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We extend the ability of unitary quantum circuits by interfacing it with classical autoregressive neural networks. The combined model parametrizes a variational density matrix as a classical mixture of quantum pure states, where the…

Quantum Physics · Physics 2020-01-16 Jin-Guo Liu , Liang Mao , Pan Zhang , Lei Wang

We present a unified formulation for quantum statistical physics based on the representation of the density matrix as a functional integral. We identify the stochastic variable of the effective statistical theory that we derive as a…

Quantum Physics · Physics 2014-11-18 A. Bessa , C. A. A. de Carvalho , E. S. Fraga

We consider the extension of static dimensional reduction to real-time. For a scalar field theory it is shown that in the high-temperature limit this leads to an effective classical theory. Quantum corrections to the leading classical…

High Energy Physics - Phenomenology · Physics 2007-05-23 Bert-Jan Nauta , Chris van Weert

We demonstrate the power of a first principle-based and practicable method that allows for the perturbative computation of reduced density matrix elements of an open quantum system without making use of any master equations. The approach is…

High Energy Physics - Theory · Physics 2023-06-12 Christian Käding , Mario Pitschmann

For the model of a linearly driven quantum anharmonic oscillator, the role of damping is investigated. We compare the position of the stable points in phase space obtained from a classical analysis to the result of a quantum mechanical…

Quantum Physics · Physics 2012-12-27 Lingzhen Guo , Michael Marthaler , Stephan André , Gerd Schön

We develop a formalism that allows the computation of the quantum effective potential of a scalar order parameter in a class of holographic theories at finite temperature and charge density. The effective potential is a valuable tool for…

High Energy Physics - Theory · Physics 2015-06-05 Elias Kiritsis , Vasilis Niarchos

Effect of replacing the classical game object with a quantum object is analyzed. We find this replacement requires a throughout reformation of the framework of Game Theory. If we use density matrix to represent strategy state of players,…

Quantum Physics · Physics 2007-05-23 Jinshan Wu

We use the quantum action to study the dynamics of quantum system at finite temperature. We construct the quantum action non-perturbatively and find temperature dependent action parameters. Here we apply the quantum action to study quantum…

Quantum Physics · Physics 2016-08-16 L. A. Caron , H. Kröger , X. Q. Luo , G. Melkonyan , K. J. M. Moriarty

In high temperature QCD, the perturbation theory is plagued with infrared divergences which reflect long-range non-perturbative phenomena. I argue that it is possible to study such phenomena within a classical thermal field theory which can…

High Energy Physics - Phenomenology · Physics 2007-05-23 Edmond Iancu

We study a quantum mechanical toy model that mimics some features of a quenched phase transition. Both by virtue of a time-dependent Hamiltonian or by changing the temperature of the bath we are able to show that even after classicalization…

Quantum Physics · Physics 2009-11-07 Nuno D. Antunes , Fernando C. Lombardo , Diana Monteoliva

A master equation for the deformed quantum harmonic oscillator interacting with a dissipative environment, in particular with a thermal bath, is derived in the microscopic model by using perturbation theory, for the case when the…

Quantum Physics · Physics 2009-11-13 A. Isar , W. Scheid

Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical…

Chemical Physics · Physics 2015-12-09 Anders M. N. Niklasson , Marc J. Cawkwell , Emanuel H. Rubensson , Elias Rudberg

Today it still remains a challenge whether quantum mechanics has an underlying statistical explanation or not. While there are and were a lot of models trying to explain quantum phenomena with statistical methods these all failed on certain…

Quantum Physics · Physics 2016-12-05 Gabor Helesfai

We construct an effective action for QCD by expanding the quark determinant in powers of the chemical potential at finite temperature in the case of massless quarks. To cut the infinite series we adopt the Weinberg power counting criteria.…

High Energy Physics - Phenomenology · Physics 2010-04-29 E. S. Fraga , C. Villavicencio

We present a variational density matrix approach to the thermal properties of interacting fermions in the continuum. The variational density matrix is parametrized by a permutation equivariant many-body unitary transformation together with…

Strongly Correlated Electrons · Physics 2022-04-04 Hao Xie , Linfeng Zhang , Lei Wang

The non-commutativity of the position and momentum operators is formulated as an effective potential in classical phase space and expanded as a series of successive many-body terms, with the pair term being dominant. A non-linear partial…

Quantum Physics · Physics 2020-08-11 Phil Attard

We demonstrate the feasibility of a nonperturbative analysis of quantum field theory in the worldline formalism with the help of an efficient numerical algorithm. In particular, we compute the effective action for a super-renormalizable…

High Energy Physics - Theory · Physics 2009-11-11 H. Gies , J. Sánchez--Guillén , R. A. Vázquez

In these notes we review some properties of Statistical Quantum Field Theory at equilibrium, i.e Quantum Field Theory at finite temperature. We explain the relation between finite temperature quantum field theory in (d,1) dimensions and…

High Energy Physics - Phenomenology · Physics 2007-05-23 J. Zinn-Justin

Based on standard field-theoretic considerations, we develop an effective action approach for investigating quantum phase transitions in lattice Bose systems at arbitrary temperature. We begin by adding to the Hamiltonian of interest a…

Statistical Mechanics · Physics 2009-01-20 Barry Bradlyn , Francisco Ednilson A. dos Santos , Axel Pelster

We utilize lattice simulations of the dimensionally reduced effective field theory (EQCD) to determine the quark number susceptibility of QCD at high temperature ($T>2T_c$). We also use analytic continuation to obtain results at finite…

High Energy Physics - Lattice · Physics 2008-11-26 Ari Hietanen , Kari Rummukainen