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A central feature of quantum metrology is the possibility of Heisenberg scaling, a quadratic improvement over the limits of classical statistics. This scaling, however, is notoriously fragile to noise. While for some noise types it can be…

Quantum Physics · Physics 2022-06-08 Giulio Chiribella , Xiaobin Zhao

We introduce a systematic protocol for constructing quantum Hilbert-space-fragmented Hamiltonians, whose Krylov-sector structure, unlike in classically fragmented models, can be fully resolved only in an entangled basis. The protocol takes…

Quantum Physics · Physics 2026-04-27 Yiqiu Han , Oliver Hart , Alexey Khudorozhkov , Rahul Nandkishore

A quantum model exhibits Hilbert space fragmentation (HSF) if its Hilbert space decomposes into exponentially many dynamically disconnected subspaces, known as Krylov subspaces. A model may however have different HSFs depending on the…

Statistical Mechanics · Physics 2026-01-05 Bo-Ting Chen , Yu-Ping Wang , Biao Lian

Quantum entanglement has been identified as a crucial concept underlying many intriguing phenomena in condensed matter systems, such as topological phases or many-body localization. Recently, instead of considering mere quantifiers of…

Quantum Physics · Physics 2024-02-12 Niklas Euler , Martin Gärttner

Quantum entanglement, in the form of spin squeezing, is known to improve the sensitivity of atomic sensors to static or slowly varying fields. Sensing transient events presents a distinct challenge, requires different analysis tools, and…

Quantum Physics · Physics 2025-12-08 Julia Amoros-Binefa

An attractive approach for stabilizing entangled many-body spin states is to employ engineered dissipation. Most existing proposals either target relatively simple collective spin states, or require numerous independent and complex…

Quantum Physics · Physics 2026-03-13 Anjun Chu , Mikhail Mamaev , Martin Koppenhöfer , Ming Yuan , Aashish A. Clerk

Quantum metrology fundamentally relies upon the efficient management of quantum uncertainties. We show that, under equilibrium conditions, the management of quantum noise becomes extremely flexible around the quantum critical point of a…

Quantum Physics · Physics 2018-07-18 Irénée Frérot , Tommaso Roscilde

Developing the isolation and control of ultracold atomic systems to the level of single quanta has led to significant advances in quantum sensing, yet demonstrating a quantum advantage in real world applications by harnessing entanglement…

Spin squeezing plays a crucial role in quantum metrology and quantum information science. Its generation is the prerequisite for further applications but still faces an enormous challenge since the existing physical systems rarely contain…

Quantum Physics · Physics 2023-11-09 Long-Gang Huang , Xuanchen Zhang , Yanzhen Wang , Zhenxing Hua , Yuanjiang Tang , Yong-Chun Liu

In the scenario of the probe-ancilla interaction, we propose a quantum metrology protocol by the unconditional measurement on the ancillary qubit after an optimized period of joint evolution from product state. Its key element is the…

Quantum Physics · Physics 2025-09-12 Peng Chen , Jun Jing

We propose a spin-motion state for high-precision quantum metrology with super-Heisenberg scaling of the parameter estimation uncertainty using a trapped ion system. Such a highly entangled state can be created using the Tavis-Cummings…

Quantum Physics · Physics 2024-11-18 Venelin P. Pavlov , Peter A. Ivanov

Continuous variables systems find valuable applications in quantum information processing. To deal with an infinite-dimensional Hilbert space, one in general has to handle large numbers of discretized measurements in tasks such as…

Entangled quantum probes can achieve Heisenberg-limited measurement precision, but this advantage is typically destroyed by noise. We address this issue by introducing a framework that we call encoded quantum signal processing, which…

Quantum Physics · Physics 2026-03-25 Carlos Ortiz Marrero , Rui Jie Tang , Nathan Wiebe

Balancing high sensitivity with a broad dynamic range is a fundamental challenge in measurement science, as improving one often compromises the other. While traditional quantum metrology has prioritized enhancing local sensitivity, a large…

Quantum Physics · Physics 2025-07-25 Qi Liu , Ming Xue , Matthew Radzihovsky , Xinwei Li , Denis V. Vasilyev , Ling-Na Wu , Vladan Vuletić

We show that it is possible to perform Heisenberg-limited metrology on GHZ-like states, in the presence of generic spatially local, possibly strong interactions during the measurement process. An explicit protocol, which relies on…

Quantum Physics · Physics 2024-04-03 Chao Yin , Andrew Lucas

One of the fundamental problems of quantum statistical physics is how an ideally isolated quantum system can ever reach thermal equilibrium behavior despite the unitary time evolution of quantum-mechanical systems. Here, we study, via…

Quantum Physics · Physics 2025-06-24 Marvin Lenk , Sayak Biswas , Anna Posazhennikova , Johann Kroha

Achieving the ultimate quantum precision in the estimation of multiple physical parameters simultaneously is a challenge in quantum metrology due to fundamental limitations and experimental challenges in harnessing the necessary quantum…

Quantum Physics · Physics 2025-06-24 Atmadev Rai , Danilo Triggiani , Paolo Facchi , Vincenzo Tamma

Quantum thermalization occurs in a broad class of systems from elementary particles to complex materials. Out-of-equilibrium quantum systems have long been understood to either thermalize or retain memory of their initial states, but not…

Quantum Physics · Physics 2025-02-20 Luheng Zhao , Prithvi Raj Datla , Weikun Tian , Mohammad Mujahid Aliyu , Huanqian Loh

Distributed quantum sensing uses quantum correlations between multiple sensors to enhance the measurement of unknown parameters beyond the limits of unentangled systems. We describe a sensing scheme that uses continuous-variable…

Quantum Physics · Physics 2018-03-29 Quntao Zhuang , Zheshen Zhang , Jeffrey H. Shapiro

In quantum metrology, entanglement represents a valuable resource that can be used to overcome the Standard Quantum Limit (SQL) that bounds the precision of sensors that operate with independent particles. Measurements beyond the SQL are…