Quantum sensing employs quantum resources of a sensor to attain a smaller estimation error of physical quantities than the limit constrained by classical physics. To measure a quantum reservoir, which is significant in decoherence control, a nonunitary-encoding sensing scheme becomes necessary. However, previous studies showed that the reservoir-induced degradation to quantum resources of the sensor makes the errors divergent with the increase of encoding time. We here propose a scheme to use $N$ two-level systems as the sensor to measure a quantum reservoir. A threshold, above which the shot-noise-limited sensing error saturates or even persistently decreases with the encoding time, is uncovered. Our analysis reveals that it is due to the formation of a bound state of the total sensor-reservoir system. Solving the outstanding error-divergency problem in previous studies, our result supplies an insightful guideline in realizing a sensitive measurement of quantum reservoirs.
Quantum sensing explores protocols using the quantum resource of sensors to achieve highly sensitive measurement of physical quantities. The conventional schemes generally use unitary dynamics to encode quantities into sensor states. In order to measure the spectral density of a quantum reservoir, which plays a vital role in controlling the reservoir-caused decoherence to microscopic systems, we propose a nonunitary-encoding optical sensing scheme. Although the nonunitary dynamics for encoding in turn degrades the quantum resource, we surprisingly find a mechanism to make the encoding time a r…
Reservoir computing is a temporal information processing system that exploits artificial or physical dissipative dynamics to learn a dynamical system and generate the target time-series. This paper proposes the use of real superconducting quantum computing devices as the reservoir, where the dissipative property is served by the natural noise added to the quantum bits. The performance of this natural quantum reservoir is demonstrated in a benchmark time-series regression problem and a practical problem classifying different objects based on temporal sensor data. In both cases the proposed rese…
We investigate the sensing performance of a single-qubit quantum thermometer within a non-Markovian dynamical framework. By employing an exactly numerical hierarchical equations of the motion method, we go beyond traditional paradigms of the Born-Markov theory, the pure dephasing mechanism, and the weak-coupling approximation, which were commonly used in many previous studies of quantum thermometry. We find (i) the non-Markovian characteristics may boost the estimation efficiency, (ii) the sensitivity of quantum thermometry can be effectively optimized by engineering the proportions of differe…
Thresholded Quantum Sensing with a Frustrated Kitaev Trimer
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Quantum Science Center, Oak Ridge（橡树岭量子科学中心）；Theoretical Division, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室理论部）；ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（ICFO-光子科学研究所，巴塞罗那科学技术研究院）；MPA-Q, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室MPA-Q）
Long-time fermionic quantum transport with controlled full-state error using an adaptive reservoir-mode window
Russian Quantum Center（俄罗斯量子中心）；Moscow Institute of Physics and Technology（莫斯科物理技术学院）；Faculty of Physics, M.V.Lomonosov Moscow State University（莫斯科国立大学物理系）；National Research Nuclear University MEPhI（莫斯科工程物理学院）
Quantum Light Detection with Enhanced Photonic Neural Network
University of Warsaw（华沙大学）；Polish Academy of Sciences（波兰科学院）；Nanyang Technological University（南洋理工大学）；CNRS（法国国家科学研究中心）；Université Côte d’Azur（蔚蓝海岸大学）；Sorbonne Université（索邦大学）；National University of Singapore（新加坡国立大学）
Improving the loss threshold for quantum advantage in photonic sensors by complete photon counting
University of Oxford（牛津大学）；Imperial College London（伦敦帝国学院）；National Research Council of Canada（加拿大国家研究委员会）；National Institute of Standards and Technology（美国国家标准与技术研究院）；ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology（ICFO-光子科学研究所，巴塞罗那科学技术研究院）；Universitat Politecnica de Catalunya（加泰罗尼亚理工大学）
Recent progresses have revealed that quantum systems with multiple position-dependent couplings, e.g., giant atoms, can exhibit some unconventional phenomena, such as non-exponential decay etc. However, their potential applications are still open questions. In this paper, we propose a giant-cavity-based quantum sensor for the first time, whose performance can be greatly enhanced compared to traditional cavity-based sensors. In our proposal, two cavities couple to a dissipative reservoir at multiple points while they couple to a gain reservoir in a single-point way. To detecting a unknown param…
In recent years, many peculiar sensors have been proposed, such as the sensors based on exceptional points, Parity-Time symmetric structures or non-reciprocal systems. It is crucial to evaluate the fundamental limit of these sensing schemes and to judge whether there is an enhanced performance. Several papers have already investigated the fundamental limits based on different aspects and criteria, some led to different conclusions. In this paper, we suggest that for linear bosonic sensors that can be modeled as coupled oscillators below threshold, a measurement of the mode frequency $w_0$ can …
A Reservoir Computing Approach to Quantum Gate Synthesis
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Scuola Normale Superiore（比萨高等师范学院）；IFISC (UIB-CSIC)（巴利阿里群岛大学-西班牙最高科学研究委员会综合系统物理学与复杂系统研究所）；USRA Research Institute for Advanced Computer Science (RIACS)（美国研究协会高级计算机科学研究所）
Low Threshold Acquisition controller for Skipper CCDs
Skipper电荷耦合器件（Skipper-CCD）的发展是用于感测非常弱的电离粒子的重大技术突破。该传感器允许通过明确确定由每个单元或像素收集的电荷信号来达到硅材料作为电荷信号传感器的最终灵敏度，即使对于单个电子-空穴对电离也是如此。该技术的广泛使用受到限制，因为缺乏特定设备来操作传感器的最终性能。在这项工作中，一个简单的，单板跳跃CCD控制器，目的是在高灵敏度的科学应用中的探测器的操作。本文介绍了低阈值采集（LTA）的主要组成部分和功能，以及连接到Skipper-CCD传感器时的实验结果。测量结果表明，前所未有的深亚电子噪声为0.039 e $^-_{rms}$ /pix的5000像素的测量。
Background cancellation for frequency-selective quantum sensing
Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）；Ecole Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；University of Maryland, College Park（马里兰大学帕克分校）；Fermi National Accelerator Laboratory（费米国家加速器实验室）
The Role of Entanglement in Quantum Reservoir Computing with Coupled Kerr Nonlinear Oscillators
Department of Physics and Astronomy, University of Calgary（卡尔加里大学物理与天文学系）；Institute for Quantum Science and Technology, University of Calgary（卡尔加里大学量子科学与技术研究所）；Hotchkiss Brain Institute, University of Calgary（卡尔加里大学霍奇基斯脑研究所）；Department of Physics, University of New Brunswick（新不伦瑞克大学物理系）
Signal-to-noise ratio (SNR) detection statistic has wide-spread applications. A potential event is recorded when the SNR from a specific template exceeds a threshold set by a desired false positive rate. In template bank searches, the generalization of the SNR statistic is the SNR-max statistic, defined as the maximum of the absolute value of SNRs from individual template matching. While individual SNR realizations are Gaussian distributed, SNR-max probability distribution is non-Gaussian. Moreover, as the individual template-bank SNRs are computed using the same network data streams, SNRs bec…
Quantum Parity Detectors: a qubit based particle detection scheme with meV thresholds for rare-event searches
Washington University in St. Louis（华盛顿大学）；California Institute of Technology（加州理工学院）；Weizmann Institute of Science（魏茨曼科学研究所）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
