scholarly journals The multi-flavor Schwinger model with chemical potential - Overcoming the sign problem with Matrix Product States

2017 ◽  
Author(s):  
Stefan Kühn ◽  
Mari Carmen Banuls ◽  
Krzysztof Cichy ◽  
J. Ignacio Cirac ◽  
Karl Jansen ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Matrix Product ◽  
Matrix Product States ◽  
Schwinger Model ◽  
Sign Problem

scholarly journals Density Induced Phase Transitions in the Schwinger Model: A Study with Matrix Product States

2017 ◽  
Vol 118 (7) ◽  
Author(s):  
Mari Carmen Bañuls ◽  
Krzysztof Cichy ◽  
J. Ignacio Cirac ