAP and its robustness with respect to small variations of some experimental parameters stimulated many researchers to apply the scheme in a variety of other fields of physics. The successes of these efforts are documented in this collection of articles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.01611v1-abstract-full').style.display = 'none'; document.getElementById('1908.01611v1-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, 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 for publication in Journal of Physics B: Atomic, Molecular and Optical Physics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Phys. B: At. Mol. Opt. Phys. 52 202001 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.05598">arXiv:1904.05598</a> <span> [<a href="https://arxiv.org/pdf/1904.05598">pdf</a>, <a href="https://arxiv.org/format/1904.05598">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> <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/10.1088/2058-9565/aaa640">10.1088/2058-9565/aaa640 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Optimal superadiabatic population transfer and gates by dynamical phase corrections </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">A. Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1904.05598v1-abstract-short" style="display: inline;"> In many quantum technologies adiabatic processes are used for coherent quantum state operations, offering inherent robustness to errors in the control parameters. The main limitation is the long operation time resulting from the requirement of adiabaticity. The superadiabatic method allows for faster operation, by applying counterdiabatic driving that corrects for excitations resulting from the vi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.05598v1-abstract-full').style.display = 'inline'; document.getElementById('1904.05598v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.05598v1-abstract-full" style="display: none;"> In many quantum technologies adiabatic processes are used for coherent quantum state operations, offering inherent robustness to errors in the control parameters. The main limitation is the long operation time resulting from the requirement of adiabaticity. The superadiabatic method allows for faster operation, by applying counterdiabatic driving that corrects for excitations resulting from the violation of the adiabatic condition. In this article we show how to construct the counterdiabatic Hamiltonian in a system with forbidden transitions by using two-photon processes and how to correct for the resulting time-dependent ac-Stark shifts in order to enable population transfer with unit fidelity. We further demonstrate that superadiabatic stimulated Raman passage can realize a robust unitary NOT-gate between the ground state and the second excited state of a three-level system. The results can be readily applied to a three-level transmon with the ladder energy level structure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.05598v1-abstract-full').style.display = 'none'; document.getElementById('1904.05598v1-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 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">26 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Sci. Technol. 3, 024006 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.05854">arXiv:1902.05854</a> <span> [<a href="https://arxiv.org/pdf/1902.05854">pdf</a>, <a href="https://arxiv.org/format/1902.05854">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 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/10.3390/e20080606">10.3390/e20080606 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-Local Parity Measurements and the Quantum Pigeonhole Effect </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1902.05854v1-abstract-short" style="display: inline;"> The pigeonhole principle upholds the idea that by ascribing to three different particles either one of two properties, we necessarily end up in a situation when at least two of the particles have the same property. In quantum physics, this principle is violated in experiments involving postselection of the particles in appropriately-chosen states. Here, we give two explicit constructions using sta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.05854v1-abstract-full').style.display = 'inline'; document.getElementById('1902.05854v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.05854v1-abstract-full" style="display: none;"> The pigeonhole principle upholds the idea that by ascribing to three different particles either one of two properties, we necessarily end up in a situation when at least two of the particles have the same property. In quantum physics, this principle is violated in experiments involving postselection of the particles in appropriately-chosen states. Here, we give two explicit constructions using standard gates and measurements that illustrate this fact. Intriguingly, the procedures described are manifestly non-local, which demonstrates that the correlations needed to observe the violation of this principle can be created without direct interactions between particles. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.05854v1-abstract-full').style.display = 'none'; document.getElementById('1902.05854v1-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">5 pages, 2 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Entropy 20, 606 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1901.05655">arXiv:1901.05655</a> <span> [<a href="https://arxiv.org/pdf/1901.05655">pdf</a>, <a href="https://arxiv.org/format/1901.05655">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="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/10.1103/PhysRevA.99.063828">10.1103/PhysRevA.99.063828 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Photon blockade and the quantum-to-classical transition in the driven-dissipative Josephson pendulum coupled to a resonator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Pietik%C3%A4inen%2C+I">I. Pietik盲inen</a>, <a href="/search/?searchtype=author&query=Tuorila%2C+J">J. Tuorila</a>, <a href="/search/?searchtype=author&query=Golubev%2C+D+S">D. S. Golubev</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1901.05655v2-abstract-short" style="display: