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We explore in a rigorous manner the intuitive connection between the non-Markovianity of the evolution of an open quantum system and the performance of the system as a quantum memory. Using the paradigmatic case of a two-level open quantum…

Quantum Physics · Physics 2017-08-14 Margarida Hinarejos , Mari-Carmen Bañuls , Armando Pérez , Inés de Vega

We investigate continuous quantum error correction, comparing performance under a Markovian error model to two distinct non-Markovian models. The first non-Markovian model involves an interaction Hamiltonian between the system and an…

Quantum Physics · Physics 2026-03-09 Juan Garcia Nila , Todd A. Brun

Linear regression is a data analysis technique, which is categorized as supervised learning. By utilizing known data, we can predict unknown data. Recently, researchers have explored the use of quantum annealing (QA) to perform linear…

Quantum Physics · Physics 2024-10-14 Asuka Koura , Takashi Imoto , Katsuki Ura , Yuichiro Matsuzaki

The time-convolutionless (TCL) projection operator technique allows a systematic analysis of the non-Markovian quantum dynamics of open systems. We introduce a class of projection superoperators which project the states of the total system…

Quantum Physics · Physics 2007-05-23 Heinz-Peter Breuer , Jochen Gemmer , Mathias Michel

A quantum mechanical system of two coupled rotors (particles constrained to move on a circle) is studied from an open quantum systems point of view. One of the rotors is integrated out and the reduced density operator of the other rotor is…

Quantum Physics · Physics 2025-05-21 V V Sreedhar , Ankit Yadav

We provide a method to describe quantum nonlocality for $n$-qubit systems. By treating the correlation function as an $n$-index tensor, we derive a generalized Bell inequality. Taking generalized Greenberger-Horne-Zeilinger (GHZ) state for…

Quantum Physics · Physics 2021-05-11 Dong Ding , Yingqiu He , Fengli Yan , Ting Gao

We revisit the critical behavior of the sub-ohmic spin-boson model. Analysis of both the leading and subleading terms in the temperature dependence of the inverse static local spin susceptibility at the quantum critical point, calculated…

Strongly Correlated Electrons · Physics 2012-02-14 Stefan Kirchner , Kevin Ingersent , Qimiao Si

This paper is a continuation of our previous paper [8], in which we have studied the dynamics of quantum correlations of two qubits embedded each into its own disordered multiconnected environment. We modeled the environment by random…

Quantum Physics · Physics 2020-05-12 Ekaterina Bratus , Leonid Pastur

Estimating transition rates in open quantum systems is hampered by computing-resource demands that grow rapidly with system size. We present a quantum-simulation framework that enables efficient estimation by recasting the transition rate,…

Quantum Physics · Physics 2025-12-16 Robson Christie , Kyunghyun Baek , Jeongho Bang , Jaewoo Joo

The Koopman operator has become an essential tool for data-driven approximation of dynamical (control) systems, e.g., via extended dynamic mode decomposition. Despite its popularity, convergence results and, in particular, error bounds are…

Optimization and Control · Mathematics 2022-02-16 Feliks Nüske , Sebastian Peitz , Friedrich Philipp , Manuel Schaller , Karl Worthmann

We propose an extension of Quantum Mechanics based on the idea that the underlying "quantum noise" has a non-zero, albeit very small, correlation time $\tau_c$. The standard (non-relativistic) Schrodinger equation is recovered to zeroth…

Quantum Physics · Physics 2017-11-22 Jean-Philippe Bouchaud

In this work we investigate the late-time stationary states of open quantum systems coupled to a thermal reservoir in the strong coupling regime. In general such systems do not necessarily relax to a Boltzmann distribution if the coupling…

Statistical Mechanics · Physics 2013-01-15 Y. Subasi , C. H. Fleming , J. M. Taylor , B. L. Hu

We analyse nonperturbatively signal transmission patterns in Green's functions of interacting quantum fields. Quantum field theory is re-formulated in terms of the nonlinear quantum-statistical response of the field. This formulation…

Quantum Physics · Physics 2008-11-26 L. I. Plimak , S. Stenholm

We consider a class of interacting particle systems in continuous space of non-gradient type, which are reversible with respect to Poisson point processes with constant density. For these models, a rate of convergence was recently obtained…

Probability · Mathematics 2024-01-19 Chenlin Gu , Jean-Christophe Mourrat , Maximilian Nitzschner

We theoretically study the non-Markovian dynamics of qubit systems coupled to nonequilibrium environments with nonstationary and non-Markovian statistical properties. The reduced density matrix of the single qubit system satisfies a closed…

Quantum Physics · Physics 2020-08-04 Xiangji Cai

By means of an adapted mean-field expansion for large fillings $n\gg1$, we study the evolution of quantum fluctuations in the time-dependent Bose-Hubbard model, starting in the superfluid state and approaching the Mott phase by decreasing…

Other Condensed Matter · Physics 2008-04-15 Uwe R. Fischer , Ralf Schützhold , Michael Uhlmann

Regularized Markov Decision Processes serve as models of sequential decision making under uncertainty wherein the decision maker has limited information processing capacity and/or aversion to model ambiguity. With functional approximation,…

Artificial Intelligence · Computer Science 2025-02-11 Jiachen Xi , Alfredo Garcia , Petar Momcilovic

In this work, we study quantum correlations in mixed states. The states studied are modeled by a two-qubit system interacting with its environment via a quantum non demolition (purely dephasing) as well as dissipative type of interaction.…

Quantum Physics · Physics 2011-12-05 Indranil Chakrabarty , Subhashish Banerjee , Nana Siddharth

Quantum phase transition in the one-dimensional period-two and uniform quantum compass model are studied by using the pseudo-spin transformation method and the trace map method. The exact solutions are presented, the fidelity, the…

Strongly Correlated Electrons · Physics 2009-11-13 Ke-Wei Sun , Yu-Yu Zhang , Qing-Hu Chen

We apply algorithms based on Lieb-Robinson bounds to simulate time-dependent and thermal quantities in quantum systems. For time-dependent systems, we modify a previous mapping to quantum circuits to significantly reduce the computer…

Quantum Physics · Physics 2009-11-13 M. B. Hastings