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How can we analyze quantum correlations in large and noisy systems without quantum state tomography? An established method is to measure total angular momenta and employ the so-called spin-squeezing inequalities based on their expectations…

Quantum Physics · Physics 2024-08-23 Jan Lennart Bönsel , Satoya Imai , Ye-Chao Liu , Otfried Gühne

In recent years, distributed quantum sensing has gained interest for a range of applications requiring networks of sensors, from global-scale clock synchronization to high energy physics. In particular, a network of entangled sensors can…

We investigate the phase sensitivity of a Mach-Zehnder interferometer using a special class of generalized coherent states constructed from generalized Heisenberg and deformed $su(1,1)$ algebras. These states, derived from a perturbed…

Quantum Physics · Physics 2025-11-03 N. E. Abouelkhir , A. Slaoui , R. Ahl Laamara

Information recycling has been shown to improve the sensitivity of atom interferometers by exploiting atom-light entanglement. In this paper, we apply information recycling to an interferometer where the input quantum state has been…

Quantum Physics · Physics 2015-05-04 Simon A. Haine , Stuart S. Szigeti , Matthias D. Lang , Carlton M. Caves

We obtain a lower bound on the sum of two orthogonal spin component variances in a plane. This gives a novel planar uncertainty relation which holds even when the Heisenberg relation is not useful. We investigate the asymptotic, large $J$…

Quantum Physics · Physics 2014-05-09 Q. Y. He , Shi-Guo Peng , P. D. Drummond , M. D. Reid

We analyze a scheme that uses quantum nondemolition measurements to induce squeezing of a spinor Bose-Einstein condensate in a double well trap. In a previous paper [Ilo-Okeke et al. Phys. Rev. A \textbf{104}, 053324 (2021)], we introduced…

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…

Improving the precision of measurements is a significant scientific challenge. The challenge is twofold: first, overcoming noise that limits the precision given a fixed amount of a resource, N, and second, improving the scaling of precision…

High precision interferometers are the building blocks of precision metrology and the ultimate interferometric sensitivity is limited by the quantum noise. Here we propose and experimentally demonstrate a compact quantum interferometer…

Quantum Physics · Physics 2020-05-20 Xiaojie Zuo , Zhihui Yan , Yanni Feng , Jingxu Ma , Xiaojun Jia , Changde Xie , Kunchi Peng

We propose a measurement setup reaching Heisenberg scaling precision for the estimation of any distributed parameter $\varphi$ (not necessarily a phase) encoded into a generic $M$-port linear network composed only of passive elements. The…

Quantum Physics · Physics 2021-12-23 Giovanni Gramegna , Danilo Triggiani , Paolo Facchi , Frank A. Narducci , Vincenzo Tamma

The Heisenberg limit is the superior precision available by entanglement sensors. However, entanglementis fragile against dephasing, and there is no known quantum metrology protocol that can achieve Heisenberg limited sensitivity with the…

Quantum Physics · Physics 2018-09-05 Yuichiro Matsuzaki , Shiro Saito , William J. Munro

Quantum entanglement is recognized as a fundamental resource in quantum information processing and is essential for understanding quantum many-body physics. However, experimentally detecting entanglement, particularly in many-particle…

Quantum Physics · Physics 2025-08-13 Hao-Yue Qi , Wei Zheng

Quantum entanglement is a powerful quantum resource for enhancing measurement precision beyond classical limit. % Here we propose an entanglement-enhanced symmetry-protected destructive many-body Ramsey interferometry for precise parameter…

Quantum Physics · Physics 2025-09-11 Sijie Chen , Jiahao Huang , Min Zhuang , Chaohong Lee

Studies of quantum metrology have shown that the use of many-body entangled states can lead to an enhancement in sensitivity when compared to product states. In this paper, we quantify the metrological advantage of entanglement in a setting…

There has been much interest in developing phase estimation schemes which beat the so-called Heisenberg limit, i.e., for which the phase resolution scales better than 1/n, where n is a measure of resources such as the average photon number…

Quantum Physics · Physics 2013-07-11 Michael J. W. Hall

We investigate phase transitions in the nonequilibrium dynamics of power-law interacting spin-1/2 bilayer XXZ models, which have recently been shown to allow generation of entanglement in the form of two-mode squeezing. We find a transition…

Quantum Physics · Physics 2025-12-11 Arman Duha , S. E. Begg , Thomas Bilitewski

We observe collective quantum spin states of an ensemble of atoms in a one-dimensional light-atom interface. Strings of hundreds of cesium atoms trapped in the evanescent fiel of a tapered nanofiber are prepared in a coherent spin state, a…

Quantum Physics · Physics 2018-07-18 J. -B. Béguin , J. H. Müller , J. Appel , E. S. Polzik

We analyze the Heisenberg limit on phase estimation for Gaussian states. In the analysis, no reference to a phase operator is made. We prove that the squeezed vacuum state is the most sensitive for a given average photon number. We provide…

Quantum Physics · Physics 2007-05-23 Alex Monras

We propose a quantum feedback scheme for producing deterministically reproducible spin squeezing. The results of a continuous nondemolition atom number measurement are fed back to control the quantum state of the sample. For large samples…

Quantum Physics · Physics 2009-11-07 L. K. Thomsen , S. Mancini , H. M. Wiseman

We show that the phase sensitivity $\Delta \theta$ of a Mach-Zehnder interferometer fed by a coherent state in one input port and squeezed-vacuum in the other one is i) independent from the true value of the phase shift and ii) can reach…

Quantum Physics · Physics 2009-11-13 L. Pezze' , A. Smerzi