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The Klein-Kramers equation, governing the Brownian motion of a classical particle in quantum environment under the action of an arbitrary external potential, is derived. Quantum temperature and friction operators are introduced and at large…

Quantum Physics · Physics 2018-06-15 R. Tsekov

Variational quantum eigensolver (VQE) is regarded as a promising candidate of hybrid quantum-classical algorithm for the near-term quantum computers. Meanwhile, VQE is confronted with a challenge that statistical error associated with the…

Quantum Physics · Physics 2023-12-12 Ken N. Okada , Keita Osaki , Kosuke Mitarai , Keisuke Fujii

We study the nonstationary solutions of Fokker-Planck equations associated to either stationary or nonstationary quantum states. In particular we discuss the stationary states of quantum systems with singular velocity fields. We introduce a…

Quantum Physics · Physics 2009-10-31 N. Cufaro Petroni , S. De Martino , S. De Siena , F. Illuminati

We use the Lipkin-Meshkov-Glick (LMG) model and the valence-space nuclear shell model to examine the likely performance of variational quantum eigensolvers in nuclear-structure theory. The LMG model exhibits both a phase transition and…

Nuclear Theory · Physics 2022-06-30 A. M. Romero , J. Engel , Ho Lun Tang , Sophia E. Economou

With the aim of establishing a framework to efficiently perform the practical application of quantum chemistry simulation on near-term quantum devices, we envision a hybrid quantum--classical framework for leveraging problem decomposition…

We investigate a stochastic approach to non-equilibrium quantum spin systems based on recent insights linking quantum and classical dynamics. Exploiting a sequence of exact transformations, quantum expectation values can be recast as…

Statistical Mechanics · Physics 2019-01-31 S. De Nicola , B. Doyon , M. J. Bhaseen

Continuous-time stochastic processes pervade everyday experience, and the simulation of models of these processes is of great utility. Classical models of systems operating in continuous-time must typically track an unbounded amount of…

Quantum Physics · Physics 2018-03-05 Thomas J. Elliott , Mile Gu

We present a variational algorithm for fault tolerant quantum computing to solve a system of linear equations which directly maximises the parameters of the target fidelity. This so-called measurement test algorithm can be applied to any…

Quantum Physics · Physics 2026-04-30 Alain Giresse Tene , Thomas Konrad

In the effort to develop useful quantum computers simulating quantum machines with conventional computing resources is a key capability. Such simulations will always face limits preventing the emulation of quantum computers of substantial…

Quantum Physics · Physics 2023-02-20 Xiaosi Xu , Simon Benjamin , Jinzhao Sun , Xiao Yuan , Pan Zhang

Solving quantum molecular systems presents a significant challenge for classical computation. The advent of early fault-tolerant quantum computing (EFTQC) devices offers a promising avenue to address these challenges, leveraging advanced…

Quantum Physics · Physics 2025-11-10 Yukun Zhang , Xiaoming Zhang , Jinzhao Sun , Heng Lin , Yifei Huang , Dingshun Lv , Xiao Yuan

Identifying and extracting the past information relevant to the future behaviour of stochastic processes is a central task in the quantitative sciences. Quantum models offer a promising approach to this, allowing for accurate simulation of…

Quantum Physics · Physics 2019-06-26 Qing Liu , Thomas. J. Elliott , Felix. C. Binder , Carlo Di Franco , Mile Gu

Open quantum systems play a central role in contemporary nanoscale technologies, including molecular electronics, quantum heat engines, quantum computation and information processing. A major theoretical challenge is to construct dynamical…

Quantum Physics · Physics 2026-02-16 Stefano Giordano , Giuseppe Florio , Giuseppe Puglisi , Fabrizio Cleri , Ralf Blossey

The variational quantum eigensolver is one of the most promising algorithms for near-term quantum computers. It has the potential to solve quantum chemistry problems involving strongly correlated electrons, which are otherwise difficult to…

Quantum Physics · Physics 2023-07-18 Luogen Xu , James K. Freericks

Building on a model recently proposed by F. Calogero, we postulate the existence of a coherent, long--range universal tremor affecting any stable and confined classical dynamical system. Deriving the characteristic fluctuative unit of…

Quantum Physics · Physics 2015-06-26 Salvatore De Martino , Silvio De Siena , F. Illuminati

The variational quantum eigensolver (VQE) is a method that uses a hybrid quantum-classical computational approach to find eigenvalues and eigenvalues of a Hamiltonian. VQE has been proposed as an alternative to fully quantum algorithms such…

Quantum Physics · Physics 2021-09-01 Dmitry A. Fedorov , Bo Peng , Niranjan Govind , Yuri Alexeev

Variational quantum algorithms have been proposed to solve static and dynamic problems of closed many-body quantum systems. Here we investigate variational quantum simulation of three general types of tasks---generalised time evolution with…

Quantum Physics · Physics 2020-07-01 Suguru Endo , Jinzhao Sun , Ying Li , Simon Benjamin , Xiao Yuan

The semiclassically scaled time-dependent multi-particle Schr\"odinger equation describes, inter alia, quantum dynamics of nuclei in a molecule. It poses the combined computational challenges of high oscillations and high dimensions. This…

Numerical Analysis · Mathematics 2020-12-02 Caroline Lasser , Christian Lubich

Quantum simulation provides quantum systems under study with analogous controllable quantum systems and has wide applications from condensed-matter physics to high energy physics and to cosmology. The quantum system of a homogeneous and…

General Relativity and Quantum Cosmology · Physics 2020-01-08 Sang Pyo Kim

We study the quatum to classical transition process in the context of quantum field theory. Extending the influence functional formalism of Feynman and Vernon, we study the decoherence process for self-interacting quantum fields in flat…

General Relativity and Quantum Cosmology · Physics 2009-09-25 Fernando C. Lombardo

We present a quantum algorithm that analyzes time series data simulated by a quantum differential equation solver. The proposed algorithm is a quantum version of the dynamic mode decomposition algorithm used in diverse fields such as fluid…

Quantum Physics · Physics 2024-10-17 Yuta Mizuno , Tamiki Komatsuzaki