inline;"> We investigate the driven quantum phase transition between the oscillating motion and the classical nearly free rotations of the Josephson pendulum coupled to a harmonic oscillator in the presence of dissipation. We refer to this as the Josephson-Rabi model. This model describes the standard setup of circuit quantum electrodynamics, where typically a transmon device is embedded in a superconductin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.05655v2-abstract-full').style.display = 'inline'; document.getElementById('1901.05655v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1901.05655v2-abstract-full" style="display: none;"> We investigate the driven quantum phase transition between the oscillating motion and the classical nearly free rotations of the Josephson pendulum coupled to a harmonic oscillator in the presence of dissipation. We refer to this as the Josephson-Rabi model. This model describes the standard setup of circuit quantum electrodynamics, where typically a transmon device is embedded in a superconducting cavity. We find that by treating the system quantum mechanically this transition occurs at higher drive powers than expected from an all-classical treatment, which is a consequence of the quasiperiodicity originating in the discrete energy spectrum of the bound states. We calculate the photon number in the resonator and show that its dependence on the drive power is nonlinear. In addition, the resulting multi-photon blockade phenomenon is sensitive to the truncation of the number of states in the transmon, which limits the applicability of the standard Jaynes-Cummings model as an approximation for the pendulum-oscillator system. We calculate the nth order correlation functions of the blockaded microwave photons and observe the differences between the rotating-wave approximation and the full multilevel Josephson-Rabi Hamiltonian with the counter-rotating terms included. Finally, we compare two different approaches to dissipation, namely the Floquet-Born-Markov and the Lindblad formalisms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1901.05655v2-abstract-full').style.display = 'none'; document.getElementById('1901.05655v2-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 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 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">18 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 99, 063828 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.02396">arXiv:1809.02396</a> <span> [<a href="https://arxiv.org/pdf/1809.02396">pdf</a>, <a href="https://arxiv.org/format/1809.02396">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="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/10.1103/PhysRevLett.121.243601">10.1103/PhysRevLett.121.243601 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Revealing hidden quantum correlations in an electromechanical measurement </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Ockeloen-Korppi%2C+C+F">C. F. Ockeloen-Korppi</a>, <a href="/search/?searchtype=author&query=Damsk%C3%A4gg%2C+E">E. Damsk盲gg</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Massel%2C+F">F. Massel</a>, <a href="/search/?searchtype=author&query=Sillanp%C3%A4%C3%A4%2C+M+A">M. A. Sillanp盲盲</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="1809.02396v1-abstract-short" style="display: inline;"> Under a strong quantum measurement, the motion of an oscillator is disturbed by the measurement back-action, as required by the Heisenberg uncertainty principle. When a mechanical oscillator is continuously monitored via an electromagnetic cavity, as in a cavity optomechanical measurement, the back-action is manifest by the shot noise of incoming photons that becomes imprinted onto the motion of t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.02396v1-abstract-full').style.display = 'inline'; document.getElementById('1809.02396v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.02396v1-abstract-full" style="display: none;"> Under a strong quantum measurement, the motion of an oscillator is disturbed by the measurement back-action, as required by the Heisenberg uncertainty principle. When a mechanical oscillator is continuously monitored via an electromagnetic cavity, as in a cavity optomechanical measurement, the back-action is manifest by the shot noise of incoming photons that becomes imprinted onto the motion of the oscillator. Following the photons leaving the cavity, the correlations appear as squeezing of quantum noise in the emitted field. Here we observe such "ponderomotive" squeezing in the microwave domain using an electromechanical device made out of a superconducting resonator and a drumhead mechanical oscillator. Under a strong measurement, the emitted field develops complex-valued quantum correlations, which in general are not completely accessible by standard homodyne measurements. We recover these hidden correlations, using a phase-sensitive measurement scheme employing two local oscillators. The utilization of hidden correlations presents a step forward in the detection of weak forces, as it allows to fully utilize the quantum noise reduction under the conditions of strong force sensitivity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.02396v1-abstract-full').style.display = 'none'; document.getElementById('1809.02396v1-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 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">Comments:</span> <span class="has-text-grey-dark mathjax">6 pages, 5 figures and supplementary information</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 121, 243601 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1804.01759">arXiv:1804.01759</a> <span> [<a href="https://arxiv.org/pdf/1804.01759">pdf</a>, <a href="https://arxiv.org/format/1804.01759">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 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/10.1088/1402-4896/aab084">10.1088/1402-4896/aab084 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental state control by fast non-Abelian holonomic gates with a superconducting qutrit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">A. Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1804.01759v1-abstract-short" style="display: inline;"> Quantum state manipulation with gates based on geometric phases acquired during cyclic operations promises inherent fault-tolerance and resilience to local fluctuations in the control parameters. Here we create a general non-Abelian and non-adiabatic holonomic gate acting in the $(\ket{0},\ket{2})$ subspace of a three-level transmon fabricated in a fully coplanar design. Experimentally, this is re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.01759v1-abstract-full').style.display = 'inline'; document.getElementById('1804.01759v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1804.01759v1-abstract-full" style="display: none;"> Quantum state manipulation with gates based on geometric phases acquired during cyclic operations promises inherent fault-tolerance and resilience to local fluctuations in the control parameters. Here we create a general non-Abelian and non-adiabatic holonomic gate acting in the $(\ket{0},\ket{2})$ subspace of a three-level transmon fabricated in a fully coplanar design. Experimentally, this is realized by simultaneously coupling the first two transitions by microwave pulses with amplitudes and phases defined such that the condition of parallel transport is fulfilled. We demonstrate the creation of arbitrary superpositions in this subspace by changing the amplitudes of the pulses and the relative phase between them. We use two-photon pulses acting in the holonomic subspace to reveal the coherence of the state created by the geometric gate pulses and to prepare different superposition states. We also test the action of holonomic NOT and Hadamard gates on superpositions in the $(\ket{0},\ket{2})$ subspace. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1804.01759v1-abstract-full').style.display = 'none'; document.getElementById('1804.01759v1-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 April, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Scr. 93 (2018) 055101 (9pp) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1801.02230">arXiv:1801.02230</a> <span> [<a href="https://arxiv.org/pdf/1801.02230">pdf</a>, <a href="https://arxiv.org/format/1801.02230">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> <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/s41534-018-0078-y">10.1038/s41534-018-0078-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum-enhanced magnetometry by phase estimation algorithms with a single artificial atom </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Lebedev%2C+A+V">A. V. Lebedev</a>, <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">A. Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Lesovik%2C+G+B">G. B. Lesovik</a>, <a href="/search/?searchtype=author&query=Blatter%2C+G">G. Blatter</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1801.02230v2-abstract-short" style="display: inline;"> Phase estimation algorithms are key protocols in quantum information processing. Besides applications in quantum computing, they can also be employed in metrology as they allow for fast extraction of information stored in the quantum state of a system. Here, we implement two suitably modified phase estimation procedures, the Kitaev- and the semiclassical Fourier-transform algorithms, using an arti… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.02230v2-abstract-full').style.display = 'inline'; document.getElementById('1801.02230v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1801.02230v2-abstract-full" style="display: none;"> Phase estimation algorithms are key protocols in quantum information processing. Besides applications in quantum computing, they can also be employed in metrology as they allow for fast extraction of information stored in the quantum state of a system. Here, we implement two suitably modified phase estimation procedures, the Kitaev- and the semiclassical Fourier-transform algorithms, using an artificial atom realized with a superconducting transmon circuit. We demonstrate that both algorithms yield a flux sensitivity exceeding the classical shot-noise limit of the device, allowing one to approach the Heisenberg limit. Our experiment paves the way for the use of superconducting qubits as metrological devices which are potentially able to outperform the best existing flux sensors with a sensitivity enhanced by few orders of magnitude. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1801.02230v2-abstract-full').style.display = 'none'; document.getElementById('1801.02230v2-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 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 January, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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, 4 figures and Supplementary Information</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 4, 29 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.06172">arXiv:1711.06172</a> <span> [<a href="https://arxiv.org/pdf/1711.06172">pdf</a>, <a href="https://arxiv.org/format/1711.06172">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 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/PhysRevA.97.022115">10.1103/PhysRevA.97.022115 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum metrology with a transmon qutrit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Shlyakhov%2C+A+R">A. R. Shlyakhov</a>, <a href="/search/?searchtype=author&query=Zemlyanov%2C+V+V">V. V. Zemlyanov</a>, <a href="/search/?searchtype=author&query=Suslov%2C+M+V">M. V. Suslov</a>, <a href="/search/?searchtype=author&query=Lebedev%2C+A+V">A. V. Lebedev</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Lesovik%2C+G+B">G. B. Lesovik</a>, <a href="/search/?searchtype=author&query=Blatter%2C+G">G. Blatter</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="1711.06172v2-abstract-short" style="display: inline;"> Making use of coherence and entanglement as metrological quantum resources allows to improve the measurement precision from the shot-noise- or quantum limit to the Heisenberg limit. Quantum metrology then relies on the availability of quantum engineered systems that involve controllable quantum degrees of freedom which are sensitive to the measured quantity. Sensors