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<button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Curty%2C+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Curty%2C+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Curty%2C+M&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/2411.13948">arXiv:2411.13948</a> <span> [<a href="https://arxiv.org/pdf/2411.13948">pdf</a>, <a href="https://arxiv.org/format/2411.13948">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"> Quantum key distribution with imperfectly isolated devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sixto%2C+X">Xoel Sixto</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2411.13948v1-abstract-short" style="display: inline;"> Most security proofs of quantum key distribution (QKD) assume that there is no unwanted information leakage about the state preparation process. However, this assumption is impossible to guarantee in practice, as QKD systems can leak information to the channel due to device imperfections or the active action of an eavesdropper. Here, we solve this pressing issue by introducing a security proof in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.13948v1-abstract-full').style.display = 'inline'; document.getElementById('2411.13948v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.13948v1-abstract-full" style="display: none;"> Most security proofs of quantum key distribution (QKD) assume that there is no unwanted information leakage about the state preparation process. However, this assumption is impossible to guarantee in practice, as QKD systems can leak information to the channel due to device imperfections or the active action of an eavesdropper. Here, we solve this pressing issue by introducing a security proof in the presence of information leakage from all state preparation settings for arguably the most popular QKD scheme, namely the decoy-state BB84 protocol. The proof requires minimal experimental characterization, as only a single parameter related to the isolation of the source needs to be determined, thus providing a clear path for bridging the gap between theory and practice. Moreover, if information about the state of the side channels is available, this can be readily incorporated into the analysis to further improve the resulting performance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.13948v1-abstract-full').style.display = 'none'; document.getElementById('2411.13948v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 21 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">18 pages, 10 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/2411.00709">arXiv:2411.00709</a> <span> [<a href="https://arxiv.org/pdf/2411.00709">pdf</a>, <a href="https://arxiv.org/format/2411.00709">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"> Intensity correlations in decoy-state BB84 quantum key distribution systems </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Trefilov%2C+D">Daniil Trefilov</a>, <a href="/search/quant-ph?searchtype=author&query=Sixto%2C+X">Xoel Sixto</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+A">Anqi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Makarov%2C+V">Vadim Makarov</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="2411.00709v1-abstract-short" style="display: inline;"> The decoy-state method is a prominent approach to enhance the performance of quantum key distribution (QKD) systems that operate with weak coherent laser sources. Due to the limited transmissivity of single photons in optical fiber, current experimental decoy-state QKD setups increase their secret key rate by raising the repetition rate of the transmitter. However, this usually leads to correlatio… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00709v1-abstract-full').style.display = 'inline'; document.getElementById('2411.00709v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2411.00709v1-abstract-full" style="display: none;"> The decoy-state method is a prominent approach to enhance the performance of quantum key distribution (QKD) systems that operate with weak coherent laser sources. Due to the limited transmissivity of single photons in optical fiber, current experimental decoy-state QKD setups increase their secret key rate by raising the repetition rate of the transmitter. However, this usually leads to correlations between subsequent optical pulses. This phenomenon leaks information about the encoding settings, including the intensities of the generated signals, which invalidates a basic premise of decoy-state QKD. Here we characterize intensity correlations between the emitted optical pulses in two industrial prototypes of decoy-state BB84 QKD systems and show that they significantly reduce the asymptotic key rate. In contrast to what has been conjectured, we experimentally confirm that the impact of higher-order correlations on the intensity of the generated signals can be much higher than that of nearest-neighbour correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2411.00709v1-abstract-full').style.display = 'none'; document.getElementById('2411.00709v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 November, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">15 pages, 8 figures, 2 tables</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2410.04095">arXiv:2410.04095</a> <span> [<a href="https://arxiv.org/pdf/2410.04095">pdf</a>, <a href="https://arxiv.org/format/2410.04095">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"> Sharp finite statistics for minimum data block sizes in quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mannalath%2C+V">Vaisakh Mannalath</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2410.04095v1-abstract-short" style="display: inline;"> The performance of quantum key distribution (QKD) heavily depends on the finite statistics of its security proof. For multiple protocols and proof techniques, the central statistical task is a random sampling problem, which is customarily addressed by invoking suitable tail bounds on the hypergeometric distribution. In this work, we introduce an alternative solution that exploits a link between ra… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04095v1-abstract-full').style.display = 'inline'; document.getElementById('2410.04095v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.04095v1-abstract-full" style="display: none;"> The performance of quantum key distribution (QKD) heavily depends on the finite statistics of its security proof. For multiple protocols and proof techniques, the central statistical task is a random sampling problem, which is customarily addressed by invoking suitable tail bounds on the hypergeometric distribution. In this work, we introduce an alternative solution that exploits a link between random sampling with and without replacement. Despite its simplicity, it notably boosts the achievable secret key rate, particularly in the regime of small data block sizes critical for satellite QKD and other envisioned QKD applications. Moreover, as a by-product of the proposed tool, tight Neyman constructions are derived for the average of independent Bernoulli variables. Bounds of this kind naturally fit in finite-key security proofs of decoy-state QKD schemes, further sharpening the finite statistics compared to previous approaches. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.04095v1-abstract-full').style.display = 'none'; document.getElementById('2410.04095v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">15 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2406.13760">arXiv:2406.13760</a> <span> [<a href="https://arxiv.org/pdf/2406.13760">pdf</a>, <a href="https://arxiv.org/format/2406.13760">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/10.1088/2058-9565/ad4f0c">10.1088/2058-9565/ad4f0c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Hacking coherent-one-way quantum key distribution with present-day technology </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rey-Dom%C3%ADnguez%2C+J">Javier Rey-Dom铆nguez</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=van+Loock%2C+P">Peter van Loock</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2406.13760v1-abstract-short" style="display: inline;"> Recent results have shown that the secret-key rate of coherent-one-way (COW) quantum key distribution (QKD) scales quadratically with the system's transmittance, thus rendering this protocol unsuitable for long-distance transmission. This was proven by using a so-called zero-error attack, which relies on an unambiguous state discrimination (USD) measurement. This type of attack allows the eavesdro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.13760v1-abstract-full').style.display = 'inline'; document.getElementById('2406.13760v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2406.13760v1-abstract-full" style="display: none;"> Recent results have shown that the secret-key rate of coherent-one-way (COW) quantum key distribution (QKD) scales quadratically with the system's transmittance, thus rendering this protocol unsuitable for long-distance transmission. This was proven by using a so-called zero-error attack, which relies on an unambiguous state discrimination (USD) measurement. This type of attack allows the eavesdropper to learn the whole secret key without introducing any error. Here, we investigate the feasibility and effectiveness of zero-error attacks against COW QKD with present-day technology. For this, we introduce two practical USD receivers that can be realized with linear passive optical elements, phase-space displacement operations and threshold single-photon detectors. The first receiver is optimal with respect to its success probability, while the second one can impose stronger restrictions on the protocol's performance with faulty eavesdropping equipment. Our findings suggest that zero-error attacks could break the security of COW QKD even assuming realistic experimental conditions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2406.13760v1-abstract-full').style.display = 'none'; document.getElementById('2406.13760v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 June, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Sci. Technol. 9, 035044 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.08028">arXiv:2402.08028</a> <span> [<a href="https://arxiv.org/pdf/2402.08028">pdf</a>, <a href="https://arxiv.org/format/2402.08028">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/10.1088/2058-9565/ad8181">10.1088/2058-9565/ad8181 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum key distribution with unbounded pulse correlations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Rusca%2C+D">Davide Rusca</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</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="2402.08028v1-abstract-short" style="display: inline;"> A prevalent issue in practical applications of quantum key distribution (QKD) is the emergence of correlations among the emitted signals. Although recent works have proved the security of QKD in the presence of this imperfection, they rest on the premise that pulse correlations are of finite length. However, this assumption is not necessarily met in practice, since the length of these correlations… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.08028v1-abstract-full').style.display = 'inline'; document.getElementById('2402.08028v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.08028v1-abstract-full" style="display: none;"> A prevalent issue in practical applications of quantum key distribution (QKD) is the emergence of correlations among the emitted signals. Although recent works have proved the security of QKD in the presence of this imperfection, they rest on the premise that pulse correlations are of finite length. However, this assumption is not necessarily met in practice, since the length of these correlations could be potentially unbounded. Indeed, the first emitted pulse could be correlated with the last one, even if very faintly. Still, intuitively, there should exist a pulse separation threshold after which these correlations become so small as to be essentially negligible, rendering them inconsequential from a security standpoint. Building on this insight, we introduce a general formalism designed to extend existing security proofs to the practically relevant scenario in which pulse correlations have an unbounded length. This approach significantly enhances the applicability of these proofs and the robustness of QKD's implementation security. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.08028v1-abstract-full').style.display = 'none'; document.getElementById('2402.08028v1-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, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Sci. Technol. 10 015001 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.20377">arXiv:2310.20377</a> <span> [<a href="https://arxiv.org/pdf/2310.20377">pdf</a>, <a href="https://arxiv.org/format/2310.20377">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"> Implementation security in quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2310.20377v1-abstract-short" style="display: inline;"> The problem of implementation security in quantum key distribution (QKD) refers to the difficulty of meeting the requirements of mathematical security proofs in real-life QKD systems. Here, we provide a succint review on this topic, focusing on discrete variable QKD setups. Particularly, we discuss some of their main vulnerabilities and comment on possible approaches to overcome them. </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.20377v1-abstract-full" style="display: none;"> The problem of implementation security in quantum key distribution (QKD) refers to the difficulty of meeting the requirements of mathematical security proofs in real-life QKD systems. Here, we provide a succint review on this topic, focusing on discrete variable QKD setups. Particularly, we discuss some of their main vulnerabilities and comment on possible approaches to overcome them. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.20377v1-abstract-full').style.display = 'none'; document.getElementById('2310.20377v1-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> 31 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">Submitted to Advanced Quantum Technologies</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2308.02376">arXiv:2308.02376</a> <span> [<a href="https://arxiv.org/pdf/2308.02376">pdf</a>, <a href="https://arxiv.org/format/2308.02376">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"> Finite-key security of passive quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2308.02376v1-abstract-short" style="display: inline;"> The passive approach to quantum key distribution (QKD) consists of eliminating all optical modulators and random number generators from QKD systems, in so reaching an enhanced simplicity, immunity to modulator side channels, and potentially higher repetition rates. In this work, we provide finite-key security bounds for a fully passive decoy-state BB84 protocol, considering a passive QKD source re… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02376v1-abstract-full').style.display = 'inline'; document.getElementById('2308.02376v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2308.02376v1-abstract-full" style="display: none;"> The passive approach to quantum key distribution (QKD) consists of eliminating all optical modulators and random number generators from QKD systems, in so reaching an enhanced simplicity, immunity to modulator side channels, and potentially higher repetition rates. In this work, we provide finite-key security bounds for a fully passive decoy-state BB84 protocol, considering a passive QKD source recently presented. With our analysis, the attainable secret key rate is comparable to that of the perfect parameter estimation limit, in fact differing from the key rate of the active approach by less than one order of magnitude. This demonstrates the practicality of fully passive QKD solutions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2308.02376v1-abstract-full').style.display = 'none'; document.getElementById('2308.02376v1-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 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/2305.05930">arXiv:2305.05930</a> <span> [<a href="https://arxiv.org/pdf/2305.05930">pdf</a>, <a href="https://arxiv.org/format/2305.05930">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"> A security framework for quantum key distribution implementations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</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="2305.05930v2-abstract-short" style="display: