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The Fermi-polaron problem of a mobile impurity interacting with fermionic medium emerges in various contexts, ranging from the foundations of Landau's Fermi-liquid theory to electron-exciton interaction in semiconductors, to unusual…

Quantum Gases · Physics 2021-11-02 Pavel E. Dolgirev , Yi-Fan Qu , Mikhail B. Zvonarev , Tao Shi , Eugene Demler

Digital quantum computers offer a promising route for studying complex many-body systems that are otherwise inaccessible by their classical counterparts. Capabilities including mid-circuit measurements and feedback allow for simulating the…

We investigate the motion of an impurity particle injected with finite velocity into an interacting one-dimensional quantum gas. Using large-scale numerical simulations based on matrix product states, we observe and quantitatively analyze…

We study the partition functions of quantum impurity problems in the domain of complex applied bias for its relation to the non-equilibrium current suggested by Fendley, Lesage and Saleur (cond-mat/9510055). The problem is reformulated as a…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 Sergei Skorik

We generalize the recently developed inchworm quantum Monte Carlo method to the full Keldysh contour with forward, backward, and equilibrium branches to describe the dynamics of strongly correlated impurity problems with time dependent…

Strongly Correlated Electrons · Physics 2017-03-07 Andrey E. Antipov , Qiaoyuan Dong , Joseph Kleinhenz , Guy Cohen , Emanuel Gull

The precise measurement of low temperatures is a challenging, important and fundamental task for quantum science. In particular, in-situ thermometry is highly desirable for cold atomic systems due to their potential for quantum simulation.…

We propose a systematic approach to the non-equilibrium dynamics of strongly interacting many-body quantum systems, building upon the standard perturbative expansion in the Coulomb interaction. High order series are derived from the Keldysh…

Strongly Correlated Electrons · Physics 2019-10-16 Corentin Bertrand , Serge Florens , Olivier Parcollet , Xavier Waintal

The fastest possible collective response of a quantum many-body system is related to its excitations at the highest possible energy. In condensed-matter systems, the corresponding timescale is typically set by the Fermi energy. Taking…

The fact that the computational cost of simulating a many-body quantum system on a computer increases with the amount of entanglement has been considered as the major bottleneck for simulating its out-of-equilibrium dynamics. Some aspects…

Statistical Mechanics · Physics 2019-06-12 Jacopo Surace , Marco Piani , Luca Tagliacozzo

The problem of fermion dynamics is studied using the Q-function for fermions. This is a probabilistic phase-space representation, which we express using Majorana operators, so that the phase-space variable is a real antisymmetric matrix. We…

Quantum Physics · Physics 2021-04-27 Ria Rushin Joseph , Laura E C Rosales-Zárate , Peter D Drummond

We expand iterative numerically-exact influence functional path-integral tools and present a method capable of following the nonequilibrium time evolution of subsystems coupled to multiple bosonic and fermionic reservoirs simultaneously.…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 Lena Simine , Dvira Segal

A few exactly solvable interacting quantum many-body problems with impurities were previously reported to exhibit unusual features such as non-localization and absence of backscattering. In this work we consider the use of these integrable…

Mesoscale and Nanoscale Physics · Physics 2011-11-18 Marion Moliner , Peter Schmitteckert

We present a numerically exact steady-state inchworm Monte Carlo method for nonequilibrium quantum impurity models. Rather than propagating an initial state to long times, the method is directly formulated in the steady-state. This…

Strongly Correlated Electrons · Physics 2023-05-17 André Erpenbeck , Emanuel Gull , Guy Cohen

We present an efficient \textit{ab initio} algorithm for quantum dynamics simulations of interacting systems that is based on the conditional decomposition of the many-body wavefunction [Phys. Rev. Lett. 113, 083003 (2014)]. Starting with…

Mesoscale and Nanoscale Physics · Physics 2019-02-27 Guillermo Albareda , Aaron Kelly , Angel Rubio

We develop a discrete fermion approach for modelling the strong interaction of an arbitrary system interacting with continuum electronic reservoirs. The approach is based on a pseudo-fermion decomposition of the continuum bath correlation…

Quantum reservoir computing is a machine learning framework that offers ease of training compared to other quantum neural networks, as it does not rely on gradient-based optimization. Learning is performed in a single step on the output…

Quantum Physics · Physics 2026-02-04 Baptiste Carles , Julien Dudas , Léo Balembois , Julie Grollier , Danijela Marković

We present a numerically exact Inchworm Monte Carlo method for equilibrium multiorbital quantum impurity problems with general interactions and hybridizations. We show that the method, originally developed to overcome the dynamical sign…

Strongly Correlated Electrons · Physics 2020-05-25 Eitan Eidelstein , Emanuel Gull , Guy Cohen

We introduce a numerically exact real-time evolution scheme for quantum impurities in a macroscopically large bath. The algorithm is few-body revealing, namely it identifies the electronic orbitals that can be made inactive (in a trivial…

Strongly Correlated Electrons · Physics 2025-09-26 Yuriel Núñez-Fernández , Maxime Debertolis , Serge Florens

A discussion on the momentum evolution of an impurity interacting via a finite delta potential repulsion with a non-interacting fermionic background gas is presented. It has recently been shown that the momentum evolution of this system…

Quantum Gases · Physics 2016-07-25 Matthew Malcomson

We study particle current and occupation distribution in a recently proposed model for coherent quantum transport. In this model a system connected to mesoscopic Fermi reservoirs (mesoreservoir) is driven out of equilibrium by the action of…

Mesoscale and Nanoscale Physics · Physics 2016-04-26 Shigeru Ajisaka , Felipe Barra