operating in the qubit mode and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.06172v2-abstract-full').style.display = 'inline'; document.getElementById('1711.06172v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.06172v2-abstract-full" style="display: none;"> Making use of coherence and entanglement as metrological quantum resources allows to improve the measurement precision from the shot-noise- or quantum limit to the Heisenberg limit. Quantum metrology then relies on the availability of quantum engineered systems that involve controllable quantum degrees of freedom which are sensitive to the measured quantity. Sensors operating in the qubit mode and exploiting their coherence in a phase-sensitive measurement have been shown to approach the Heisenberg scaling in precision. Here, we show that this result can be further improved by operating the quantum sensor in the qudit mode, i.e., by exploiting $d$ rather than 2 levels. Specifically, we describe the metrological algorithm for using a superconducting transmon device operating in a qutrit mode as a magnetometer. The algorithm is based on the base-3 semi-quantum Fourier transformation and enhances the quantum theoretical performance of the sensor by a factor 2. Even more, the practical gain of our qutrit-implementation is found in a reduction of the number of iteration steps of the quantum Fourier transformation by a factor $\log 2/\log 3 \approx 0.63$ as compared to the qubit mode. We show, that a two-tone capacitively coupled rf-signal is sufficient for the implementation of the algorithm. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.06172v2-abstract-full').style.display = 'none'; document.getElementById('1711.06172v2-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> 2 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 16 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2017. </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, 1 figure</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 97, 022115 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.07454">arXiv:1710.07454</a> <span> [<a href="https://arxiv.org/pdf/1710.07454">pdf</a>, <a href="https://arxiv.org/format/1710.07454">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 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/10.1088/1742-6596/969/1/012141">10.1088/1742-6596/969/1/012141 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Cross-coupling effects in circuit-QED stimulated Raman adiabatic passage </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">A. Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1710.07454v1-abstract-short" style="display: inline;"> Stimulated Raman adiabatic passage is a quantum protocol that can be used for robust state preparation in a three-level system. It has been commonly employed in quantum optics, but recently this technique has drawn attention also in circuit quantum electrodynamics. The protocol relies on two slowly varying drive pulses that couple the initial and the target state via an intermediate state, which r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.07454v1-abstract-full').style.display = 'inline'; document.getElementById('1710.07454v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.07454v1-abstract-full" style="display: none;"> Stimulated Raman adiabatic passage is a quantum protocol that can be used for robust state preparation in a three-level system. It has been commonly employed in quantum optics, but recently this technique has drawn attention also in circuit quantum electrodynamics. The protocol relies on two slowly varying drive pulses that couple the initial and the target state via an intermediate state, which remains unpopulated. Here we study the detrimental effect of the parasitic couplings of the drives into transitions other than those required by the protocol. The effect is most prominent in systems with almost harmonic energy level structure, such as the transmon. We show that under these conditions in the presence of decoherence there exists an optimal STIRAP amplitude for population transfer. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.07454v1-abstract-full').style.display = 'none'; document.getElementById('1710.07454v1-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 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </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">Will be published in proceedings for 28th International Conference for Low Temperature Physics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Journal of Physics: Conference Series, Volume 969 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.00588">arXiv:1710.00588</a> <span> [<a href="https://arxiv.org/pdf/1710.00588">pdf</a>, <a href="https://arxiv.org/format/1710.00588">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="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/10.1007/s10909-018-1857-8">10.1007/s10909-018-1857-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Multilevel effects in a driven generalized Rabi model </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Pietik%C3%A4inen%2C+I">I. Pietik盲inen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Kumar%2C+K+S">K. S. Kumar</a>, <a href="/search/?searchtype=author&query=Tuorila%2C+J">J. Tuorila</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1710.00588v2-abstract-short" style="display: inline;"> We study numerically the onset of higher-level excitations and resonance frequency shifts in the generalized multilevel Rabi model with dispersive coupling under strong driving. The response to a weak probe is calculated using the Floquet method, which allows us to calculate the probe spectrum and extract the resonance frequency. We test our predictions using a superconducting circuit consisting o… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.00588v2-abstract-full').style.display = 'inline'; document.getElementById('1710.00588v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.00588v2-abstract-full" style="display: none;"> We study numerically the onset of higher-level excitations and resonance frequency shifts in the generalized multilevel Rabi model with dispersive coupling under strong driving. The response to