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Entanglement plays a crucial role in proposals for quantum metrology, yet demonstrating quantum enhancement in sensing with sustained spin entanglement remains a challenging endeavor. Here, we combine optical pumping and continuous quantum…

Quantum Physics · Physics 2025-04-09 Junlei Duan , Zhiwei Hu , Xingda Lu , Liantuan Xiao , Suotang Jia , Klaus Mølmer , Yanhong Xiao

Quantum entanglement can provide enhanced precision beyond standard quantum limit (SQL), the highest precision achievable with classical means. It remains challenging, however, to observe large enhancement limited by the experimental…

Quantum Gases · Physics 2022-12-20 Tian-Wei Mao , Qi Liu , Xin-Wei Li , Jia-Hao Cao , Feng Chen , Wen-Xin Xu , Meng Khoon Tey , Yi-Xiao Huang , Li You

In the rapidly evolving field of quantum computing, optimizing quantum circuits for specific tasks is crucial for enhancing performance and efficiency. More recently, quantum sensing has become a distinct and rapidly growing branch of…

Quantum Physics · Physics 2025-09-01 Laxmisha Ashok Attisara , Sathish Kumar

Quantum metrology makes use of coherent superpositions to detect weak signals. While in principle the sensitivity can be improved by increasing the density of sensing particles, in practice this improvement is severely hindered by…

We study experimentally the fundamental limits of sensitivity of an atomic radio-frequency magnetometer. First we apply an optimal sequence of state preparation, evolution, and the back-action evading measurement to achieve a nearly…

Quantum Physics · Physics 2011-01-28 W. Wasilewski , K. Jensen , H. Krauter , J. J. Renema , M. V. Balabas , E. S. Polzik

Quantum entanglement has been generated and verified in cold-atom experiments and used to make atom-interferometric measurements below the shot-noise limit. However, current state-of-the-art cold-atom devices exploit separable (i.e.…

Quantum Physics · Physics 2021-04-13 Stuart S. Szigeti , Onur Hosten , Simon A. Haine

Spin squeezing generated via inter-atom entanglement in multilevel atomic ensembles provides a powerful resource for quantum-enhanced metrology. Existing schemes that harness internal atomic degrees of freedom to boost squeezing typically…

Quantum Physics · Physics 2026-05-18 Zhiwei Hu , Youwei Zhang , Junlei Duan , Mingfeng Wang , Yanhong Xiao

The main advantage of quantum metrology relies on the effective use of entanglement, which indeed allows us to achieve strictly better estimation performance over the standard quantum limit. In this paper, we propose an analogous method…

Quantum Physics · Physics 2017-06-13 Naoki Yamamoto , Tomoaki Mikami

Quantum metrology experiments in atomic physics and quantum optics have demonstrated measurement accuracy beyond the shot-noise limit via multi-particle entanglement. At the same time, electron microscopy, an essential tool for…

Entanglement is a fundamental feature of quantum mechanics and holds great promise for enhancing metrology and communications. Much of the focus of quantum metrology so far has been on generating highly entangled quantum states that offer…

We study multi-parameter sensing of 2D and 3D vector fields within the Bayesian framework for $SU(2)$ quantum interferometry. We establish a method to determine the optimal quantum sensor, which establishes the fundamental limit on the…

Quantum Physics · Physics 2023-06-05 Raphael Kaubruegger , Athreya Shankar , Denis V. Vasilyev , Peter Zoller

The shot-noise detection limit in current high-precision atomic magnetometry is a manifestation of quantum fluctuations that scale as the square root of N in an ensemble of N particles. However, there is a general expectation that the…

Quantum Physics · Physics 2007-05-23 JM Geremia , John K. Stockton , Andrew C. Doherty , Hideo Mabuchi

Atom interferometers are reaching sensitivities fundamentally constrained by quantum fluctuations. A main challenge is to integrate entanglement into quantum sensing protocols to enhance precision while ensuring robustness against noise and…

Entangled many-body states enable high-precision quantum sensing beyond the standard quantum limit. We develop interferometric sensing protocols based on quantum critical wavefunctions and compare their performance with…

Quantum Physics · Physics 2026-01-09 Yinan Chen , Sara Murciano , Pablo Sala , Jason Alicea

Spins are prototypical systems with the potential to probe magnetic fields down to the atomic scale limit. Exploiting their quantum nature through appropriate sensing protocols allows to enlarge their applicability to fields not always…

Quantum Physics · Physics 2024-04-26 Claudio Bonizzoni , Alberto Ghirri , Fabio Santanni , Marco Affronte

Quantum technologies use entanglement to outperform classical technologies, and often employ strong cooling and isolation to protect entangled entities from decoherence by random interactions. Here we show that the opposite strategy -…

Quantum systems are powerful detectors with wide-ranging applications from scanning probe microscopy of materials to biomedical imaging. Nitrogen vacancy (NV) centers in diamond, for instance, can be operated as qubits for sensing of…

Quantum Physics · Physics 2024-06-07 Christopher I. Timms , Michael H. Kolodrubetz

Interactions among sensors can provide, in addition to entanglement, an important resource for boosting the precision in quantum estimation protocols. Dephasing noise, however, remains a leading source of decoherence in state-of-the-art…

Quantum Physics · Physics 2025-01-03 Francisco Riberi , Lorenza Viola

Quantum sensing takes advantage of well controlled quantum systems for performing measurements with high sensitivity and precision. We have implemented a concept for quantum sensing with arbitrary frequency resolution, independent of the…

Quantum Physics · Physics 2017-06-07 J. M. Boss , K. S. Cujia , J. Zopes , C. L. Degen

Building scalable quantum systems that demonstrate genuine performance enhancement based on entanglement is a major scientific goal for fields including computing, networking, simulations, and metrology. The tremendous challenge arises from…