inline;"> Quantum key distribution (QKD) can theoretically achieve the Holy Grail of cryptography, information-theoretic security against eavesdropping. However, in practice, discrepancies between the mathematical models assumed in security proofs and the actual functioning of the devices used in implementations prevent it from reaching this goal. Device-independent QKD is currently not a satisfactory solut… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05930v2-abstract-full').style.display = 'inline'; document.getElementById('2305.05930v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2305.05930v2-abstract-full" style="display: none;"> Quantum key distribution (QKD) can theoretically achieve the Holy Grail of cryptography, information-theoretic security against eavesdropping. However, in practice, discrepancies between the mathematical models assumed in security proofs and the actual functioning of the devices used in implementations prevent it from reaching this goal. Device-independent QKD is currently not a satisfactory solution to this problem, as its performance is extremely poor and most of its security proofs assume that the user devices leak absolutely no information to the outside. On the other hand, measurement-device-independent (MDI) QKD can guarantee security with arbitrarily flawed receivers while achieving high performance, and the remaining challenge is ensuring its security in the presence of source imperfections. So far, all efforts in this regard have come at a price; some proofs are suitable only for particular source imperfections, while others severely compromise the system's performance, i.e., its communication speed and distance. Here, we overcome these crucial problems by presenting a security proof in the finite-key regime against coherent attacks that can incorporate general encoding imperfections and side channels while achieving much higher performances than previous approaches. Moreover, our proof requires minimal state characterization, which facilitates its application to real-life implementations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2305.05930v2-abstract-full').style.display = 'none'; document.getElementById('2305.05930v2-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 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 10 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">Main text: 9 pages, 3 figures. Supplementary information: 63 pages, 12 figures. v2: Added many improvements and extensions to the security proof, including: (1) analysis in finite-key regime, (2) inclusion of measurement-device-independent type protocols, (3) consideration of sources that emit weak coherent pulses, (4) consideration of sources that introduce correlations across consecutive pulses</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2304.11655">arXiv:2304.11655</a> <span> [<a href="https://arxiv.org/pdf/2304.11655">pdf</a>, <a href="https://arxiv.org/format/2304.11655">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"> Experimental demonstration of fully passive quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lu%2C+F">Feng-Yu Lu</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Ze-Hao Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+J">Jia-Lin Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+S">Shuang Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Yin%2C+Z">Zhen-Qiang Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=He%2C+D">De-Yong He</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+R">Rong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+W">Wei Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Fan-Yuan%2C+G">Guan-Jie Fan-Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Guo%2C+G">Guang-Can Guo</a>, <a href="/search/quant-ph?searchtype=author&query=Han%2C+Z">Zheng-Fu Han</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="2304.11655v2-abstract-short" style="display: inline;"> The passive approach to quantum key distribution (QKD) consists of removing all active modulation from the users' devices, a highly desirable countermeasure to get rid of modulator side-channels. Nevertheless, active modulation has not been completely removed in QKD systems so far, due to both theoretical and practical limitations. In this work, we present a fully passive time-bin encoding QKD sys… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11655v2-abstract-full').style.display = 'inline'; document.getElementById('2304.11655v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.11655v2-abstract-full" style="display: none;"> The passive approach to quantum key distribution (QKD) consists of removing all active modulation from the users' devices, a highly desirable countermeasure to get rid of modulator side-channels. Nevertheless, active modulation has not been completely removed in QKD systems so far, due to both theoretical and practical limitations. In this work, we present a fully passive time-bin encoding QKD system and report on the successful implementation of a modulator-free QKD link. According to the latest theoretical analysis, our prototype is capable of delivering competitive secret key rates in the finite key regime. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.11655v2-abstract-full').style.display = 'none'; document.getElementById('2304.11655v2-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 August, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 23 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">13 pages, 5 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/2304.03562">arXiv:2304.03562</a> <span> [<a href="https://arxiv.org/pdf/2304.03562">pdf</a>, <a href="https://arxiv.org/format/2304.03562">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/10.1140/epjqt/s40507-023-00210-0">10.1140/epjqt/s40507-023-00210-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Secret key rate bounds for quantum key distribution with non-uniform phase randomization </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sixto%2C+X">Xoel Sixto</a>, <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2304.03562v1-abstract-short" style="display: inline;"> Decoy-state quantum key distribution (QKD) is undoubtedly the most efficient solution to handle multi-photon signals emitted by laser sources, and provides the same secret key rate scaling as ideal single-photon sources. It requires, however, that the phase of each emitted pulse is uniformly random. This might be difficult to guarantee in practice, due to inevitable device imperfections and/or the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.03562v1-abstract-full').style.display = 'inline'; document.getElementById('2304.03562v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2304.03562v1-abstract-full" style="display: none;"> Decoy-state quantum key distribution (QKD) is undoubtedly the most efficient solution to handle multi-photon signals emitted by laser sources, and provides the same secret key rate scaling as ideal single-photon sources. It requires, however, that the phase of each emitted pulse is uniformly random. This might be difficult to guarantee in practice, due to inevitable device imperfections and/or the use of an external phase modulator for phase randomization, which limits the possible selected phases to a finite set. Here, we investigate the security of decoy-state QKD with arbitrary, continuous or discrete, non-uniform phase randomization, and show that this technique is quite robust to deviations from the ideal uniformly random scenario. For this, we combine a novel parameter estimation technique based on semi-definite programming, with the use of basis mismatched events, to tightly estimate the parameters that determine the achievable secret key rate. In doing so, we demonstrate that our analysis can significantly outperform previous results that address more restricted scenarios. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2304.03562v1-abstract-full').style.display = 'none'; document.getElementById('2304.03562v1-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 April, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> EPJ Quantum Technol. 10, 53 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.11754">arXiv:2210.11754</a> <span> [<a href="https://arxiv.org/pdf/2210.11754">pdf</a>, <a href="https://arxiv.org/format/2210.11754">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"> Modified BB84 quantum key distribution protocol robust to source imperfections </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.11754v1-abstract-short" style="display: inline;"> The Bennett-Brassard 1984 (BB84) protocol is the most widely implemented quantum key distribution (QKD) scheme. However, despite enormous theoretical and experimental efforts in the past decades, the security of this protocol with imperfect sources has not yet been rigorously established. In this work, we address this shortcoming and prove the security of the BB84 protocol in the presence of multi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.11754v1-abstract-full').style.display = 'inline'; document.getElementById('2210.11754v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.11754v1-abstract-full" style="display: none;"> The Bennett-Brassard 1984 (BB84) protocol is the most widely implemented quantum key distribution (QKD) scheme. However, despite enormous theoretical and experimental efforts in the past decades, the security of this protocol with imperfect sources has not yet been rigorously established. In this work, we address this shortcoming and prove the security of the BB84 protocol in the presence of multiple source imperfections, including state preparation flaws and side channels, such as Trojan-horse attacks, mode dependencies and classical correlations between the emitted pulses. To do so, we consider a modified BB84 protocol that exploits the basis mismatched events, which are often discarded in standard security analyses of this scheme; and employ the reference technique, a powerful mathematical tool to accommodate source imperfections in the security analysis of QKD. Moreover, we compare the achievable secret-key rate of the modified BB84 protocol with that of the three-state loss-tolerant protocol, and show that the addition of a fourth state, while redundant in ideal conditions, significantly improves the estimation of the leaked information in the presence of source imperfections, resulting in a better performance. This work demonstrates the relevance of the BB84 protocol in guaranteeing implementation security, taking us a step further towards closing the existing gap between theory and practice of QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.11754v1-abstract-full').style.display = 'none'; document.getElementById('2210.11754v1-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 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Research 5, 023065 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.08183">arXiv:2210.08183</a> <span> [<a href="https://arxiv.org/pdf/2210.08183">pdf</a>, <a href="https://arxiv.org/format/2210.08183">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/10.1088/2058-9565/ad141c">10.1088/2058-9565/ad141c <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security of quantum key distribution with imperfect phase randomisation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Nahar%2C+S">Shlok Nahar</a>, <a href="/search/quant-ph?searchtype=author&query=L%C3%BCtkenhaus%2C+N">Norbert L眉tkenhaus</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.08183v3-abstract-short" style="display: inline;"> The performance of quantum key distribution (QKD) is severely limited by multiphoton emissions, due to the photon-number-splitting attack. The most efficient solution, the decoy-state method, requires that the phases of all transmitted pulses are independent and uniformly random. In practice, however, these phases are often correlated, especially in high-speed systems, which opens a security looph… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.08183v3-abstract-full').style.display = 'inline'; document.getElementById('2210.08183v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.08183v3-abstract-full" style="display: none;"> The performance of quantum key distribution (QKD) is severely limited by multiphoton emissions, due to the photon-number-splitting attack. The most efficient solution, the decoy-state method, requires that the phases of all transmitted pulses are independent and uniformly random. In practice, however, these phases are often correlated, especially in high-speed systems, which opens a security loophole. Here, we address this pressing problem by providing a security proof for decoy-state QKD with correlated phases that offers key rates close to the ideal scenario. Our work paves the way towards high-performance secure QKD with practical laser sources, and may have applications beyond QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.08183v3-abstract-full').style.display = 'none'; document.getElementById('2210.08183v3-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 January, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 pages, 1 figure. v3: Updated to Accepted Manuscript</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Sci. Technol. 9, 015025 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.12842">arXiv:2208.12842</a> <span> [<a href="https://arxiv.org/pdf/2208.12842">pdf</a>, <a href="https://arxiv.org/format/2208.12842">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/s41534-023-00684-x">10.1038/s41534-023-00684-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Advances in device-independent quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=van+Leent%2C+T">Tim van Leent</a>, <a href="/search/quant-ph?searchtype=author&query=Arnon-Friedman%2C+R">Rotem Arnon-Friedman</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wen-Zhao Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Weinfurter%2C+H">Harald Weinfurter</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.12842v1-abstract-short" style="display: inline;"> Device-independent quantum key distribution (DI-QKD) provides the gold standard for secure key exchange. Not only it allows for information-theoretic security based on quantum mechanics, but it relaxes the need to physically model the devices, hence fundamentally ruling out many quantum hacking threats to which non-DI QKD systems are vulnerable. In practice though, DI-QKD is very challenging. It r… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12842v1-abstract-full').style.display = 'inline'; document.getElementById('2208.12842v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.12842v1-abstract-full" style="display: none;"> Device-independent quantum key distribution (DI-QKD) provides the gold standard for secure key exchange. Not only it allows for information-theoretic security based on quantum mechanics, but it relaxes the need to physically model the devices, hence fundamentally ruling out many quantum hacking threats to which non-DI QKD systems are vulnerable. In practice though, DI-QKD is very challenging. It relies on the loophole-free violation of a Bell inequality, a task that requires high quality entanglement to be distributed between distant parties and close to perfect quantum measurements, which is hardly achievable with current technology. Notwithstanding, recent theoretical and experimental efforts have led to the first proof-of-principle DI-QKD implementations. In this article, we review the state-of-the-art of DI-QKD by highlighting its main theoretical and experimental achievements, discussing the recent proof-of-principle demonstrations, and emphasizing the existing challenges in the field. