Local detection of magnetic fields is crucial for characterizing nano- and micro-materials and has been implemented using various scanning techniques or even diamond quantum sensors. Diamond nanoparticles (nanodiamonds) offer an attractive opportunity to chieve high spatial resolution because they can easily be close to the target within a few 10 nm simply by attaching them to its surface. A physical model for such a randomly oriented nanodiamond ensemble (NDE) is available, but the complexity of actual experimental conditions still limits the accuracy of deducing magnetic fields. Here, we demonstrate magnetic field imaging with high accuracy of 1.8 $μ$T combining NDE and machine learning without any physical models. We also discover the field direction dependence of the NDE signal, suggesting the potential application for vector magnetometry and improvement of the existing model. Our method further enriches the performance of NDE to achieve the accuracy to visualize mesoscopic current and magnetism in atomic-layer materials and to expand the applicability in arbitrarily shaped materials, including living organisms. This achievement will bridge machine learning and quantum sensing for accurate measurements.
Conventional criticality-based quantum metrological schemes work only at zero or very low temperature because the quantum uncertainty around the quantum phase-transition point is generally erased by thermal fluctuations with the increase of temperature. Such an ultralow-temperature requirement severely restricts the development of quantum critical metrology. In this paper, we propose a thermodynamic-criticality-enhanced quantum sensing scenario at finite temperature. In our scheme, a qubit is employed as a quantum sensor to estimate parameters of interest in the Dicke model which experiences a…
Atomic-scale imaging offers a reliable tool to directly measure the movement of microscopic particles. We present a scheme for achieving a nondestructive and ultrasensitive imaging of Rydberg atoms within an ensemble of cold probe atoms. This is made possible by the interaction-enhanced electromagnetically induced transparency at off-resonance which enables an extremely narrow absorption dip for an enhanced transmission. Through the transmission of a probe beam, we obtain the distribution of Rydberg atoms with both high spatial resolution and fast response, which ensures a more precise real-ti…
Variational quantum circuits (VQCs) built upon noisy intermediate-scale quantum (NISQ) hardware, in conjunction with classical processing, constitute a promising architecture for quantum simulations, classical optimization, and machine learning. However, the required VQC depth to demonstrate a quantum advantage over classical schemes is beyond the reach of available NISQ devices. Supervised learning assisted by an entangled sensor network (SLAEN) is a distinct paradigm that harnesses VQCs trained by classical machine-learning algorithms to tailor multipartite entanglement shared by sensors for…
Optimizing quantum-enhanced Bayesian multiparameter estimation of phase and noise in practical sensors
Scuola Normale Superiore（高等师范学校）；Istituto Nanoscienze-CNR（意大利国家研究委员会纳米科学研究所）；Sapienza Università di Roma（罗马第一大学）；Universitá di Napoli “Federico II”（那不勒斯费德里科二世大学）；INFN, Sez. di Napoli（意大利国家核物理研究院那不勒斯分部）
Recently, there have been significant developments to detect nuclear spins with an nitrogen vacancy (NV) center in diamond. However, due to the nature of the short range dipole-dipole interaction, it takes a long time to detect distant nuclear spins with the NV centers. Here, we propose a rapid detection of nuclear spins with an entanglement between the NV centers. We show that the necessary time to detect the nuclear spins with the entanglement is several orders of magnitude shorter than that with separable NV centers. Our result pave the way for new applications in nanoscale nuclear magnetic…
量子资源可以提高设备的灵敏度，使其超过经典散粒噪声极限，因此，通过开发量子增强传感器，彻底改变了计量领域。特别地，广泛用于生物和化学传感应用的等离子体传感器提供了将这种增强带到现实生活设备的独特机会。在这里，我们使用明亮的纠缠双光束来提高用于测量局部折射率变化的等离子体传感器的灵敏度。我们证明了最先进的等离子体传感器的灵敏度的56%的量子增强，测量的灵敏度在$10^{-10}$ RIU $/\sqrt{\textrm{Hz}}$的数量级上，比量子增强等离子体传感器的先前的原理验证实施方式好近5个数量级。这些结果有望显着增强超痕量标记自由等离子体传感，并将找到他们的方式进入从生物医学应用到化学检测等领域。
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…
Nitrogen-vacancy (NV) centers in diamond can be used as quantum sensors to image the magnetic field with nanoscale resolution. However, nanoscale electric-field mapping has not been achieved so far because of the relatively weak coupling strength between NV and electric field. Using individual shallow NVs, here we succeeded to quantitatively image the contours of electric field from a sharp tip of a qPlus-based atomic force microscope (AFM), and achieved a spatial resolution of ~10 nm. Through such local electric fields, we demonstrated electric control of NV's charge state with sub-5 nm preci…
Nitrogen-vacancy (NV) center in diamond is a promising quantum sensor with remarkably versatile sensing capabilities. While scanning NV magnetometry is well-established, NV electrometry has been so far limited to bulk diamonds. Here we demonstrate imaging external alternating (AC) and direct (DC) electric fields with a single NV at the apex of a diamond scanning tip under ambient conditions. A strong electric field screening effect is observed at low frequencies due to charge noise on the surface. We quantitatively measure its frequency dependence, and overcome this screening by mechanically o…
Correlated photon pairs, carrying strong quantum correlations, have been harnessed to bring quantum advantages to various fields from biological imaging to range finding. Such inherent non-classical properties support extracting more valid signals to build photon-limited images even in low flux-level, where the shot noise becomes dominant as light source decreases to single-photon level. Optimization by numerical reconstruction algorithms is possible but require thousands of photon-sparse frames, thus unavailable in real time. Here, we present an experimental fast correlated-photon imaging enh…
Superresolution imaging with entanglement-enhanced telescopy
College of Optical Sciences, University of Arizona（亚利桑那大学光学科学学院）；Department of Electrical and Computer Engineering, University of Maryland, College Park（马里兰大学电气与计算机工程系）；NASA Goddard Space Flight Center（美国国家航空航天局戈达德太空飞行中心）
