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We consider an open quantum system in contact with fermionic metallic reservoirs in a nonequilibrium setup. For the case of spin, orbital or potential fluctuations, we present a systematic formulation of real-time renormalization group at…

Mesoscale and Nanoscale Physics · Physics 2014-09-19 Frank Reininghaus , Mikhail Pletyukhov , Herbert Schoeller

An extended variational principle providing the equations of motion for a system consisting of interacting classical, quasiclassical and quantum components is presented, and applied to the model of bilinear coupling. The relevant dynamical…

Quantum Physics · Physics 2009-11-13 M. Grigorescu

We extend the time-dependent variational principle to the setting of dissipative dynamics. This provides a locally optimal (in time) approximation to the dynamics of any Lindblad equation within a given variational manifold of mixed states.…

Quantum Physics · Physics 2013-05-30 Christina V. Kraus , Tobias J. Osborne

We study valence fluctuations at finite temperatures in the extended periodic Anderson model, where the Coulomb interaction between conduction and localized $f$-electrons is taken into account, using dynamical mean-field theory combined…

Strongly Correlated Electrons · Physics 2016-02-17 Ryu Shinzaki , Joji Nasu , Akihisa Koga

We use Monte Carlo simulations to demonstrate generic scaling aspects of classical phase transitions approached through a quench (or annealing) protocol where the temperature changes as a function of time with velocity $v$. Using a…

Statistical Mechanics · Physics 2014-02-25 Cheng-Wei Liu , Anatoli Polkovnikov , Anders W. Sandvik

The dynamic properties of fluid, including density, surface tension, diffusivity and viscosity, are temperature-dependent and can significantly influence the flow dynamics of mesoscopic non-isothermal systems. To capture the correct…

Computational Physics · Physics 2020-07-21 Kaixuan Zhang , Jie Li , Shuo Chen , Yang Liu

We have recently presented an extension of the standard variational calculus to include the presence of deformed derivatives in the Lagrangian of a system of particles and in the Lagrangian density of field-theoretic models. Classical…

Mathematical Physics · Physics 2017-06-30 J. Weberszpil , J. A. Helayël-Neto

Using a Krylov-subspace time evolution algorithm, we simulate the real-time dynamics of translation invariant non-integrable finite spin rings to quite long times with high accuracy. We systematically study the finite-size deviation between…

Quantum Physics · Physics 2025-05-26 Ivo A. Maceira , Andreas M. Läuchli

Methods of quantum nuclear wave-function dynamics have become very efficient in simulating large isolated systems using the time-dependent variational principle (TDVP). However, a straightforward extension of the TDVP to the density matrix…

Chemical Physics · Physics 2015-06-23 Loic Joubert-Doriol , Artur F. Izmaylov

Using exact diagonalization, Monte-Carlo, and mean-field techniques, characteristic temperature scales for ferromagnetic order are discussed for the Ising and the classical anisotropic Heisenberg model on finite lattices in one and two…

Mesoscale and Nanoscale Physics · Physics 2011-04-12 E. Y. Vedmedenko , N. Mikuszeit , T. Stapelfeldt , R. Wieser , M. Potthoff , A. Lichtenstein , R. Wiesendanger

Describing finite-temperature nonequilibrium dynamics of interacting many-particle systems is a notoriously challenging problem in quantum many-body physics. Here we provide an exact solution to this problem for a system of strongly…

Quantum Gases · Physics 2017-05-02 Y. Y. Atas , D. M. Gangardt , I. Bouchoule , K. V. Kheruntsyan

We describe a variational approach to solving Anderson impurity models by means of exact diagonalization. Optimized parameters of a discretized auxiliary model are obtained on the basis of the Peierls-Feynman-Bogoliubov principle. Thereby,…

Strongly Correlated Electrons · Physics 2015-06-26 M. Schüler , C. Renk , T. O. Wehling

A numerical diagonalization technique with canonical Monte-Carlo simulation algorithm is used to study the phase transitions from low temperature (ordered) phase to high temperature (disordered) phase of spinless Falicov-Kimball model on a…

Strongly Correlated Electrons · Physics 2015-03-20 Umesh K. Yadav , T. Maitra , Ishwar Singh

The variational method of coupled Gaussian functions is applied to Bose-Einstein condensates with long-range interactions. The time-dependence of the condensate is described by dynamical equations for the variational parameters. We present…

Quantum Gases · Physics 2010-08-17 Stefan Rau , Jörg Main , Günter Wunner

The search for problems where quantum adiabatic optimization might excel over classical optimization techniques has sparked a recent interest in inducing a finite-temperature spin-glass transition in quasi-planar topologies. We have…

Disordered Systems and Neural Networks · Physics 2018-05-28 Zheng Zhu , Andrew J. Ochoa , Helmut G. Katzgraber

We study the dynamics of a one-dimensional Bose gas at unit filling in both shallow and deep optical lattices and obtain the dynamic structure factor ${S(k,\omega)}$ by monitoring the linear response to a weak probe pulse. We introduce a…

Quantum Gases · Physics 2022-08-24 Mathias Gartner , Ferran Mazzanti , Robert E. Zillich

We use the Bethe Ansatz technique to study dissipative systems experiencing loss. The method allows us to exactly calculate the Liouvillian spectrum. This opens the possibility of analytically calculating the dynamics of a wide range of…

Statistical Mechanics · Physics 2020-04-14 Berislav Buca , Cameron Booker , Marko Medenjak , Dieter Jaksch

The quantum critical regime marks a zone in the phase diagram where quantum fluctuation around the critical point plays a significant role at finite temperatures. While it is of great physical interest, simulation of the quantum critical…

Quantum Physics · Physics 2023-08-09 Zhi-Quan Shi , Xu-Dan Xie , Dan-Bo Zhang

We present a simple and efficient wave function ansatz for the treatment of excited charge-transfer states in real-space quantum Monte Carlo methods. Using the recently-introduced variation-after-response method [J. Chem. Phys. 145, 081103…

Chemical Physics · Physics 2017-11-20 N. S. Blunt , Eric Neuscamman

Dynamical Mean-Field Theory (DMFT) replaces the many-body dynamical problem with one for a single degree of freedom in a thermal bath whose features are determined self-consistently. By focusing on models with soft disordered $p$-spin…

Disordered Systems and Neural Networks · Physics 2020-09-02 Ada Altieri , Giulio Biroli , Chiara Cammarota