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12842v1-abstract-full').style.display = 'none'; document.getElementById('2208.12842v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 9, 10 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2208.12516">arXiv:2208.12516</a> <span> [<a href="https://arxiv.org/pdf/2208.12516">pdf</a>, <a href="https://arxiv.org/format/2208.12516">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/10.1088/2058-9565/acbc46">10.1088/2058-9565/acbc46 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A fully passive transmitter for decoy-state quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wenyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2208.12516v2-abstract-short" style="display: inline;"> A passive quantum key distribution (QKD) transmitter generates the quantum states prescribed by a QKD protocol at random, combining a fixed quantum mechanism and a post-selection step. By avoiding the use of active optical modulators externally driven by random number generators, passive QKD transmitters offer immunity to modulator side channels and potentially enable higher frequencies of operati… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12516v2-abstract-full').style.display = 'inline'; document.getElementById('2208.12516v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2208.12516v2-abstract-full" style="display: none;"> A passive quantum key distribution (QKD) transmitter generates the quantum states prescribed by a QKD protocol at random, combining a fixed quantum mechanism and a post-selection step. By avoiding the use of active optical modulators externally driven by random number generators, passive QKD transmitters offer immunity to modulator side channels and potentially enable higher frequencies of operation. Recently, the first linear optics setup suitable for passive decoy-state QKD has been proposed. In this work, we simplify the prototype and adopt sharply different approaches for BB84 polarization encoding and decoy-state generation. On top of it, we elaborate a tight custom-made security analysis surpassing an unnecessary assumption and a post-selection step that are central to the former proposal. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2208.12516v2-abstract-full').style.display = 'none'; document.getElementById('2208.12516v2-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 November, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 August, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Science and Technology 8, 025014 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.05916">arXiv:2207.05916</a> <span> [<a href="https://arxiv.org/pdf/2207.05916">pdf</a>, <a href="https://arxiv.org/format/2207.05916">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/PhysRevLett.130.220801">10.1103/PhysRevLett.130.220801 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Fully-Passive Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wenyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+R">Rong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">Victor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">Li Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Qi%2C+B">Bing Qi</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.05916v1-abstract-short" style="display: inline;"> Passive implementations of quantum key distribution (QKD) sources are highly desirable as they eliminate side-channels that active modulators might introduce. Up till now, passive decoy-state and passive encoding BB84 schemes have both been proposed. Nonetheless, passive decoy-state generation and passive encoding have never been simultaneously implemented with linear optical elements before, whic… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.05916v1-abstract-full').style.display = 'inline'; document.getElementById('2207.05916v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.05916v1-abstract-full" style="display: none;"> Passive implementations of quantum key distribution (QKD) sources are highly desirable as they eliminate side-channels that active modulators might introduce. Up till now, passive decoy-state and passive encoding BB84 schemes have both been proposed. Nonetheless, passive decoy-state generation and passive encoding have never been simultaneously implemented with linear optical elements before, which greatly limits the practicality of such passive QKD schemes. In this work, we overcome this limitation and propose a fully-passive QKD source with linear optics that eliminates active modulators for both decoy-state choice and encoding. This allows for highly practical QKD systems that avoid side-channels from the source modulators. The passive source we propose (combined with the decoy-state analysis) can create any arbitrary state on a qubit system and is protocol-independent. That is, it can be used for various protocols such as BB84, reference-frame-independent QKD, or the six-state protocol. It can also in principle be combined with e.g. measurement-device-independent QKD, to build a system without side-channels in either detectors or modulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.05916v1-abstract-full').style.display = 'none'; document.getElementById('2207.05916v1-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2206.06700">arXiv:2206.06700</a> <span> [<a href="https://arxiv.org/pdf/2206.06700">pdf</a>, <a href="https://arxiv.org/format/2206.06700">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/PhysRevApplied.18.044069">10.1103/PhysRevApplied.18.044069 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security of decoy-state quantum key distribution with correlated intensity fluctuations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sixto%2C+X">Xoel Sixto</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2206.06700v2-abstract-short" style="display: inline;"> One of the most prominent techniques to enhance the performance of practical quantum key distribution (QKD) systems with laser sources is the decoy-state method. Current decoy-state QKD setups operate at GHz repetition rates, a regime where memory effects in the modulators and electronics that control them create correlations between the intensities of the emitted pulses. This translates into info… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.06700v2-abstract-full').style.display = 'inline'; document.getElementById('2206.06700v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.06700v2-abstract-full" style="display: none;"> One of the most prominent techniques to enhance the performance of practical quantum key distribution (QKD) systems with laser sources is the decoy-state method. Current decoy-state QKD setups operate at GHz repetition rates, a regime where memory effects in the modulators and electronics that control them create correlations between the intensities of the emitted pulses. This translates into information leakage about the selected intensities, which cripples a crucial premise of the decoy-state method, thus invalidating the use of standard security analyses. To overcome this problem, a novel security proof that exploits the Cauchy-Schwarz constraint has been introduced recently. Its main drawback is, however, that the achievable key rate is significantly lower than that of the ideal scenario without intensity correlations. Here, we improve this security proof technique by combining it with a fine-grained decoy-state analysis, which can deliver a tight estimation of the relevant parameters that determine the secret key rate. This results in a notable performance enhancement, being now the attainable distance double than that of previous analyses for certain parameter regimes. Also, we show that when the probability density function of the intensity fluctuations, conditioned on the current and previous intensity choices, is known, our approach provides a key rate very similar to the ideal scenario, which highlights the importance of an accurate experimental characterization of the correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.06700v2-abstract-full').style.display = 'none'; document.getElementById('2206.06700v2-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 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 14 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">19 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 18, 044069 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.06630">arXiv:2202.06630</a> <span> [<a href="https://arxiv.org/pdf/2202.06630">pdf</a>, <a href="https://arxiv.org/format/2202.06630">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/10.1088/2058-9565/ac74dc">10.1088/2058-9565/ac74dc <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Improved Finite-Key Security Analysis of Quantum Key Distribution Against Trojan-Horse Attacks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2202.06630v1-abstract-short" style="display: inline;"> Most security proofs of quantum key distribution (QKD) disregard the effect of information leakage from the users' devices, and, thus, do not protect against Trojan-horse attacks (THAs). In a THA, the eavesdropper injects strong light into the QKD apparatuses, and then analyzes the back-reflected light to learn information about their internal setting choices. Only a few recent works consider this… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.06630v1-abstract-full').style.display = 'inline'; document.getElementById('2202.06630v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.06630v1-abstract-full" style="display: none;"> Most security proofs of quantum key distribution (QKD) disregard the effect of information leakage from the users' devices, and, thus, do not protect against Trojan-horse attacks (THAs). In a THA, the eavesdropper injects strong light into the QKD apparatuses, and then analyzes the back-reflected light to learn information about their internal setting choices. Only a few recent works consider this security threat, but predict a rather poor performance of QKD unless the devices are strongly isolated from the channel. Here, we derive finite-key security bounds for decoy-state-based QKD schemes in the presence of THAs, which significantly outperform previous analyses. Our results constitute an important step forward to closing the existing gap between theory and practice in QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.06630v1-abstract-full').style.display = 'none'; document.getElementById('2202.06630v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 14 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 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">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> Quantum Science and Technology 7, 035021 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.12393">arXiv:2108.12393</a> <span> [<a href="https://arxiv.org/pdf/2108.12393">pdf</a>, <a href="https://arxiv.org/ps/2108.12393">ps</a>, <a href="https://arxiv.org/format/2108.12393">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.104.062417">10.1103/PhysRevA.104.062417 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Foiling zero-error attacks against coherent-one-way quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2108.12393v1-abstract-short" style="display: inline;"> To protect practical quantum key distribution (QKD) against photon-number-splitting attacks, one could measure the coherence of the received signals. One prominent example that follows this approach is coherent-one-way (COW) QKD, which is commercially available. Surprisingly, however, it has been shown very recently that its secret key rate scales quadratically with the channel transmittance, and,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12393v1-abstract-full').style.display = 'inline'; document.getElementById('2108.12393v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.12393v1-abstract-full" style="display: none;"> To protect practical quantum key distribution (QKD) against photon-number-splitting attacks, one could measure the coherence of the received signals. One prominent example that follows this approach is coherent-one-way (COW) QKD, which is commercially available. Surprisingly, however, it has been shown very recently that its secret key rate scales quadratically with the channel transmittance, and, thus, this scheme is unsuitable for long-distance transmission. This result was derived by using a zero-error attack, which prevents the distribution of a secure key without introducing any error. Here, we study various countermeasures to foil zero-error attacks against COW-QKD. They require to either monitor some additional available detection statistics, or to increase the number of quantum states emitted. We obtain asymptotic upper security bounds on the secret key rate that scale close to linear with the channel transmittance, thus suggesting the effectiveness of the countermeasures to boost the performance of this protocol. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.12393v1-abstract-full').style.display = 'none'; document.getElementById('2108.12393v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 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">Comments:</span> <span class="has-text-grey-dark mathjax">27 pages, 18 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 104, 062417 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2105.11165">arXiv:2105.11165</a> <span> [<a href="https://arxiv.org/pdf/2105.11165">pdf</a>, <a href="https://arxiv.org/format/2105.11165">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/10.22331/q-2021-12-07-602">10.22331/q-2021-12-07-602 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security of quantum key distribution with intensity correlations </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2105.11165v2-abstract-short" style="display: inline;"> The decoy-state method in quantum key distribution (QKD) is a popular technique to approximately achieve the performance of ideal single-photon sources by means of simpler and practical laser sources. In high-speed decoy-state QKD systems, however, intensity correlations between succeeding pulses leak information about the users' intensity settings, thus invalidating a key assumption of this appro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11165v2-abstract-full').style.display = 'inline'; document.getElementById('2105.11165v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2105.11165v2-abstract-full" style="display: none;"> The decoy-state method in quantum key distribution (QKD) is a popular technique to approximately achieve the performance of ideal single-photon sources by means of simpler and practical laser sources. In high-speed decoy-state QKD systems, however, intensity correlations between succeeding pulses leak information about the users' intensity settings, thus invalidating a key assumption of this approach. Here, we solve this pressing problem by developing a general technique to incorporate arbitrary intensity correlations to the security analysis of decoy-state QKD. This technique only requires to experimentally quantify two main parameters: the correlation range and the maximum relative deviation between the selected and the actually emitted intensities. As a side contribution, we provide a non-standard derivation of the asymptotic secret key rate formula from the non-asymptotic one, in so revealing a necessary condition for the significance of the former. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2105.11165v2-abstract-full').style.display = 'none'; document.getElementById('2105.11165v2-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 December, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 May, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">21 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum 5, 602 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2101.07192">arXiv:2101.07192</a> <span> [<a href="https://arxiv.org/pdf/2101.07192">pdf</a>, <a href="https://arxiv.org/format/2101.07192">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> </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/ac1e41">10.1088/1367-2630/ac1e41 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Zero-error attack against coherent-one-way quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tr%C3%A9nyi%2C+R">R贸bert Tr茅nyi</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2101.07192v1-abstract-short" style="display: inline;"> Coherent-one-way (COW) quantum key distribution (QKD) held the promise of distributing secret keys over long distances with a simple experimental setup. Indeed, this scheme is currently used in commercial applications. Surprisingly, however, it has been recently shown that its secret key rate scales at most quadratically with the system's transmittance and, thus, it is not appropriate for long dis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.07192v1-abstract-full').style.display = 'inline'; document.getElementById('2101.07192v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2101.07192v1-abstract-full" style="display: none;"> Coherent-one-way (COW) quantum key distribution (QKD) held the promise of distributing secret keys over long distances with a simple experimental setup. Indeed, this scheme is currently used in commercial applications. Surprisingly, however, it has been recently shown that its secret key rate scales at most quadratically with the system's transmittance and, thus, it is not appropriate for long distance QKD transmission. Such pessimistic result was derived by employing a so-called zero-error attack, in which the eavesdropper does not introduce any error, but still the legitimate users of the system cannot distill a secure key. Here, we present a zero-error attack against COW-QKD that is essentially optimal, in the sense that no other attack can restrict further its maximum achievable distance in the absence of errors. This translates into an upper bound on its secret key rate that is more than an order of magnitude lower than previously known upper bounds. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2101.07192v1-abstract-full').style.display = 'none'; document.getElementById('2101.07192v1-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 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 7 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, 093005 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.03364">arXiv:2007.03364</a> <span> [<a href="https://arxiv.org/pdf/2007.03364">pdf</a>, <a href="https://arxiv.org/format/2007.03364">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/PhysRevApplied.15.034072">10.1103/PhysRevApplied.15.034072 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Practical Quantum Key Distribution Secure Against Side-Channels </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.03364v2-abstract-short" style="display: inline;"> There is a big gap between theory and practice in quantum key distribution (QKD) because real devices do not satisfy the assumptions required by the security proofs. Here, we close this gap by introducing a simple and practical measurement-device-independent (MDI) QKD type of protocol, based on the transmission of coherent light, for which we prove its security against any possible device imperfec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.03364v2-abstract-full').style.display = 'inline'; document.getElementById('2007.03364v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.03364v2-abstract-full" style="display: none;"> There is a big gap between theory and practice in quantum key distribution (QKD) because real devices do not satisfy the assumptions required by the security proofs. Here, we close this gap by introducing a simple and practical measurement-device-independent (MDI) QKD type of protocol, based on the transmission of coherent light, for which we prove its security against any possible device imperfection and/or side-channel at the transmitters' side. Besides using a much simpler experimental set-up and source characterization with only one single parameter, we show that the performance of the protocol is comparable to other MDI-QKD type of protocols which disregard the effect of several side-channels. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.03364v2-abstract-full').style.display = 'none'; document.getElementById('2007.03364v2-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 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 4 figures. v2: results revised, typos corrected, appendix B extended</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 15, 034072 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.16891">arXiv:2006.16891</a> <span> [<a href="https://arxiv.org/pdf/2006.16891">pdf</a>, <a href="https://arxiv.org/format/2006.16891">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/PhysRevLett.125.260510">10.1103/PhysRevLett.125.260510 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Upper security bounds for coherent-one-way quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Gonz%C3%A1lez-Payo%2C+J">Javier Gonz谩lez-Payo</a>, <a href="/search/quant-ph?searchtype=author&query=Tr%C3%A9nyi%2C+R">R贸bert Tr茅nyi</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weilong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.16891v2-abstract-short" style="display: inline;"> The performance of quantum key distribution (QKD) is severely limited by multi-photon pulses emitted by laser sources due to the photon-number splitting attack. Coherent-one-way (COW) QKD has been introduced as a promising solution to overcome this limitation, and thus extend the achievable distance of practical QKD. Indeed, thanks to its experimental simplicity, the COW protocol is already used i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.16891v2-abstract-full').style.display = 'inline'; document.getElementById('2006.16891v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.16891v2-abstract-full" style="display: none;"> The performance of quantum key distribution (QKD) is severely limited by multi-photon pulses emitted by laser sources due to the photon-number splitting attack. Coherent-one-way (COW) QKD has been introduced as a promising solution to overcome this limitation, and thus extend the achievable distance of practical QKD. Indeed, thanks to its experimental simplicity, the COW protocol is already used in commercial applications. Here, we derive simple upper security bounds on its secret key rate, which demonstrate that it scales at most quadratically with the system's transmittance, thus solving a long-standing problem. That is, in contrast to what has been claimed, this approach is inappropriate for long-distance QKD transmission. Remarkably, our findings imply that all implementations of the COW protocol performed so far are insecure. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.16891v2-abstract-full').style.display = 'none'; document.getElementById('2006.16891v2-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 January, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 30 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 pages, 3 figures, supplementary materials included as ancillary file; close 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. Lett. 125, 260510 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2006.14337">arXiv:2006.14337</a> <span> [<a href="https://arxiv.org/pdf/2006.14337">pdf</a>, <a href="https://arxiv.org/format/2006.14337">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/s41534-020-00358-y">10.1038/s41534-020-00358-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Secure quantum key distribution with a subset of malicious devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.14337v2-abstract-short" style="display: inline;"> The malicious manipulation of quantum key distribution (QKD) hardware is a serious threat to its security, as, typically, neither end users nor QKD manufacturers can validate the integrity of every component of their QKD system in practice. One possible approach to re-establish the security of QKD is to use a redundant number of devices. Following this idea, we introduce an efficient distributed Q… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.14337v2-abstract-full').style.display = 'inline'; document.getElementById('2006.14337v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.14337v2-abstract-full" style="display: none;"> The malicious manipulation of quantum key distribution (QKD) hardware is a serious threat to its security, as, typically, neither end users nor QKD manufacturers can validate the integrity of every component of their QKD system in practice. One possible approach to re-establish the security of QKD is to use a redundant number of devices. Following this idea, we introduce an efficient distributed QKD post-processing protocol and prove its security in a variety of corruption models of the possibly malicious devices. We find that, compared to the most conservative model of active and collaborative corrupted devices, natural assumptions lead to a significant enhancement of the secret key rate and considerably simpler QKD setups. Furthermore, we show that, for most practical situations, the resulting finite-size secret key rate is similar to that of the standard scenario assuming trusted devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.14337v2-abstract-full').style.display = 'none'; document.getElementById('2006.14337v2-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 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">35 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 7, 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/2006.12863">arXiv:2006.12863</a> <span> [<a href="https://arxiv.org/pdf/2006.12863">pdf</a>, <a href="https://arxiv.org/format/2006.12863">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/PhysRevApplied.15.034081">10.1103/PhysRevApplied.15.034081 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental quantum key distribution secure against malicious devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+W">Wei Li</a>, <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">Victor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Tan%2C+H">Hao Tan</a>, <a href="/search/quant-ph?searchtype=author&query=Wei%2C+K">Kejin Wei</a>, <a href="/search/quant-ph?searchtype=author&query=Min%2C+H">Hao Min</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+W">Wei-Yue Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Liao%2C+S">Sheng-Kai Liao</a>, <a href="/search/quant-ph?searchtype=author&query=Peng%2C+C">Cheng-Zhi Peng</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2006.12863v1-abstract-short" style="display: inline;"> The fabrication of quantum key distribution (QKD) systems typically involves several parties, thus providing Eve with multiple opportunities to meddle with the devices. As a consequence, conventional hardware and/or software hacking attacks pose natural threats to the security of practical QKD. Fortunately, if the number of corrupted devices is limited, the security can be restored by using redund… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.12863v1-abstract-full').style.display = 'inline'; document.getElementById('2006.12863v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2006.12863v1-abstract-full" style="display: none;"> The fabrication of quantum key distribution (QKD) systems typically involves several parties, thus providing Eve with multiple opportunities to meddle with the devices. As a consequence, conventional hardware and/or software hacking attacks pose natural threats to the security of practical QKD. Fortunately, if the number of corrupted devices is limited, the security can be restored by using redundant apparatuses. Here, we report on the demonstration of a secure QKD setup with optical devices and classical post-processing units possibly controlled by an eavesdropper. We implement a 1.25 GHz chip-based measurement-device-independent QKD system secure against malicious devices on \emph{both} the measurement and the users' sides. The secret key rate reaches 137 bps over a 24 dB channel loss. Our setup, benefiting from high clock rate, miniaturized transmitters and a cost-effective structure, provides a promising solution for widespread applications requiring uncompromising communication security. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2006.12863v1-abstract-full').style.display = 'none'; document.getElementById('2006.12863v1-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 June, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">28 pages, 5 figures, 4 tables</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 15, 034081 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2001.08086">arXiv:2001.08086</a> <span> [<a href="https://arxiv.org/pdf/2001.08086">pdf</a>, <a href="https://arxiv.org/format/2001.08086">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/s41598-021-81003-2">10.1038/s41598-021-81003-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-Device-Independent Quantum Key Distribution with Leaky Sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weilong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="2001.08086v1-abstract-short" style="display: inline;"> Measurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This includes, for instance, the requirement that there is no information leakage from the transmitters of the senders, which unfortunately is very difficult to guara… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08086v1-abstract-full').style.display = 'inline'; document.getElementById('2001.08086v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2001.08086v1-abstract-full" style="display: none;"> Measurement-device-independent quantum key distribution (MDI-QKD) can remove all detection side-channels from quantum communication systems. The security proofs require, however, that certain assumptions on the sources are satisfied. This includes, for instance, the requirement that there is no information leakage from the transmitters of the senders, which unfortunately is very difficult to guarantee in practice. In this paper we relax this unrealistic assumption by presenting a general formalism to prove the security of MDI-QKD with leaky sources. With this formalism, we analyze the finite-key security of two prominent MDI-QKD schemes - a symmetric three-intensity decoy-state MDI-QKD protocol and a four-intensity decoy-state MDI-QKD protocol - and determine their robustness against information leakage from both the intensity modulator and the phase modulator of the transmitters. Our work shows that MDI-QKD is feasible within a reasonable time frame of signal transmission given that the sources are sufficiently isolated. Thus, it provides an essential reference for experimentalists to ensure the security of experimental implementations of MDI-QKD in the presence of information leakage. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2001.08086v1-abstract-full').style.display = 'none'; document.getElementById('2001.08086v1-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 January, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 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">46 pages, 11 figures. arXiv admin note: text overlap with arXiv:1803.09508</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports, (2021) 11:1678 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1910.11407">arXiv:1910.11407</a> <span> [<a href="https://arxiv.org/pdf/1910.11407">pdf</a>, <a href="https://arxiv.org/format/1910.11407">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/s41534-020-00345-3">10.1038/s41534-020-00345-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tight finite-key security for twin-field quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curr%C3%A1s-Lorenzo%2C+G">Guillermo Curr谩s-Lorenzo</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+A">Alvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Azuma%2C+K">Koji Azuma</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Razavi%2C+M">Mohsen Razavi</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="1910.11407v4-abstract-short" style="display: inline;"> Quantum key distribution (QKD) offers a reliable solution to communication problems that require long-term data security. For its widespread use, however, the rate and reach of QKD systems must be improved. Twin-field (TF) QKD is a step forward toward this direction, with early demonstrations suggesting it can beat the current rate-versus-distance records. A recently introduced variant of TF-QKD i… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.11407v4-abstract-full').style.display = 'inline'; document.getElementById('1910.11407v4-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1910.11407v4-abstract-full" style="display: none;"> Quantum key distribution (QKD) offers a reliable solution to communication problems that require long-term data security. For its widespread use, however, the rate and reach of QKD systems must be improved. Twin-field (TF) QKD is a step forward toward this direction, with early demonstrations suggesting it can beat the current rate-versus-distance records. A recently introduced variant of TF-QKD is particularly suited for experimental implementation, and has been shown to offer a higher key rate than other variants in the asymptotic regime where users exchange an infinite number of signals. Here, we extend the security of this protocol to the finite-key regime, showing that it can overcome the fundamental bounds on point-to-point QKD with around $10^{10}$ transmitted signals. Within distance regimes of interest, our analysis offers higher key rates than those of alternative variants. Moreover, some of the techniques we develop are applicable to the finite-key analysis of other QKD protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1910.11407v4-abstract-full').style.display = 'none'; document.getElementById('1910.11407v4-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 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 October, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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, 5 figures. v2: major changes on subsection "Concentration inequality for sums of dependent random variables", minor changes elsewhere. v3: Changes on subsection "Concentration inequality for sums of dependent random variables", to use the newest version of the inequality in Ref. [38]. Minor changes in citations elsewhere. v4: Fixed wrong citation numbers in graph legends</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 7, 22 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.08261">arXiv:1908.08261</a> <span> [<a href="https://arxiv.org/pdf/1908.08261">pdf</a>, <a href="https://arxiv.org/format/1908.08261">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/10.1126/sciadv.aaz4487">10.1126/sciadv.aaz4487 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum key distribution with correlated sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1908.08261v5-abstract-short" style="display: inline;"> In theory, quantum key distribution (QKD) offers information-theoretic security. In practice, however, it does not due to the discrepancies between the assumptions used in the security proofs and the behaviour of the real apparatuses. Recent years have witnessed a tremendous effort to fill the gap, but the treatment of correlations among pulses has remained a major elusive problem. Here, we close… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.08261v5-abstract-full').style.display = 'inline'; document.getElementById('1908.08261v5-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.08261v5-abstract-full" style="display: none;"> In theory, quantum key distribution (QKD) offers information-theoretic security. In practice, however, it does not due to the discrepancies between the assumptions used in the security proofs and the behaviour of the real apparatuses. Recent years have witnessed a tremendous effort to fill the gap, but the treatment of correlations among pulses has remained a major elusive problem. Here, we close this gap by introducing a simple yet general method to prove the security of QKD with arbitrarily long-range pulse correlations. Our method is compatible with those security proofs that accommodate all the other typical device imperfections, thus paving the way towards achieving implementation security in QKD with arbitrary flawed devices. Moreover, we introduce a new framework for security proofs, which we call the reference technique. This framework includes existing security proofs as special cases and it can be widely applied to a number of QKD protocols. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.08261v5-abstract-full').style.display = 'none'; document.getElementById('1908.08261v5-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 March, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 22 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">Journal ref:</span> Science Advances 6, no. 37, eaaz4487 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1908.04539">arXiv:1908.04539</a> <span> [<a href="https://arxiv.org/pdf/1908.04539">pdf</a>, <a href="https://arxiv.org/format/1908.04539">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/ab54aa">10.1088/1367-2630/ab54aa <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Beating the repeaterless bound with adaptive measurement-device-independent quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tr%C3%A9nyi%2C+R">R贸bert Tr茅nyi</a>, <a href="/search/quant-ph?searchtype=author&query=Azuma%2C+K">Koji Azuma</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1908.04539v1-abstract-short" style="display: inline;"> Surpassing the repeaterless bound is a crucial task on the way towards realizing long-distance quantum key distribution. In this paper, we focus on the protocol proposed by Azuma et al. in [Nature Communications 6, 10171 (2015)], which can beat this bound with idealized devices. We investigate the robustness of this protocol against imperfections in realistic setups, particularly the multiple-phot… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.04539v1-abstract-full').style.display = 'inline'; document.getElementById('1908.04539v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1908.04539v1-abstract-full" style="display: none;"> Surpassing the repeaterless bound is a crucial task on the way towards realizing long-distance quantum key distribution. In this paper, we focus on the protocol proposed by Azuma et al. in [Nature Communications 6, 10171 (2015)], which can beat this bound with idealized devices. We investigate the robustness of this protocol against imperfections in realistic setups, particularly the multiple-photon pair components emitted by practical entanglement sources. In doing so, we derive necessary conditions on the photon-number statistics of the sources in order to beat the repeaterless bound. We show, for instance, that parametric down-conversion sources do not satisfy the required conditions and thus cannot be used to outperform this bound. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1908.04539v1-abstract-full').style.display = 'none'; document.getElementById('1908.04539v1-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 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">21 pages, 8 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. 21, 113052 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1907.05256">arXiv:1907.05256</a> <span> [<a href="https://arxiv.org/pdf/1907.05256">pdf</a>, <a href="https://arxiv.org/format/1907.05256">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/ab520e">10.1088/1367-2630/ab520e <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Asymmetric twin-field quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Grasselli%2C+F">Federico Grasselli</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+A">Alvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="1907.05256v1-abstract-short" style="display: inline;"> Twin-Field (TF) quantum key distribution (QKD) is a major candidate to be the new benchmark for far-distance QKD implementations, since its secret key rate can overcome the repeaterless bound by means of a simple interferometric measurement. Many variants of the original protocol have been recently proven to be secure. Here, we focus on the TF-QKD type protocol proposed by Curty et al [preprint ar… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.05256v1-abstract-full').style.display = 'inline'; document.getElementById('1907.05256v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1907.05256v1-abstract-full" style="display: none;"> Twin-Field (TF) quantum key distribution (QKD) is a major candidate to be the new benchmark for far-distance QKD implementations, since its secret key rate can overcome the repeaterless bound by means of a simple interferometric measurement. Many variants of the original protocol have been recently proven to be secure. Here, we focus on the TF-QKD type protocol proposed by Curty et al [preprint arXiv:1807.07667], which can provide a high secret key rate and whose practical feasibility has been demonstrated in various recent experiments. The security of this protocol relies on the estimation of certain detection probabilities (yields) through the decoy-state technique. Analytical bounds on the relevant yields have been recently derived assuming that both parties use the same set of decoy intensities, thus providing sub-optimal key rates in asymmetric-loss scenarios. Here we derive new analytical bounds when the parties use either three or four independent decoy intensity settings each. With the new bounds we optimize the protocol's performance in asymmetric-loss scenarios and show that the protocol is robust against uncorrelated intensity fluctuations affecting the parties' lasers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1907.05256v1-abstract-full').style.display = 'none'; document.getElementById('1907.05256v1-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, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">30 pages, 8 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. 21 113032 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1905.03591">arXiv:1905.03591</a> <span> [<a href="https://arxiv.org/pdf/1905.03591">pdf</a>, <a href="https://arxiv.org/format/1905.03591">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/s41598-019-53803-0">10.1038/s41598-019-53803-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Long-distance device-independent quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zapatero%2C+V">V铆ctor Zapatero</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1905.03591v1-abstract-short" style="display: inline;"> Besides being a beautiful idea, device-independent quantum key distribution (DIQKD) is probably the ultimate solution to defeat quantum hacking. To guarantee security, it requires, however, that the fair-sampling loophole is closed, which results in a very limited maximum achievable distance. To overcome this limitation, DIQKD must be furnished with fair-sampling devices like, for instance, qubit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.03591v1-abstract-full').style.display = 'inline'; document.getElementById('1905.03591v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1905.03591v1-abstract-full" style="display: none;"> Besides being a beautiful idea, device-independent quantum key distribution (DIQKD) is probably the ultimate solution to defeat quantum hacking. To guarantee security, it requires, however, that the fair-sampling loophole is closed, which results in a very limited maximum achievable distance. To overcome this limitation, DIQKD must be furnished with fair-sampling devices like, for instance, qubit amplifiers. These devices can herald the arrival of a photon to the receiver and thus decouple channel loss from the selection of the measurement settings. Consequently, one can safely postselect the heralded events and discard the rest, which results in a significant enhancement of the achievable distance. In this work, we investigate photonic-based DIQKD assisted by two main types of qubit amplifiers in the finite data block size scenario, and study the resources -- particularly, the detection efficiency of the photodetectors and the quality of the entanglement sources -- that would be necessary to achieve long-distance DIQKD within a reasonable time frame of signal transmission. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1905.03591v1-abstract-full').style.display = 'none'; document.getElementById('1905.03591v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">37 pages, 15 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports 9, 17749 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.10209">arXiv:1902.10209</a> <span> [<a href="https://arxiv.org/pdf/1902.10209">pdf</a>, <a href="https://arxiv.org/format/1902.10209">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/PhysRevLett.123.100506">10.1103/PhysRevLett.123.100506 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Proof-of-principle experimental demonstration of twin-field type quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Zhong%2C+X">X. Zhong</a>, <a href="/search/quant-ph?searchtype=author&query=Hu%2C+J">J. Hu</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">M. Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">L. Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H+-">H. -K. Lo</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="1902.10209v1-abstract-short" style="display: inline;"> The twin-field (TF) quantum key distribution (QKD) protocol and its variants are highly attractive because they can beat the well-known rate-loss limit (i.e., the PLOB bound) for QKD protocols without quantum repeaters. In this paper, we perform a proof-of-principle experimental demonstration of TF-QKD based on the protocol proposed by Curty et al. which removes from the original TF-QKD scheme the… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10209v1-abstract-full').style.display = 'inline'; document.getElementById('1902.10209v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.10209v1-abstract-full" style="display: none;"> The twin-field (TF) quantum key distribution (QKD) protocol and its variants are highly attractive because they can beat the well-known rate-loss limit (i.e., the PLOB bound) for QKD protocols without quantum repeaters. In this paper, we perform a proof-of-principle experimental demonstration of TF-QKD based on the protocol proposed by Curty et al. which removes from the original TF-QKD scheme the need for post-selection on the matching of a global phase, and can deliver nearly an order of magnitude higher secret key rate. Furthermore, we overcome the major difficulty in the practical implementation of TF-QKD, namely, the need to stabilize the phase of the quantum state over kilometers of fiber. A Sagnac loop structure is utilized to ensure excellent phase stability between the different parties. Using decoy states, we demonstrate secret-key generation rates that beat the PLOB bound when the channel loss is above 40 dB. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10209v1-abstract-full').style.display = 'none'; document.getElementById('1902.10209v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 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">7 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 123, 100506 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.10034">arXiv:1902.10034</a> <span> [<a href="https://arxiv.org/pdf/1902.10034">pdf</a>, <a href="https://arxiv.org/format/1902.10034">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/ab2b00">10.1088/1367-2630/ab2b00 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Practical decoy-state method for twin-field quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Grasselli%2C+F">Federico Grasselli</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="1902.10034v2-abstract-short" style="display: inline;"> Twin-Field (TF) quantum key distribution (QKD) represents a novel QKD approach whose principal merit is to beat the point-to-point private capacity of a lossy quantum channel, thanks to performing single-photon interference in an untrusted node. Indeed, recent security proofs of various TF-QKD type protocols have confirmed that the secret key rate of these schemes scales essentially as the square… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10034v2-abstract-full').style.display = 'inline'; document.getElementById('1902.10034v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.10034v2-abstract-full" style="display: none;"> Twin-Field (TF) quantum key distribution (QKD) represents a novel QKD approach whose principal merit is to beat the point-to-point private capacity of a lossy quantum channel, thanks to performing single-photon interference in an untrusted node. Indeed, recent security proofs of various TF-QKD type protocols have confirmed that the secret key rate of these schemes scales essentially as the square root of the transmittance of the channel. Here, we focus on the TF-QKD protocol introduced by Curty et al, whose secret key rate is nearly an order of magnitude higher than previous solutions. Its security relies on the estimation of the detection probabilities associated to various photon-number states through the decoy-state method. We derive analytical bounds on these quantities assuming that each party uses either two, three or four decoy intensity settings, and we investigate the protocol's performance in this scenario. Our simulations show that two decoy intensity settings are enough to beat the point-to-point private capacity of the channel, and that the use of four decoys is already basically optimal, in the sense that it almost reproduces the ideal scenario of infinite decoys. We also observe that the protocol seems to be quite robust against intensity fluctuations of the optical pulses prepared by the parties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.10034v2-abstract-full').style.display = 'none'; document.getElementById('1902.10034v2-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 June, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">37 pages, 15 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. 