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A hierarchical equations of motion (HEOM) based numerical approach is developed for accurate and efficient evaluation of dynamical observables of strongly correlated quantum impurity systems. This approach is capable of describing…

Strongly Correlated Electrons · Physics 2013-01-28 ZhenHua Li , NingHua Tong , Xiao Zheng , Dong Hou , JianHua Wei , Jie Hu , YiJing Yan

We consider measurement-based quantum computation using the state of a spin-lattice system in equilibrium with a thermal bath and free to evolve under its own Hamiltonian. Any single qubit measurements disturb the system from equilibrium…

Quantum Physics · Physics 2009-09-23 David Jennings , Andrzej Dragan , Sean D. Barrett , Stephen D. Bartlett , Terry Rudolph

We present a general method to efficiently design optimal control sequences for non-Markovian open quantum systems, and illustrate it by optimizing the shape of a laser pulse to prepare a quantum dot in a specific state. The optimization of…

Quantum Physics · Physics 2023-07-11 Gerald E. Fux , Eoin P. Butler , Paul R. Eastham , Brendon W. Lovett , Jonathan Keeling

We investigate the quantum equation of motion (qEOM), a hybrid quantum-classical algorithm for computing excitation properties of a fermionic many-body system, with a particular emphasis on the strong-coupling regime. The method is designed…

Nuclear Theory · Physics 2023-09-20 Manqoba Q. Hlatshwayo , John Novak , Elena Litvinova

Generalized quantum impurity models -- which feature a few localized and strongly-correlated degrees of freedom coupled to itinerant conduction electrons -- describe diverse physical systems, from magnetic moments in metals to…

Strongly Correlated Electrons · Physics 2024-10-23 Jonas B. Rigo , Andrew K. Mitchell

Impurity Hamiltonians are systems of $N$ fermionic modes where $O(1)$ of them interact among themselves via quartic (or higher order) fermion terms, while coupling quadratically with $O(N)$ bath modes. Without the quartic interactions,…

Quantum Physics · Physics 2026-04-10 N. C. Mai Pham , Raul A. Santos

We review a systematic many-body method capable of describing Fermi liquid and Non-Fermi liquid behavior of quantum impurity models at low temperatures on the same footing. The crossover to the high temperature local moment regime is…

Strongly Correlated Electrons · Physics 2007-05-23 J. Kroha , P. Wölfle

Using one-dimensional spin-orbital model as a typical example of quantum spin systems with richer symmetries, we study the effect of an isolated impurity on its low energy dynamics in the gapless phase through bosonization and…

Strongly Correlated Electrons · Physics 2009-10-31 Yu-Wen Lee , Yu-Li Lee

Strongly correlated quantum impurities under periodic driving can exhibit emergent non-Hermitian phenomena, yet a microscopic understanding has been lacking. We introduce an auxiliary-fermion framework that captures the bath's spin-orbit…

Strongly Correlated Electrons · Physics 2025-12-03 Vinayak M. Kulkarni

We describe a resource-efficient approach to studying many-body quantum states on noisy, intermediate-scale quantum devices. We employ a sequential generation model that allows us to bound the range of correlations in the resulting…

Quantum Physics · Physics 2021-03-05 Johannes Borregaard , Matthias Christandl , Daniel Stilck França

We study quantum impurity models as a platform for quantum thermometry. A single quantum spin-1/2 impurity is coupled to an explicit, structured, fermionic thermal environment which we refer to as the environment or bath. We critically…

Quantum Physics · Physics 2023-05-01 George Mihailescu , Steve Campbell , Andrew K. Mitchell

Recent improvements in control of quantum systems make it seem feasible to finally build a quantum computer within a decade. While it has been shown that such a quantum computer can in principle solve certain small electronic structure…

Quantum Physics · Physics 2016-09-27 Bela Bauer , Dave Wecker , Andrew J. Millis , Matthew B. Hastings , M. Troyer

We numerically study the relaxation dynamics of impurity-host systems, focusing on the presence of long-lived metastable states in the non-equilibrium dynamics after an initial excitation of the impurities. In generic systems, an excited…

Mesoscale and Nanoscale Physics · Physics 2024-09-16 Michael Elbracht , Michael Potthoff

In the $0+1$ dimensional imaginary-time path integral formulation of quantum impurity problems, the retarded action encodes the hybridization of the impurity with the bath. In this Article, we explore the computational power of representing…

We consider open many-body systems governed by a time-dependent quantum master equation with short-range interactions. With a generalized Lieb-Robinson bound, we show that the evolution in this very generic framework is quasi-local, i.e.,…

Quantum Physics · Physics 2012-08-10 Thomas Barthel , Martin Kliesch

We conducted quantum simulations of strongly correlated systems using the quantum flow (QFlow) approach, which enables sampling large sub-spaces of the Hilbert space through coupled eigenvalue problems in reduced dimensionality active…

Quantum Physics · Physics 2023-08-09 Karol Kowalski , Nicholas P. Bauman

Microscopically probing quantum many-body systems by resolving their constituent particles is essential for understanding quantum matter. In most physical systems, distinguishing individual particles, such as electrons in solids, or…

We review recent work on continuous quantum phase transitions in impurity models, both with fermionic and bosonic baths - these transitions are interesting realizations of boundary critical phenomena at zero temperature. The models with…

Statistical Mechanics · Physics 2015-06-24 Matthias Vojta

Many-body systems arising in condensed matter physics and quantum optics inevitably couple to the environment and need to be modelled as open quantum systems. While near-optimal algorithms have been developed for simulating many-body…

Quantum Physics · Physics 2025-09-09 Xie-Hang Yu , Hongchao Li , J. Ignacio Cirac , Rahul Trivedi

Describing dynamics of a quantum system coupled to a complex many-body environment is a ubiquitous problem in quantum science. General non-Markovian environments are characterized by their influence matrix~(IM) -- a multi-time tensor…

Quantum Physics · Physics 2024-08-06 Ilia A. Luchnikov , Michael Sonner , Dmitry A. Abanin