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Time-dependent response and correlation functions are studied in random quantum systems composed of infinitely many parts without mutual interaction and defined with statistically independent random matrices. The latter are taken within the…

Statistical Mechanics · Physics 2025-12-17 Sudhir Ranjan Jain , Pierre Gaspard

Schemes of classical shadows have been developed to facilitate the read-out of digital quantum devices, but similar tools for analog quantum simulators are scarce and experimentally impractical. In this work, we provide a measurement scheme…

Quantum Physics · Physics 2024-12-18 Janek Denzler , Antonio Anna Mele , Ellen Derbyshire , Tommaso Guaita , Jens Eisert

Quantum correlation provides a promising measure beyond entanglement. Here, we propose a necessary and sufficient condition for nonzero quantum correlation in continuous variable systems, which is simple and easy to perform in terms of a…

Quantum Physics · Physics 2015-11-12 Chengjie Zhang , Sixia Yu , Qing Chen , Haidong Yuan , C. H. Lai , C. H. Oh

A quantum-classical limit of the canonical equilibrium time correlation function for a quantum system is derived. The quantum-classical limit for the dynamics is obtained for quantum systems comprising a subsystem of light particles in a…

Statistical Mechanics · Physics 2009-11-10 Alessandro Sergi , Raymond Kapral

The calculation of dynamic response functions is expected to be an early application benefiting from rapidly developing quantum hardware resources. The ability to calculate real-time quantities of strongly-correlated quantum systems is one…

In measurement-based quantum computation (MBQC), local adaptive measurements are performed on the quantum state of a lattice of qubits. Quantum gates are associated with a particular measurement sequence, and one way of viewing MBQC is that…

Quantum Physics · Physics 2009-05-18 Thomas Chung , Stephen D. Bartlett , Andrew C. Doherty

Quantum discord as a measure of the quantum correlations cannot be easily computed for most of density operators. In this paper, we present a measure of the total quantum correlations that is operationally simple and can be computed…

Quantum Physics · Physics 2016-04-19 Javad Behdani , Seyed Javad Akhtarshenas , Mohsen Sarbishaei

We show that one may interpret physical reality as random fields in space-time. These have a probability given by the expectation of a coherent state projection operator, called the Q-function. The resulting dynamical evolution includes…

Quantum Physics · Physics 2020-10-20 Peter D. Drummond , Margaret D. Reid

During a continuous measurement, quantum systems can be described by a stochastic Schr\"odinger equation which, in the appropriate limit, reproduces the von Neumann wave-function collapse. The average behavior on the ensemble of all…

Condensed Matter · Physics 2009-10-30 Carlo Presilla , Ubaldo Tanbini

We investigate the two-points correlation function for several boundary-driven interacting particle systems. Our goal is to show that the time evolution of that correlation function is solution to a partial differential equation that can be…

Probability · Mathematics 2024-10-24 P. Gonçalves , B. Salvador

In this paper, we study the uniform measure for the self-conjugate partitions. We derive the $q$-difference equation which is satisfied by the $n$-point correlation function related to the uniform measure. As applications, we give explicit…

Mathematical Physics · Physics 2026-05-05 Zhiyong Wang , Chenglang Yang

Scrambling unitary dynamics in a quantum system transmutes local quantum information into a non-local web of correlations which manifests itself in a complex spatio-temporal pattern of entanglement. In such a context, we show there can…

Quantum Physics · Physics 2025-06-02 Alan Sherry , Sthitadhi Roy

The fact that quantum mechanics predicts stronger correlations than classical physics is an essential cornerstone of quantum information processing. Indeed, these quantum correlations are a valuable resource for various tasks, such as…

We show how two-point correlation functions derived within non-isotropic random wave models are in fact quantum results that are obtained in the appropriate limit in terms of the exact Green function of the quantum system. Since no…

Chaotic Dynamics · Physics 2007-05-23 J. D. Urbina , K. Richter

Quantum metrology exploits quantum correlations in specially prepared entangled or other non-classical states to perform measurements that exceed the standard quantum limit. Typically though, such states are hard to engineer, particularly…

Quantum Physics · Physics 2019-02-05 Lewis A. Clark , Adam Stokes , Almut Beige

We explore, both analytically and numerically, the quantum dynamics of a many-body free-fermion system subjected to local density measurements. We begin by extending the mapping to the nonlinear sigma-model (NLSM) field theory for the case…

Disordered Systems and Neural Networks · Physics 2026-04-22 Igor Poboiko , Alexander D. Mirlin

Characteristic functions (CFs) provide a very efficient method for evaluating the probability density functions of stochastic thermodynamic quantities and investigating their statistical features in quantum master equations (QMEs). A…

Statistical Mechanics · Physics 2016-12-28 Fei Liu , Jingyi Xi

We present a general formalism based on scattering theory to calculate quantum correlation functions involving several time-dependent current operators. A key ingredient is the causality of the scattering matrix, which allows one to deal…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 J. Salo , F. W. J. Hekking , J. P. Pekola

The claim that there is an inconsistency of quantum-classical dynamics [1] is investigated. We point out that a consistent formulation of quantum and classical dynamics which can be used to describe quantum measurement processes is already…

Quantum Physics · Physics 2007-05-23 E. C. G. Sudarshan

We discuss a computer implementation of a recursive formula to calculate correlation functions of descendant states in two-dimensional CFT. This allows us to obtain any $N$-point function of vacuum descendants, or to express the correlator…

High Energy Physics - Theory · Physics 2021-05-24 Enrico M. Brehm , Matteo Broccoli