a weak probe is calculated using the Floquet method, which allows us to calculate the probe spectrum and extract the resonance frequency. We test our predictions using a superconducting circuit consisting of transmon coupled capacitively to a coplanar waveguide resonator. This system is monitored by a weak probe field, and at the same time driven at various powers by a stronger microwave tone. We show that the transition from the quantum to the classical regime is accompanied by a rapid increase of the transmon occupation and, consequently that the qubit approximation is valid only in the extreme quantum limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.00588v2-abstract-full').style.display = 'none'; document.getElementById('1710.00588v2-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 June, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 October, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2017. </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, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Low Temp. Phys. (2018) 191: 354 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1709.03731">arXiv:1709.03731</a> <span> [<a href="https://arxiv.org/pdf/1709.03731">pdf</a>, <a href="https://arxiv.org/format/1709.03731">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 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/10.1002/qute.201900121">10.1002/qute.201900121 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Simulating spin chains using a superconducting circuit: gauge invariance, superadiabatic transport, and broken time-reversal symmetry </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="1709.03731v4-abstract-short" style="display: inline;"> Simulation of materials by using quantum processors is envisioned to be a major direction of development in quantum information science. Here we exploit the mathematical analogies between a triangular spin lattice with Dzyaloshinskii-Moriya coupling on one edge and a three-level system driven by three fields in a loop configuation to emulate spin-transport effects. We show that the spin transport… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.03731v4-abstract-full').style.display = 'inline'; document.getElementById('1709.03731v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1709.03731v4-abstract-full" style="display: none;"> Simulation of materials by using quantum processors is envisioned to be a major direction of development in quantum information science. Here we exploit the mathematical analogies between a triangular spin lattice with Dzyaloshinskii-Moriya coupling on one edge and a three-level system driven by three fields in a loop configuation to emulate spin-transport effects. We show that the spin transport efficiency, seen in the three-level system as population transfer, is enhanced when the conditions for superadiabaticity are satisfied. We demonstrate experimentally that phenomena characteristic to spin lattices due to gauge invariance, non-reciprocity, and broken time-reversal symmetry can be reproduced in the three-level system. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1709.03731v4-abstract-full').style.display = 'none'; document.getElementById('1709.03731v4-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 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 September, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2017. </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">18 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Adv. Quantum Technol. 3, 1900121 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1704.00581">arXiv:1704.00581</a> <span> [<a href="https://arxiv.org/pdf/1704.00581">pdf</a>, <a href="https://arxiv.org/format/1704.00581">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 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/10.1002/prop.201600077">10.1002/prop.201600077 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Advances in quantum control of three-level superconducting circuit architectures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Falci%2C+G">G. Falci</a>, <a href="/search/?searchtype=author&query=Di+Stefano%2C+P+G">P. G. Di Stefano</a>, <a href="/search/?searchtype=author&query=Ridolfo%2C+A">A. Ridolfo</a>, <a href="/search/?searchtype=author&query=D%27Arrigo%2C+A">A. D'Arrigo</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">E. Paladino</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="1704.00581v1-abstract-short" style="display: inline;"> Advanced control in Lambda ($螞$) scheme of a solid state architecture of artificial atoms and quantized modes would allow the translation to the solid-state realm of a whole class of phenomena from quantum optics, thus exploiting new physics emerging in larger integrated quantum networks and for stronger couplings. However control solid-state devices has constraints coming from selection rules, du… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.00581v1-abstract-full').style.display = 'inline'; document.getElementById('1704.00581v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1704.00581v1-abstract-full" style="display: none;"> Advanced control in Lambda ($螞$) scheme of a solid state architecture of artificial atoms and quantized modes would allow the translation to the solid-state realm of a whole class of phenomena from quantum optics, thus exploiting new physics emerging in larger integrated quantum networks and for stronger couplings. However control solid-state devices has constraints coming from selection rules, due to symmetries which on the other hand yield protection from decoherence, and from design issues, for instance that coupling to microwave cavities is not directly switchable. We present two new schemes for the $螞$-STIRAP control problem with the constraint of one or two classical driving fields being always-on. We show how these protocols are converted to apply to circuit-QED architectures. We finally illustrate an application to coherent spectroscopy of the so called ultrastrong atom-cavity coupling regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.00581v1-abstract-full').style.display = 'none'; document.getElementById('1704.00581v1-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 April, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2017. </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. Received 27 June 2016, accepted 23 September 2016</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Fortschritte der Physik volume 65, issue 6-8, 2016. P1600077 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1611.09039">arXiv:1611.09039</a> <span> [<a href="https://arxiv.org/pdf/1611.09039">pdf</a>, <a href="https://arxiv.org/format/1611.09039">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> <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="Optics">physics.optics</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/10.3390/photonics3040062">10.3390/photonics3040062 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum Control in Qutrit Systems using Hybrid Rabi-STIRAP Pulses </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">Antti Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">Sergey Danilin</a>, <a href="/search/?searchtype=author&query=Paladino%2C+E">Elisabetta Paladino</a>, <a href="/search/?searchtype=author&query=Falci%2C+G">Giuseppe Falci</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="1611.09039v1-abstract-short" style="display: inline;"> We introduce and analyze theoretically a procedure that combines slow adiabatic STIRAP manipulation with short nonadiabatic Rabi pulses to produce any desired three-level state in a qutrit system. In this protocol, the fast pulses create superpositions between the ground state and the first excited state, while the slow pulses transfer an arbitrary population to the second excited state via stimul… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09039v1-abstract-full').style.display = 'inline'; document.getElementById('1611.09039v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1611.09039v1-abstract-full" style="display: none;"> We introduce and analyze theoretically a procedure that combines slow adiabatic STIRAP manipulation with short nonadiabatic Rabi pulses to produce any desired three-level state in a qutrit system. In this protocol, the fast pulses create superpositions between the ground state and the first excited state, while the slow pulses transfer an arbitrary population to the second excited state via stimulated Raman adiabatic passage (STIRAP). We demonstrate high-fidelity quantum control of the level populations and phases and we characterize the errors incurred under the breakdown of adiabaticity. In a configuration where an ancillary state is available, we show how to realize a nondemolition monitoring of the relative phases. These methods are general and can be implemented on any experimental platform where a quantum system with at least three accessible energy levels is available. We discuss here in detail experimental implementations in circuit quantum electrodynamics (QED) based on the results obtained with a transmon, where the control of population using the hybrid Rabi-STIRAP sequence has been achieved. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1611.09039v1-abstract-full').style.display = 'none'; document.getElementById('1611.09039v1-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 November, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2016. </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">22 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Photonics 3(4), 62 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.09153">arXiv:1610.09153</a> <span> [<a href="https://arxiv.org/pdf/1610.09153">pdf</a>, <a href="https://arxiv.org/format/1610.09153">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="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/10.1103/PhysRevB.96.020501">10.1103/PhysRevB.96.020501 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of the Bloch-Siegert shift in a driven quantum-to-classical transition </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Pietik%C3%A4inen%2C+I">I. Pietik盲inen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Kumar%2C+K+S">K. S. Kumar</a>, <a href="/search/?searchtype=author&query=Veps%C3%A4l%C3%A4inen%2C+A">A. Veps盲l盲inen</a>, <a href="/search/?searchtype=author&query=Golubev%2C+D+S">D. S. Golubev</a>, <a href="/search/?searchtype=author&query=Tuorila%2C+J">J. Tuorila</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1610.09153v2-abstract-short" style="display: inline;"> We show that the counter-rotating terms of the dispersive qubit-cavity Rabi model can produce relatively large and nonmonotonic Bloch-Siegert shifts in the cavity frequency as the system is driven through a quantum-to-classical transition. Using a weak microwave probe tone, we demonstrate experimentally this effect by monitoring the resonance frequency of a microwave cavity coupled to a transmon a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.09153v2-abstract-full').style.display = 'inline'; document.getElementById('1610.09153v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.09153v2-abstract-full" style="display: none;"> We show that the counter-rotating terms of the dispersive qubit-cavity Rabi model can produce relatively large and nonmonotonic Bloch-Siegert shifts in the cavity frequency as the system is driven through a quantum-to-classical transition. Using a weak microwave probe tone, we demonstrate experimentally this effect by monitoring the resonance frequency of a microwave cavity coupled to a transmon and driven by a microwave field with varying power. In the weakly driven regime (quantum phase), the Bloch-Siegert shift appears as a small constant frequency shift, while for strong drive (classical phase) it presents an oscillatory behaviour as a function of the number of photons in the cavity. The experimental results are in agreement with numerical simulations based on the quasienergy spectrum. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.09153v2-abstract-full').style.display = 'none'; document.getElementById('1610.09153v2-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 August, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2016. </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">Main text (5+ pages and 4 figures) and Supplementary Information (13 pages and 7 figures). Updated to published version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 96, 020501 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1607.05043">arXiv:1607.05043</a> <span> [<a href="https://arxiv.org/pdf/1607.05043">pdf</a>, <a href="https://arxiv.org/format/1607.05043">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 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/PhysRevA.95.062324">10.1103/PhysRevA.95.062324 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Entanglement, coherence, and redistribution of quantum resources in double spontaneous downconversion processes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Bruschi%2C+D+E">David Edward Bruschi</a>, <a href="/search/?searchtype=author&query=Sab%C3%ADn%2C+C">Carlos Sab铆n</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</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="1607.05043v3-abstract-short" style="display: inline;"> We study the properties of bi-squeezed tripartite Gaussian states created by two spontaneous parametric down-conversion processes that share a common idler. We give a complete description of the quantum correlations across of all partitions, as well as of the genuine multipartite entanglement, obtaining analytical expressions for most of the quantities of interest. We find that the state contains… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05043v3-abstract-full').style.display = 'inline'; document.getElementById('1607.05043v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.05043v3-abstract-full" style="display: none;"> We study the properties of bi-squeezed tripartite Gaussian states created by two spontaneous parametric down-conversion processes that share a common idler. We give a complete description of the quantum correlations across of all partitions, as well as of the genuine multipartite entanglement, obtaining analytical expressions for most of the quantities of interest. We find that the state contains genuine tripartite entanglement, in addition to the bipartite entanglement among the modes that are directly squeezed. We also investigate the effect of homodyne detection of the photons in the common idler mode, and analyse the final reduced state of the remaining two signal modes. We find that this measurement leads to a conversion of the coherence of the two signal modes into entanglement, a phenomenon that can be regarded as a redistribution of quantum resources between the modes. The applications of these results to quantum optics and circuit quantum electrodynamics platforms are also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05043v3-abstract-full').style.display = 'none'; document.getElementById('1607.05043v3-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 June, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 18 July, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2016. </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">18 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 95, 062324 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.05561">arXiv:1512.05561</a> <span> [<a href="https://arxiv.org/pdf/1512.05561">pdf</a>, <a href="https://arxiv.org/format/1512.05561">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="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/10.1038/ncomms12548">10.1038/ncomms12548 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Coherence and multimode correlations from vacuum fluctuations in a microwave superconducting cavity </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=L%C3%A4hteenm%C3%A4ki%2C+P">Pasi L盲hteenm盲ki</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">Gheorghe Sorin Paraoanu</a>, <a href="/search/?searchtype=author&query=Hassel%2C+J">Juha Hassel</a>, <a href="/search/?searchtype=author&query=Hakonen%2C+P+J">Pertti J. 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="1512.05561v2-abstract-short" style="display: inline;"> The existence of vacuum fluctuations is one of the most important predictions of modern quantum field theory. In the vacuum state, fluctuations occurring at different frequencies are uncorrelated. However, if a parameter in the Lagrangian of the field is modulated by an external pump, vacuum fluctuations stimulate spontaneous downconversion processes, creating squeezing between modes symmetric wit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.05561v2-abstract-full').style.display = 'inline'; document.getElementById('1512.05561v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.05561v2-abstract-full" style="display: none;"> The existence of vacuum fluctuations is one of the most important predictions of modern quantum field theory. In the vacuum state, fluctuations occurring at different frequencies are uncorrelated. However, if a parameter in the Lagrangian of the field is modulated by an external pump, vacuum fluctuations stimulate spontaneous downconversion processes, creating squeezing between modes symmetric with respect to half of the frequency of the pump. Here we show that by double parametric pumping of a superconducting microwave cavity, it is possible to generate another fundamental type of correlation, namely coherence between photons in separate frequency modes. The coherence correlations are tunable by the phases of the pumps and are established by a quantum fluctuation that stimulates the simultaneous creation of two photon pairs. Our analysis indicates that the origin of this vacuum-induced coherence is the absence of 'which-way' information in the frequency space. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.05561v2-abstract-full').style.display = 'none'; document.getElementById('1512.05561v2-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 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 7, 12548 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1512.04027">arXiv:1512.04027</a> <span> [<a href="https://arxiv.org/pdf/1512.04027">pdf</a>, <a href="https://arxiv.org/format/1512.04027">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> <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/10.1088/1361-6633/aa5170">10.1088/1361-6633/aa5170 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum systems under frequency modulation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Silveri%2C+M+P">M. P. Silveri</a>, <a href="/search/?searchtype=author&query=Tuorila%2C+J+A">J. A. Tuorila</a>, <a href="/search/?searchtype=author&query=Thuneberg%2C+E+V">E. V. Thuneberg</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1512.04027v2-abstract-short" style="display: inline;"> We review the physical phenomena that arise when quantum mechanical energy levels are modulated in time. The dynamics resulting from changes in the transition frequency is a problem studied since the early days of quantum mechanics. It has been of constant interest both experimentally and theoretically since, with the simple two-state model providing an inexhaustible source of novel concepts. When… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.04027v2-abstract-full').style.display = 'inline'; document.getElementById('1512.04027v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1512.04027v2-abstract-full" style="display: none;"> We review the physical phenomena that arise when quantum mechanical energy levels are modulated in time. The dynamics resulting from changes in the transition frequency is a problem studied since the early days of quantum mechanics. It has been of constant interest both experimentally and theoretically since, with the simple two-state model providing an inexhaustible source of novel concepts. When the transition frequency of a quantum system is modulated, several phenomena can be observed, such as Landau-Zener-St眉ckelberg-Majorana interference, motional averaging and narrowing, and the formation of dressed states with the presence of sidebands in the spectrum. Adiabatic changes result in the accumulation of geometric phases, which can be used to create topological states. In recent years, an exquisite experimental control in the time domain was gained through the parameters entering the Hamiltonian, and high-fidelity readout schemes allowed the state of the system to be monitored non-destructively. These developments were made in the field of quantum devices, especially in superconducting qubits, as a well as in atomic physics, in particular in ultracold gases. As a result of these advances, it became possible to demonstrate many of the fundamental effects that arise in a quantum system when its transition frequencies are modulated. The purpose of this review is to present some of these developments, from two-state atoms and harmonic oscillators to multilevel and many-particle systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1512.04027v2-abstract-full').style.display = 'none'; document.getElementById('1512.04027v2-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 February, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 December, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2015. </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">review article (77 pages, 13 figures)</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Rep. Prog. Phys. 80, 056002 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1508.02981">arXiv:1508.02981</a> <span> [<a href="https://arxiv.org/pdf/1508.02981">pdf</a>, <a href="https://arxiv.org/format/1508.02981">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> <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/ncomms10628">10.1038/ncomms10628 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stimulated Raman adiabatic passage in a three-level superconducting circuit </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/?searchtype=author&query=Kumar%2C+K+S">K. S. Kumar</a>, <a href="/search/?searchtype=author&query=Vepsalainen%2C+A">A. Vepsalainen</a>, <a href="/search/?searchtype=author&query=Danilin%2C+S">S. Danilin</a>, <a href="/search/?searchtype=author&query=Paraoanu%2C+G+S">G. S. Paraoanu</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="1508.02981v1-abstract-short" style="display: inline;"> The adiabatic manipulation of quantum states is a powerful technique that has opened up new directions in quantum engineering, enabling tests of fundamental concepts such as the Berry phase and its nonabelian generalization, the observation of topological transitions, and holds the promise of alternative models of quantum computation. Here we benchmark the stimulated Raman adiabatic passage proces… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.02981v1-abstract-full').style.display = 'inline'; document.getElementById('1508.02981v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1508.02981v1-abstract-full" style="display: none;"> The adiabatic manipulation of quantum states is a powerful technique that has opened up new directions in quantum engineering, enabling tests of fundamental concepts such as the Berry phase and its nonabelian generalization, the observation of topological transitions, and holds the promise of alternative models of quantum computation. Here we benchmark the stimulated Raman adiabatic passage process for circuit quantum electrodynamics, by using the first three levels of a transmon qubit. We demonstrate a population transfer efficiency above 80% between the ground state and the second excited state using two adiabatic Gaussian-shaped control microwave pulses coupled to the first and second transition. The advantage of this techniques is robustness against errors in the timing of the control pulses. By doing quantum tomography at successive moments during the Raman pulses, we investigate the transfer of the population in time-domain. We also show that this protocol can be reversed by applying a third adiabatic pulse on the first transition. Furthermore, we demonstrate a hybrid adiabatic-nonadiabatic gate using a fast pulse followed by the adiabatic Raman sequence, and we study experimentally the case of a quasi-degenerate intermediate level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1508.02981v1-abstract-full').style.display = 'none'; document.getElementById('1508.02981v1-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> 12 August, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2015. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 7, 10628 (2016) </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 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