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Understanding the influence of measurements on the properties of many-body systems is a fundamental problem in quantum mechanics and for quantum technologies. This paper explores how a finite density of stochastic local measurement modifies…

Quantum Physics · Physics 2024-12-25 Alessio Paviglianiti , Xhek Turkeshi , Marco Schirò , Alessandro Silva

Despite recent extensive studies of the non-Hermitian topology, understanding interaction effects is left as a crucial question. In this paper, we address interaction effects on exceptional points which are protected by the non-trivial…

Mesoscale and Nanoscale Physics · Physics 2023-02-16 Tsuneya Yoshida , Yasuhiro Hatsugai

Non-Hermitian systems with parity-time ($\mathcal{PT}$) symmetry give rise to exceptional points (EPs) with exceptional properties that arise due to the coalescence of eigenvectors. Such systems have been extensively explored in the…

Projective measurement, a basic operation in quantum mechanics, can induce seemingly nonlocal effects. In this work, we analyze such effects in many-body systems by studying the non-equilibrium dynamics of weakly monitored quantum circuits,…

Statistical Mechanics · Physics 2024-06-19 Shengqi Sang , Zhi Li , Timothy H. Hsieh , Beni Yoshida

Exceptional points (EPs), the degeneracy point of non-Hermitian systems, have recently attracted great attention after its ability to greatly enhance the sensitivity of micro-cavities is demonstrated experimentally. Unlike the usual…

Quantum Physics · Physics 2021-08-04 Geng-Li Zhang , Di Liu , Xi-Ming Wang , Man-Hong Yung

The so called bipartite non-signaling boxes are systems whose statistics is constrained solely by the principle of no instantaneous signaling between distant locations. Such systems can exhibit much stronger correlations than those admitted…

Quantum Physics · Physics 2018-09-25 Łukasz Czekaj , Michał Horodecki , Tomasz Tylec

Unconventional properties of non-Hermitian systems, such as the existence of exceptional points, have recently been suggested as a resource for sensing. The impact of noise and utility in quantum regimes however remains unclear. In this…

Quantum Physics · Physics 2018-10-18 Hoi-Kwan Lau , Aashish A. Clerk

The competition between unitary quantum dynamics and dissipative stochastic effects, as emerging from continuous-monitoring processes, can culminate in measurement-induced phase transitions. Here, a many-body system abruptly passes, when…

Statistical Mechanics · Physics 2025-02-04 Moritz Eissler , Igor Lesanovsky , Federico Carollo

State-of-the-art quantum simulators permit local temporal control of interactions and midcircuit readout. These capabilities open the way towards the exploration of intriguing nonequilibrium phenomena. We illustrate this with a kinetically…

Quantum Physics · Physics 2025-06-12 Marcel Cech , María Cea , Mari Carmen Bañuls , Igor Lesanovsky , Federico Carollo

Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been…

We present a theoretical study of the relationship between entanglement and entropy in multi-qubit quantum optical systems. Specifically we investigate quantitative relations between the concurrence and linear entropy for a two-qubit mixed…

Quantum Physics · Physics 2009-11-10 Alexandra Olaya-Castro , Neil F. Johnson , Luis Quiroga

The state of a quantum system may be steered towards a predesignated target state, employing a sequence of weak $\textit{blind}$ measurements (where the detector's readouts are traced out). Here we analyze the steering of a two-level system…

Quantum Physics · Physics 2022-01-19 Parveen Kumar , Kyrylo Snizhko , Yuval Gefen , Bernd Rosenow

Decoherence of a quantum system (which then starts to display classical features) results from the interaction of the system with the environment, and is well described in the framework of the theory of continuous quantum measurements…

Quantum Physics · Physics 2010-12-17 Michael B. Mensky

Exceptional points, a remarkable phenomenon in physical systems, have been exploited for sensing applications. It has been demonstrated recently that it can also utilize as sensory threshold in which the interplay between exceptional-point…

Applied Physics · Physics 2024-10-18 Shirin Panahi , Li-Li Ye , Ying-Cheng Lai

The nontrivial degeneracies in non-Hermitian systems, exceptional points (EPs), have attracted extensive attention due to intriguing phenomena. Compared with commonly observed second-order EPs, high-order EPs show rich physics due to their…

Quantum Physics · Physics 2024-12-16 Yue Li , Yang Wu , Yuqi Zhou , Mengxiang Zhang , Xingyu Zhao , Yibo Yuan , Xu Cheng , Yi Li , Xi Qin , Xing Rong , Yiheng Lin , Jiangfeng Du

Interspersing unitary dynamics with local measurements results in measurement-induced phases and transitions in many-body quantum systems. When the evolution is driven by a local Hamiltonian, two types of transitions have been observed,…

Quantum Physics · Physics 2024-02-23 Bo Xing , Xhek Turkeshi , Marco Schiró , Rosario Fazio , Dario Poletti

We study the asymptotic bipartite entanglement entropy of the quantum trajectories of a free-fermionic system, when subject to a continuous nonlocal monitoring. The measurements are described by Gaussian-preserving two-point operators,…

Quantum Physics · Physics 2023-09-20 Angelo Russomanno , Giulia Piccitto , Davide Rossini

Quantum metrology based on quantum entanglement and quantum coherence improves the accuracy of measurement. In this paper, we briefly review the schemes of quantum metrology in various complex systems, including non-Markovian noise,…

Quantum Physics · Physics 2024-01-18 Qing Ai , Yang-Yang Wang , Jing Qiu

Complex spectra of dissipative quantum systems may exhibit degeneracies known as exceptional points (EPs). At these points the systems' dynamics may undergo drastic changes. Phenomena associated with EPs and their applications have been…

Quantum Physics · Physics 2025-03-19 Andrei I. Pavlov , Yuval Gefen , Alexander Shnirman

In this manuscript, working with a binary mechanical system, we examine the effect of quantum gravity on the exceptional points of the system. On the one side, we find that the exceedingly weak effect of quantum gravity can be sensed via…

Quantum Physics · Physics 2022-01-05 Dianzhen Cui , T. Li , Jianning Li , Xuexi Yi