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The not necessarily unitary evolution operator of a finite dimensional quantum system is studied with the help of a projection operators technique. Applying this approach to the Schr\"odinger equation allows the derivation of an alternative…

Quantum Physics · Physics 2018-08-08 V. Semin , F. Petruccione

We develop a new analytical method for solving real time evolution problems of quantum many-body systems. Our approach is a direct generalization of the well-known canonical perturbation theory for classical systems. Similar to canonical…

Strongly Correlated Electrons · Physics 2009-11-13 A. Hackl , S. Kehrein

I review the quantum theory of the electron moving in a random environment. First, the quantum mechanics of individual particles scattered on a random potential is discussed. The quantum-mechanical description is extended to many-body…

Disordered Systems and Neural Networks · Physics 2021-09-13 Václav Janiš

We describe the representation of arbitrary density operators in terms of expectation values of simple projection operators. Two representations are presented which yield non--recursive schemes for experimentally determining the density…

Quantum Physics · Physics 2009-10-28 Ole Steuernagel , John A. Vaccaro

The transformer architecture, known for capturing long-range dependencies and intricate patterns, has extended beyond natural language processing. Recently, it has attracted significant attention in quantum information and condensed matter…

Quantum Physics · Physics 2025-08-08 Lu Wei , Zhian Jia , Yufeng Wang , Dagomir Kaszlikowski , Haibin Ling

Dynamics of a state of interest coupled to a non-Markovian environment is studied for the first time by concatenating the non-Markovian quantum state diffusion (QSD) equation and the Feshbach projection operator partitioning technique. An…

Quantum Physics · Physics 2012-04-05 Jun Jing , Lian-Ao Wu , J. Q. You , Ting Yu

Quantum many-body control is among most challenging problems in quantum science, due to computational complexity of related underlying problems. We propose an efficient approach for solving a class of control problems for many-body quantum…

Quantum Physics · Physics 2024-02-21 I. A. Luchnikov , M. A. Gavreev , A. K. Fedorov

We present the Reduced Operator Approximation: a simple, physically transparent and computationally efficient method of modelling open quantum systems. It employs the Heisenberg picture of the quantum dynamics, which allows us to focus on…

Quantum Physics · Physics 2015-08-06 Agnieszka Werpachowska

We consider a class of quantum dissipative systems governed by a one parameter completely positive maps on a von-Neumann algebra. We introduce a notion of recurrent and metastable projections for the dynamics and prove that the unit…

Operator Algebras · Mathematics 2007-05-23 Anilesh Mohari

This paper is devoted to the description of the evolution of states of quantum many-particle systems within the framework of a one-particle density operator, which enables to construct the kinetic equations in scaling limits in the presence…

Mathematical Physics · Physics 2012-09-07 V. I. Gerasimenko , Zh. A. Tsvir

A common situation in quantum many-body physics is that the underlying theories are known but too complicated to solve efficiently. In such cases one usually builds simpler effective theories as low-energy or large-scale alternatives to the…

Quantum Physics · Physics 2023-09-07 Yongdan Yang , Zongkang Zhang , Xiaosi Xu , Bing-Nan Lu , Ying Li

Quantum systems out of equilibrium are presently a subject of active research, both in theoretical and experimental domains. In this work we consider time-periodically modulated quantum systems which are in contact with a stationary…

Quantum Gases · Physics 2017-12-06 V. Volokitin , A. Liniov , I. Meyerov , M. Hartmann , M. Ivanchenko , P. Hänggi , S. Denisov

One of the defining features of many-body localization is the presence of extensively many quasi-local conserved quantities. These constants of motion constitute a corner-stone to an intuitive understanding of much of the phenomenology of…

Statistical Mechanics · Physics 2018-05-03 M. Goihl , M. Gluza , C. Krumnow , J. Eisert

Estimating physical properties of quantum states from measurements is one of the most fundamental tasks in quantum science. In this work, we identify conditions on states under which it is possible to infer the expectation values of all…

Quantum Physics · Physics 2024-05-01 Cambyse Rouzé , Daniel Stilck França

Efficient characterization of highly entangled multi-particle systems is an outstanding challenge in quantum science. Recent developments have shown that a modest number of randomized measurements suffices to learn many properties of a…

Quantum Physics · Physics 2022-12-13 Katherine Van Kirk , Jordan Cotler , Hsin-Yuan Huang , Mikhail D. Lukin

In this paper, we extend the standard formalism of quantum mechanics to a quantum theory for a total system including one internal measuring apparatus. The internality of the measuring apparatus implies that different decomposition of a…

Quantum Physics · Physics 2012-05-17 Wen-ge Wang

Exactly solvable many-body systems are few and far between, and the utility of approximate methods cannot be overestimated. Entanglement mean field theory is an approximate method to handle such systems. While mean field theories reduce the…

Quantum Physics · Physics 2013-03-06 Aditi Sen De , Ujjwal Sen

Quantum simulators offer a new opportunity for the experimental exploration of non-equilibrium quantum many-body dynamics, which have traditionally been characterized through expectation values or entanglement measures, based on density…

Quantum Physics · Physics 2025-06-27 Zhiguang Yan , Zi-Yong Ge , Rui Li , Yu-Ran Zhang , Franco Nori , Yasunobu Nakamura

We make and generalize the observation that summing of probability amplitudes of a discrete-time quantum walk over partitions of the walking graph consistent with the step operator results in a unitary evolution on the reduced graph which…

Quantum Physics · Physics 2020-04-06 Václav Potoček

In experimentally realistic situations, quantum systems are never perfectly isolated and the coupling to their environment needs to be taken into account. Often, the effect of the environment can be well approximated by a Markovian master…

Quantum Physics · Physics 2019-07-03 Michael J. Hartmann , Giuseppe Carleo