21, 073001 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.09792">arXiv:1902.09792</a> <span> [<a href="https://arxiv.org/pdf/1902.09792">pdf</a>, <a href="https://arxiv.org/format/1902.09792">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/PhysRevApplied.12.064043">10.1103/PhysRevApplied.12.064043 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Laser seeding attack in quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Huang%2C+A">Anqi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shi-Hai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Chaiwongkhot%2C+P">Poompong Chaiwongkhot</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Makarov%2C+V">Vadim Makarov</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="1902.09792v3-abstract-short" style="display: inline;"> Quantum key distribution (QKD) based on the laws of quantum physics allows the secure distribution of secret keys over an insecure channel. Unfortunately, imperfect implementations of QKD compromise its information-theoretical security. Measurement-device-independent quantum key distribution (MDI-QKD) is a promising approach to remove all side channels from the measurement unit, which is regarded… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.09792v3-abstract-full').style.display = 'inline'; document.getElementById('1902.09792v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.09792v3-abstract-full" style="display: none;"> Quantum key distribution (QKD) based on the laws of quantum physics allows the secure distribution of secret keys over an insecure channel. Unfortunately, imperfect implementations of QKD compromise its information-theoretical security. Measurement-device-independent quantum key distribution (MDI-QKD) is a promising approach to remove all side channels from the measurement unit, which is regarded as the "Achilles' heel" of QKD. An essential assumption in MDI-QKD is however that the sources are trusted. Here we experimentally demonstrate that a practical source based on a semiconductor laser diode is vulnerable to a laser seeding attack, in which light injected from the communication line into the laser results in an increase of the intensities of the prepared states. The unnoticed increase of intensity may compromise the security of QKD, as we show theoretically for the prepare-and-measure decoy-state BB84 and MDI-QKD protocols. Our theoretical security analysis is general and can be applied to any vulnerability that increases the intensity of the emitted pulses. Moreover, a laser seeding attack might be launched as well against decoy-state based quantum cryptographic protocols beyond QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.09792v3-abstract-full').style.display = 'none'; document.getElementById('1902.09792v3-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 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">14 pages, 7 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Applied 12, 064043 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1902.02126">arXiv:1902.02126</a> <span> [<a href="https://arxiv.org/pdf/1902.02126">pdf</a>, <a href="https://arxiv.org/format/1902.02126">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"> Quantum key distribution with flawed and leaky sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Pereira%2C+M">Margarida Pereira</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</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="1902.02126v2-abstract-short" style="display: inline;"> In theory, quantum key distribution (QKD) allows secure communications between two parties based on physical laws. However, most of the security proofs of QKD today make unrealistic assumptions and neglect many relevant device imperfections. As a result, they cannot guarantee the security of the practical implementations. Recently, the loss-tolerant protocol (K. Tamaki et al, Phys. Rev. A, 90, 052… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.02126v2-abstract-full').style.display = 'inline'; document.getElementById('1902.02126v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1902.02126v2-abstract-full" style="display: none;"> In theory, quantum key distribution (QKD) allows secure communications between two parties based on physical laws. However, most of the security proofs of QKD today make unrealistic assumptions and neglect many relevant device imperfections. As a result, they cannot guarantee the security of the practical implementations. Recently, the loss-tolerant protocol (K. Tamaki et al, Phys. Rev. A, 90, 052314, 2014) was proposed to make QKD robust against state preparation flaws. This protocol relies on the emission of qubit systems which, unfortunately, is difficult to achieve in practice. In this work, we remove such qubit assumption and generalise the loss-tolerant protocol to accommodate multiple optical modes in the emitted signals. These multiple optical modes could arise, for example, from Trojan horse attacks and/or device imperfections. Our security proof determines some dominant device parameter regimes needed for achieving secure communication, and therefore it can serve as a guideline to characterise QKD transmitters. Furthermore, we compare our approach with that of Lo and Preskill (H.-K. Lo et al, Quantum Inf. Comput., 7, 431-458, 2007) and identify which method provides the highest secret key generation rate as a function of the device imperfections. Our work constitutes an important step towards the best practical and secure implementation for QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1902.02126v2-abstract-full').style.display = 'none'; document.getElementById('1902.02126v2-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 July, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 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">Journal ref:</span> npj Quantum Information 5, 62 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1808.08259">arXiv:1808.08259</a> <span> [<a href="https://arxiv.org/pdf/1808.08259">pdf</a>, <a href="https://arxiv.org/format/1808.08259">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.98.052336">10.1103/PhysRevA.98.052336 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security proof for a simplified BB84-like QKD protocol </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Rusca%2C+D">Davide Rusca</a>, <a href="/search/quant-ph?searchtype=author&query=Boaron%2C+A">Alberto Boaron</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Martin%2C+A">Anthony Martin</a>, <a href="/search/quant-ph?searchtype=author&query=Zbinden%2C+H">Hugo Zbinden</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="1808.08259v2-abstract-short" style="display: inline;"> The security of quantum key distribution (QKD) has been proven for different protocols, in particular for the BB84 protocol. It has been shown that this scheme is robust against eventual imperfections in the state preparation, and sending only three different states delivers the same secret key rate achievable with four states. In this work, we prove, in a finite-key scenario, that the security of… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.08259v2-abstract-full').style.display = 'inline'; document.getElementById('1808.08259v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1808.08259v2-abstract-full" style="display: none;"> The security of quantum key distribution (QKD) has been proven for different protocols, in particular for the BB84 protocol. It has been shown that this scheme is robust against eventual imperfections in the state preparation, and sending only three different states delivers the same secret key rate achievable with four states. In this work, we prove, in a finite-key scenario, that the security of this protocol can be maintained even with less measurement operators on the receiver. This allows us to implement a time-bin encoding scheme with a minimum amount of resources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1808.08259v2-abstract-full').style.display = 'none'; document.getElementById('1808.08259v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 August, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 98, 052336 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.07667">arXiv:1807.07667</a> <span> [<a href="https://arxiv.org/pdf/1807.07667">pdf</a>, <a href="https://arxiv.org/format/1807.07667">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"> Simple security proof of twin-field type quantum key distribution protocol </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Azuma%2C+K">Koji Azuma</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1807.07667v2-abstract-short" style="display: inline;"> Twin-field (TF) quantum key distribution (QKD) was conjectured to beat the private capacity of a point-to-point QKD link by using single-photon interference in a central measuring station. This remarkable conjecture has recently triggered an intense research activity to prove its security. Here, we introduce a TF-type QKD protocol which is conceptually simpler than the original proposal. It relies… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.07667v2-abstract-full').style.display = 'inline'; document.getElementById('1807.07667v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.07667v2-abstract-full" style="display: none;"> Twin-field (TF) quantum key distribution (QKD) was conjectured to beat the private capacity of a point-to-point QKD link by using single-photon interference in a central measuring station. This remarkable conjecture has recently triggered an intense research activity to prove its security. Here, we introduce a TF-type QKD protocol which is conceptually simpler than the original proposal. It relies on local phase randomization, instead of global phase randomization, which significantly simplifies its security analysis and is arguably less demanding experimentally. We demonstrate that the secure key rate of our protocol has a square-root improvement over the point-to-point private capacity, as conjectured by the original TF-QKD scheme. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.07667v2-abstract-full').style.display = 'none'; document.getElementById('1807.07667v2-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 19 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">11 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 5, 64 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1807.04377">arXiv:1807.04377</a> <span> [<a href="https://arxiv.org/pdf/1807.04377">pdf</a>, <a href="https://arxiv.org/format/1807.04377">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.98.042324">10.1103/PhysRevA.98.042324 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Secure quantum communication in the presence of phase and polarization dependent loss </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Li%2C+C">Chenyang Li</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Bedroya%2C+O">Olinka Bedroya</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1807.04377v3-abstract-short" style="display: inline;"> Silicon photonics holds the promise of the miniaturization of quantum communication devices. Recently, silicon chip optical transmitters for quantum key distribution (QKD) have been built and demonstrated experimentally. Nonetheless, these silicon chips suffer substantial polarization and phase dependent loss which, if unchecked, could compromise the security of QKD systems. Here, we first restore… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.04377v3-abstract-full').style.display = 'inline'; document.getElementById('1807.04377v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1807.04377v3-abstract-full" style="display: none;"> Silicon photonics holds the promise of the miniaturization of quantum communication devices. Recently, silicon chip optical transmitters for quantum key distribution (QKD) have been built and demonstrated experimentally. Nonetheless, these silicon chips suffer substantial polarization and phase dependent loss which, if unchecked, could compromise the security of QKD systems. Here, we first restore the security by regarding the single photons without phase and polarization dependence as untagged and secure qubits. Next, by using a post-selection technique, one could implement a secure QKD protocol that provides a high key generation rate even in the presence of severe phase and polarization dependent loss. Our solution is simple to realize in a practical experiment as it does not require any hardware modification. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1807.04377v3-abstract-full').style.display = 'none'; document.getElementById('1807.04377v3-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, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 July, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">10 pages, 7 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 98, 042324 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.09508">arXiv:1803.09508</a> <span> [<a href="https://arxiv.org/pdf/1803.09508">pdf</a>, <a href="https://arxiv.org/format/1803.09508">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/aad839">10.1088/1367-2630/aad839 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Finite-key security analysis for quantum key distribution with leaky sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Weilong Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.09508v1-abstract-short" style="display: inline;"> Security proofs of quantum key distribution (QKD) typically assume that the devices of the legitimate users are perfectly shielded from the eavesdropper. This assumption is, however, very hard to meet in practice, and thus the security of current QKD implementations is not guaranteed. Here, we fill this gap by providing a finite-key security analysis for QKD which is valid against arbitrary inform… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.09508v1-abstract-full').style.display = 'inline'; document.getElementById('1803.09508v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.09508v1-abstract-full" style="display: none;"> Security proofs of quantum key distribution (QKD) typically assume that the devices of the legitimate users are perfectly shielded from the eavesdropper. This assumption is, however, very hard to meet in practice, and thus the security of current QKD implementations is not guaranteed. Here, we fill this gap by providing a finite-key security analysis for QKD which is valid against arbitrary information leakage from the state preparation process of the legitimate users. For this, we extend the techniques introduced in (New J. Phys. 18, 065008, (2016)) to the finite-key regime, and we evaluate the security of a leaky decoy-state BB84 protocol with biased basis choice, which is one of the most implemented QKD schemes today. Our simulation results demonstrate the practicability of QKD over long distances and within a reasonable time frame given that the legitimate users' devices are sufficiently isolated. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.09508v1-abstract-full').style.display = 'none'; document.getElementById('1803.09508v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 5 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. 20 083027 2018 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.09484">arXiv:1803.09484</a> <span> [<a href="https://arxiv.org/pdf/1803.09484">pdf</a>, <a href="https://arxiv.org/format/1803.09484">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/s41534-018-0122-y">10.1038/s41534-018-0122-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Quantum key distribution with setting-choice-independently correlated light sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Azuma%2C+K">Koji Azuma</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Ikuta%2C+R">Rikizo Ikuta</a>, <a href="/search/quant-ph?searchtype=author&query=Yamamoto%2C+T">Takashi Yamamoto</a>, <a href="/search/quant-ph?searchtype=author&query=Imoto%2C+N">Nobuyuki Imoto</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.09484v1-abstract-short" style="display: inline;"> Despite the enormous theoretical and experimental progress made so far in quantum key distribution (QKD), the security of most existing QKD implementations is not rigorously established yet. A critical obstacle is that almost all existing security proofs make ideal assumptions on the QKD devices. Problematically, such assumptions are hard to satisfy in the experiments, and therefore it is not obvi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.09484v1-abstract-full').style.display = 'inline'; document.getElementById('1803.09484v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.09484v1-abstract-full" style="display: none;"> Despite the enormous theoretical and experimental progress made so far in quantum key distribution (QKD), the security of most existing QKD implementations is not rigorously established yet. A critical obstacle is that almost all existing security proofs make ideal assumptions on the QKD devices. Problematically, such assumptions are hard to satisfy in the experiments, and therefore it is not obvious how to apply such security proofs to practical QKD systems. Fortunately, any imperfections and security-loopholes in the measurement devices can be perfectly closed by measurement-device-independent QKD (MDI-QKD), and thus we only need to consider how to secure the source devices. Among imperfections in the source devices, correlations between the sending pulses are one of the principal problems. In this paper, we consider a setting-choice-independent correlation (SCIC) framework in which the sending pulses can present arbitrary correlations but they are independent of the previous setting choices such as the bit, the basis and the intensity settings. Within the framework of SCIC, we consider the dominant fluctuations of the sending states, such as the relative phases and the intensities, and provide a self-contained information theoretic security proof for the loss-tolerant QKD protocol in the finite-key regime. We demonstrate the feasibility of secure quantum communication within a reasonable number of pulses sent, and thus we are convinced that our work constitutes a crucial step toward guaranteeing implementation security of QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.09484v1-abstract-full').style.display = 'none'; document.getElementById('1803.09484v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 26 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">27 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 5, 8 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1803.06045">arXiv:1803.06045</a> <span> [<a href="https://arxiv.org/pdf/1803.06045">pdf</a>, <a href="https://arxiv.org/format/1803.06045">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/10.1088/1367-2630/18/6/065008">10.1088/1367-2630/18/6/065008 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Decoy-state quantum key distribution with a leaky source </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Lucamarini%2C+M">Marco Lucamarini</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1803.06045v1-abstract-short" style="display: inline;"> In recent years, there has been a great effort to prove the security of quantum key distribution (QKD) with a minimum number of assumptions. Besides its intrinsic theoretical interest, this would allow for larger tolerance against device imperfections in the actual implementations. However, even in this device-independent scenario, one assumption seems unavoidable, that is, the presence of a prote… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.06045v1-abstract-full').style.display = 'inline'; document.getElementById('1803.06045v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1803.06045v1-abstract-full" style="display: none;"> In recent years, there has been a great effort to prove the security of quantum key distribution (QKD) with a minimum number of assumptions. Besides its intrinsic theoretical interest, this would allow for larger tolerance against device imperfections in the actual implementations. However, even in this device-independent scenario, one assumption seems unavoidable, that is, the presence of a protected space devoid of any unwanted information leakage in which the legitimate parties can privately generate, process and store their classical data. In this paper we relax this unrealistic and hardly feasible assumption and introduce a general formalism to tackle the information leakage problem in most of existing QKD systems. More specifically, we prove the security of optical QKD systems using phase and intensity modulators in their transmitters, which leak the setting information in an arbitrary manner. We apply our security proof to cases of practical interest and show key rates similar to those obtained in a perfectly shielded environment. Our work constitutes a fundamental step forward in guaranteeing implementation security of quantum communication systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1803.06045v1-abstract-full').style.display = 'none'; document.getElementById('1803.06045v1-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 March, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">37 pages, 5 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. 18, 065008 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.08724">arXiv:1711.08724</a> <span> [<a href="https://arxiv.org/pdf/1711.08724">pdf</a>, <a href="https://arxiv.org/format/1711.08724">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"> Foiling covert channels and malicious classical post-processing units in quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1711.08724v1-abstract-short" style="display: inline;"> Existing security proofs of quantum key distribution (QKD) suffer from two fundamental weaknesses. First, memory attacks have emerged as an important threat to the security of even device-independent quantum key distribution (DI-QKD), whenever QKD devices are re-used. This type of attacks constitutes an example of covert channels, which have attracted a lot of attention in security research in con… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.08724v1-abstract-full').style.display = 'inline'; document.getElementById('1711.08724v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.08724v1-abstract-full" style="display: none;"> Existing security proofs of quantum key distribution (QKD) suffer from two fundamental weaknesses. First, memory attacks have emerged as an important threat to the security of even device-independent quantum key distribution (DI-QKD), whenever QKD devices are re-used. This type of attacks constitutes an example of covert channels, which have attracted a lot of attention in security research in conventional cryptographic and communication systems. Second, it is often implicitly assumed that the classical post-processing units of a QKD system are trusted. This is a rather strong assumption and is very hard to justify in practice. Here, we propose a simple solution to these two fundamental problems. Specifically, we show that by using verifiable secret sharing and multiple optical devices and classical post-processing units, one could re-establish the security of QKD. Our techniques are rather general and they apply to both DI-QKD and non-DI-QKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.08724v1-abstract-full').style.display = 'none'; document.getElementById('1711.08724v1-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, 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">16 pages, 8 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> npj Quantum Information 5, 14 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1710.08495">arXiv:1710.08495</a> <span> [<a href="https://arxiv.org/pdf/1710.08495">pdf</a>, <a href="https://arxiv.org/format/1710.08495">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/aab746">10.1088/1367-2630/aab746 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Characterizing multi-photon quantum interference with practical light sources and threshold single-photon detectors </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Navarrete%2C+%C3%81">脕lvaro Navarrete</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wenyuan Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="1710.08495v1-abstract-short" style="display: inline;"> The experimental characterization of multi-photon quantum interference effects in optical networks is essential in many applications of photonic quantum technologies, which include quantum computing and quantum communication as two prominent examples. However, such characterization often requires technologies which are beyond our current experimental capabilities, and today's methods suffer from e… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.08495v1-abstract-full').style.display = 'inline'; document.getElementById('1710.08495v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1710.08495v1-abstract-full" style="display: none;"> The experimental characterization of multi-photon quantum interference effects in optical networks is essential in many applications of photonic quantum technologies, which include quantum computing and quantum communication as two prominent examples. However, such characterization often requires technologies which are beyond our current experimental capabilities, and today's methods suffer from errors due to the use of imperfect sources and photodetectors. In this paper, we introduce a simple experimental technique to characterise multi-photon quantum interference by means of practical laser sources and threshold single-photon detectors. Our technique is based on well-known methods in quantum cryptography which use decoy settings to tightly estimate the statistics provided by perfect devices. As an illustration of its practicality, we use this technique to obtain a tight estimation of both the generalized Hong-Ou-Mandel dip in a beamsplitter with six input photons, as well as the three-photon coincidence probability at the output of a tritter. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1710.08495v1-abstract-full').style.display = 'none'; document.getElementById('1710.08495v1-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 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">8 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> New Journal of Physics 20, 043018 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1704.07178">arXiv:1704.07178</a> <span> [<a href="https://arxiv.org/pdf/1704.07178">pdf</a>, <a href="https://arxiv.org/ps/1704.07178">ps</a>, <a href="https://arxiv.org/format/1704.07178">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.94.022328">10.1103/PhysRevA.94.022328 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Measurement-Device-Independent Quantum Digital Signatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Puthoor%2C+I+V">Ittoop Vergheese Puthoor</a>, <a href="/search/quant-ph?searchtype=author&query=Amiri%2C+R">Ryan Amiri</a>, <a href="/search/quant-ph?searchtype=author&query=Wallden%2C+P">Petros Wallden</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Andersson%2C+E">Erika Andersson</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="1704.07178v1-abstract-short" style="display: inline;"> Digital signatures play an important role in software distribution, modern communication and financial transactions, where it is important to detect forgery and tampering. Signatures are a cryptographic technique for validating the authenticity and integrity of messages, software, or digital documents. The security of currently used classical schemes relies on computational assumptions. Quantum di… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.07178v1-abstract-full').style.display = 'inline'; document.getElementById('1704.07178v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1704.07178v1-abstract-full" style="display: none;"> Digital signatures play an important role in software distribution, modern communication and financial transactions, where it is important to detect forgery and tampering. Signatures are a cryptographic technique for validating the authenticity and integrity of messages, software, or digital documents. The security of currently used classical schemes relies on computational assumptions. Quantum digital signatures (QDS), on the other hand, provide information-theoretic security based on the laws of quantum physics. Recent work on QDS shows that such schemes do not require trusted quantum channels and are unconditionally secure against general coherent attacks. However, in practical QDS, just as in quantum key distribution (QKD), the detectors can be subjected to side-channel attacks, which can make the actual implementations insecure. Motivated by the idea of measurement-device-independent quantum key distribution (MDI-QKD), we present a measurement-device-independent QDS (MDI-QDS) scheme, which is secure against all detector side-channel attacks. Based on the rapid development of practical MDI-QKD, our MDI-QDS protocol could also be experimentally implemented, since it requires a similar experimental setup. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1704.07178v1-abstract-full').style.display = 'none'; document.getElementById('1704.07178v1-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 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">12 pages, 2 figures and supplementary material is included</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. A 94, 022328, 2016 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.01021">arXiv:1703.01021</a> <span> [<a href="https://arxiv.org/pdf/1703.01021">pdf</a>, <a href="https://arxiv.org/ps/1703.01021">ps</a>, <a href="https://arxiv.org/format/1703.01021">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.95.042338">10.1103/PhysRevA.95.042338 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental measurement-device-independent quantum digital signatures over a metropolitan network </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Yin%2C+H">Hua-Lei Yin</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+W">Wei-Long Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Tang%2C+Y">Yan-Lin Tang</a>, <a href="/search/quant-ph?searchtype=author&query=Zhao%2C+Q">Qi Zhao</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+H">Hui Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+X">Xiang-Xiang Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+W">Wei-Jun Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Li%2C+H">Hao Li</a>, <a href="/search/quant-ph?searchtype=author&query=Puthoor%2C+I+V">Ittoop Vergheese Puthoor</a>, <a href="/search/quant-ph?searchtype=author&query=You%2C+L">Li-Xing You</a>, <a href="/search/quant-ph?searchtype=author&query=Andersson%2C+E">Erika Andersson</a>, <a href="/search/quant-ph?searchtype=author&query=Wang%2C+Z">Zhen Wang</a>, <a href="/search/quant-ph?searchtype=author&query=Liu%2C+Y">Yang Liu</a>, <a href="/search/quant-ph?searchtype=author&query=Jiang%2C+X">Xiao Jiang</a>, <a href="/search/quant-ph?searchtype=author&query=Ma%2C+X">Xiongfeng Ma</a>, <a href="/search/quant-ph?searchtype=author&query=Zhang%2C+Q">Qiang Zhang</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Chen%2C+T">Teng-Yun Chen</a>, <a href="/search/quant-ph?searchtype=author&query=Pan%2C+J">Jian-Wei Pan</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="1703.01021v2-abstract-short" style="display: inline;"> Quantum digital signatures (QDS) provide a means for signing electronic communications with informationtheoretic security. However, all previous demonstrations of quantum digital signatures assume trusted measurement devices. This renders them vulnerable against detector side-channel attacks, just like quantum key distribution. Here, we exploit a measurement-device-independent (MDI) quantum networ… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.01021v2-abstract-full').style.display = 'inline'; document.getElementById('1703.01021v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.01021v2-abstract-full" style="display: none;"> Quantum digital signatures (QDS) provide a means for signing electronic communications with informationtheoretic security. However, all previous demonstrations of quantum digital signatures assume trusted measurement devices. This renders them vulnerable against detector side-channel attacks, just like quantum key distribution. Here, we exploit a measurement-device-independent (MDI) quantum network, over a 200-square-kilometer metropolitan area, to perform a field test of a three-party measurement-device-independent quantum digital signature (MDI-QDS) scheme that is secure against any detector side-channel attack. In so doing, we are able to successfully sign a binary message with a security level of about 1E-7. Remarkably, our work demonstrates the feasibility of MDI-QDS for practical applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.01021v2-abstract-full').style.display = 'none'; document.getElementById('1703.01021v2-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 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">5 pages, 1 figure, 2 tables, supplemental materials included as ancillary file</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, 042338 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.00493">arXiv:1703.00493</a> <span> [<a href="https://arxiv.org/pdf/1703.00493">pdf</a>, <a href="https://arxiv.org/format/1703.00493">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/s41467-017-01245-5">10.1038/s41467-017-01245-5 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Experimental measurement-device-independent quantum digital signatures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Roberts%2C+G+L">G. L. Roberts</a>, <a href="/search/quant-ph?searchtype=author&query=Lucamarini%2C+M">M. Lucamarini</a>, <a href="/search/quant-ph?searchtype=author&query=Yuan%2C+Z+L">Z. L. Yuan</a>, <a href="/search/quant-ph?searchtype=author&query=Dynes%2C+J+F">J. F. Dynes</a>, <a href="/search/quant-ph?searchtype=author&query=Comandar%2C+L+C">L. C. Comandar</a>, <a href="/search/quant-ph?searchtype=author&query=Sharpe%2C+A+W">A. W. Sharpe</a>, <a href="/search/quant-ph?searchtype=author&query=Shields%2C+A+J">A. J. Shields</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">M. Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Puthoor%2C+I+V">I. V. Puthoor</a>, <a href="/search/quant-ph?searchtype=author&query=Andersson%2C+E">E. Andersson</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="1703.00493v1-abstract-short" style="display: inline;"> We propose and experimentally implement a novel reconfigurable quantum key distribution (QKD) scheme, where the users can switch in real time between conventional QKD and the recently-introduced measurement-device-independent (MDI) QKD. Through this setup, we demonstrate the distribution of quantum keys between three remote parties connected by only two quantum channels, a previously unattempted t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.00493v1-abstract-full').style.display = 'inline'; document.getElementById('1703.00493v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.00493v1-abstract-full" style="display: none;"> We propose and experimentally implement a novel reconfigurable quantum key distribution (QKD) scheme, where the users can switch in real time between conventional QKD and the recently-introduced measurement-device-independent (MDI) QKD. Through this setup, we demonstrate the distribution of quantum keys between three remote parties connected by only two quantum channels, a previously unattempted task. Moreover, as a prominent application, we extract the first quantum digital signature (QDS) rates from a network that uses a measurement-device-independent link. In so doing, we introduce an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and increasing the final QDS rate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.00493v1-abstract-full').style.display = 'none'; document.getElementById('1703.00493v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">7 pages, 4 figures, supplementary materials included as ancillary file</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 8, 1098 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.06499">arXiv:1610.06499</a> <span> [<a href="https://arxiv.org/pdf/1610.06499">pdf</a>, <a href="https://arxiv.org/ps/1610.06499">ps</a>, <a href="https://arxiv.org/format/1610.06499">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/10.1088/2058-9565/aa89bd">10.1088/2058-9565/aa89bd <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Security of quantum key distribution with iterative sifting </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</a>, <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Kato%2C+G">Go Kato</a>, <a href="/search/quant-ph?searchtype=author&query=Lim%2C+C+C+W">Charles Ci Wen Lim</a>, <a href="/search/quant-ph?searchtype=author&query=Azuma%2C+K">Koji Azuma</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="1610.06499v2-abstract-short" style="display: inline;"> Several quantum key distribution (QKD) protocols employ iterative sifting. After each quantum transmission round, Alice and Bob disclose part of their setting information (including their basis choices) for the detected signals. The quantum phase of the protocol then ends when the numbers of detected signals per basis exceed certain pre-agreed threshold values. Recently, however, Pfister et al. [N… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.06499v2-abstract-full').style.display = 'inline'; document.getElementById('1610.06499v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.06499v2-abstract-full" style="display: none;"> Several quantum key distribution (QKD) protocols employ iterative sifting. After each quantum transmission round, Alice and Bob disclose part of their setting information (including their basis choices) for the detected signals. The quantum phase of the protocol then ends when the numbers of detected signals per basis exceed certain pre-agreed threshold values. Recently, however, Pfister et al. [New J. Phys. 18 053001 (2016)] showed that iterative sifting makes QKD insecure, especially in the finite key regime, if the parameter estimation for privacy amplification uses the random sampling theory. This implies that a number of existing finite key security proofs could be flawed and cannot guarantee security. Here, we solve this serious problem by showing that the use of Azuma's inequality for parameter estimation makes QKD with iterative sifting secure again. This means that the existing protocols whose security proof employs this inequality remain secure even if they employ iterative sifting. Also, our results highlight a fundamental difference between the random sampling theorem and Azuma's inequality in proving security. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.06499v2-abstract-full').style.display = 'none'; document.getElementById('1610.06499v2-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 May, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 20 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">9 pages. We have found a flaw in the first version, which we have corrected in the revised version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Quantum Science and Technology, vol. 3, no. 1, 014002 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1607.05814">arXiv:1607.05814</a> <span> [<a href="https://arxiv.org/pdf/1607.05814">pdf</a>, <a href="https://arxiv.org/format/1607.05814">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/PhysRevLett.117.250505">10.1103/PhysRevLett.117.250505 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Insecurity of detector-device-independent quantum key distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Sajeed%2C+S">Shihan Sajeed</a>, <a href="/search/quant-ph?searchtype=author&query=Huang%2C+A">Anqi Huang</a>, <a href="/search/quant-ph?searchtype=author&query=Sun%2C+S">Shihai Sun</a>, <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Makarov%2C+V">Vadim Makarov</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</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="1607.05814v1-abstract-short" style="display: inline;"> Detector-device-independent quantum key distribution (ddiQKD) held the promise of being robust to detector side-channels, a major security loophole in QKD implementations. In contrast to what has been claimed, however, we demonstrate that the security of ddiQKD is not based on post-selected entanglement, and we introduce various eavesdropping strategies that show that ddiQKD is in fact insecure ag… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05814v1-abstract-full').style.display = 'inline'; document.getElementById('1607.05814v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.05814v1-abstract-full" style="display: none;"> Detector-device-independent quantum key distribution (ddiQKD) held the promise of being robust to detector side-channels, a major security loophole in QKD implementations. In contrast to what has been claimed, however, we demonstrate that the security of ddiQKD is not based on post-selected entanglement, and we introduce various eavesdropping strategies that show that ddiQKD is in fact insecure against detector side-channel attacks as well as against other attacks that exploit device's imperfections of the receiver. Our attacks are valid even when the QKD apparatuses are built by the legitimate users of the system themselves, and thus free of malicious modifications, which is a key assumption in ddiQKD. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.05814v1-abstract-full').style.display = 'none'; document.getElementById('1607.05814v1-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 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">7 pages, 5 figures, 1 table</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 117, 250505 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1506.04819">arXiv:1506.04819</a> <span> [<a href="https://arxiv.org/pdf/1506.04819">pdf</a>, <a href="https://arxiv.org/format/1506.04819">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/nphoton.2015.206">10.1038/nphoton.2015.206 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Discrete-variable measurement-device-independent quantum key distribution suitable for metropolitan networks </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Xu%2C+F">Feihu Xu</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Qi%2C+B">Bing Qi</a>, <a href="/search/quant-ph?searchtype=author&query=Qian%2C+L">Li Qian</a>, <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</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="1506.04819v2-abstract-short" style="display: inline;"> We demonstrate that, with a fair comparison, the secret key rate of discrete-variable measurement-device-independent quantum key distribution (DV-MDI-QKD) with high-efficiency single-photon detectors and good system alignment is typically rather high and thus highly suitable for not only long distance communication but also metropolitan networks. The previous reservation on the key rate and suitab… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1506.04819v2-abstract-full').style.display = 'inline'; document.getElementById('1506.04819v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1506.04819v2-abstract-full" style="display: none;"> We demonstrate that, with a fair comparison, the secret key rate of discrete-variable measurement-device-independent quantum key distribution (DV-MDI-QKD) with high-efficiency single-photon detectors and good system alignment is typically rather high and thus highly suitable for not only long distance communication but also metropolitan networks. The previous reservation on the key rate and suitability of DV-MDI-QKD for metropolitan networks expressed by Pirandola et al. [Nature Photon. 9, 397 (2015)] was based on an unfair comparison with low-efficiency detectors and high quantum bit error rate, and is, in our opinion, unjustified. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1506.04819v2-abstract-full').style.display = 'none'; document.getElementById('1506.04819v2-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 June, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 15 June, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">8 pages, 2 figures; one appendix added to reply to arXiv:1506.06748</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Photonics, 9, 772 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1505.05303">arXiv:1505.05303</a> <span> [<a href="https://arxiv.org/pdf/1505.05303">pdf</a>, <a href="https://arxiv.org/format/1505.05303">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/nphoton.2014.149">10.1038/nphoton.2014.149 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Secure Quantum Key Distribution </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Lo%2C+H">Hoi-Kwong Lo</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</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="1505.05303v1-abstract-short" style="display: inline;"> Secure communication plays a crucial role in the Internet Age. Quantum mechanics may revolutionise cryptography as we know it today. In this Review Article, we introduce the motivation and the current state of the art of research in quantum cryptography. In particular, we discuss the present security model together with its assumptions, strengths and weaknesses. After a brief introduction to recen… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.05303v1-abstract-full').style.display = 'inline'; document.getElementById('1505.05303v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1505.05303v1-abstract-full" style="display: none;"> Secure communication plays a crucial role in the Internet Age. Quantum mechanics may revolutionise cryptography as we know it today. In this Review Article, we introduce the motivation and the current state of the art of research in quantum cryptography. In particular, we discuss the present security model together with its assumptions, strengths and weaknesses. After a brief introduction to recent experimental progress and challenges, we survey the latest developments in quantum hacking and counter-measures against it. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1505.05303v1-abstract-full').style.display = 'none'; document.getElementById('1505.05303v1-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 May, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 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">13 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Photonics 8, 595-604 (2014) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1504.08151">arXiv:1504.08151</a> <span> [<a href="https://arxiv.org/pdf/1504.08151">pdf</a>, <a href="https://arxiv.org/ps/1504.08151">ps</a>, <a href="https://arxiv.org/format/1504.08151">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/10.1088/1367-2630/17/9/093011">10.1088/1367-2630/17/9/093011 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Finite-key security analysis of quantum key distribution with imperfect light sources </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/quant-ph?searchtype=author&query=Mizutani%2C+A">Akihiro Mizutani</a>, <a href="/search/quant-ph?searchtype=author&query=Curty%2C+M">Marcos Curty</a>, <a href="/search/quant-ph?searchtype=author&query=Lim%2C+C+C+W">Charles Ci Wen Lim</a>, <a href="/search/quant-ph?searchtype=author&query=Imoto%2C+N">Nobuyuki Imoto</a>, <a href="/search/quant-ph?searchtype=author&query=Tamaki%2C+K">Kiyoshi Tamaki</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="1504.08151v1-abstract-short" style="display: inline;"> In recent years, the gap between theory and practice in quantum key distribution (QKD) has been significantly narrowed, particularly for QKD systems with arbitrarily awed optical receivers. The status for QKD systems with imperfect light sources is however less satisfactory, in the sense that the resulting secure key rates are often overly-dependent on the quality of state preparation. This is esp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.08151v1-abstract-full').style.display = 'inline'; document.getElementById('1504.08151v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1504.08151v1-abstract-full" style="display: none;"> In recent years, the gap between theory and practice in quantum key distribution (QKD) has been significantly narrowed, particularly for QKD systems with arbitrarily awed optical receivers. The status for QKD systems with imperfect light sources is however less satisfactory, in the sense that the resulting secure key rates are often overly-dependent on the quality of state preparation. This is especially the case when the channel loss is high. Very recently, to overcome this limitation, Tamaki et al proposed a QKD protocol based on the so-called rejected data analysis, and showed that its security|in the limit of infinitely long keys|is almost independent of any encoding flaw in the qubit space, being this protocol compatible with the decoy state method. Here, as a step towards practical QKD, we show that a similar conclusion is reached in the finite-key regime, even when the intensity of the light source is unstable. More concretely, we derive security bounds for a wide class of realistic light sources and show that the bounds are also efficient in the presence of high channel loss. Our results strongly suggest the feasibility of long distance provably-secure communication with imperfect light sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1504.08151v1-abstract-full').style.display = 'none'; document.getElementById('1504.08151v1-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 April, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">27 pages, 7 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. 17, 093011 (2015) </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Curty%2C+M&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Curty%2C+M&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Curty%2C+M&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <div class="is-hidden-tablet">  <span class="help" style="display: inline-block;"><a href="https://github.com/arXiv/arxiv-search/releases">Search v0.5.6 released 2020-02-24</a>  </span> </div> </div> </main> <footer> <div class="columns is-desktop" role="navigation" aria-label="Secondary">  <div class="column"> <div class="columns"> <div class="column"> <ul 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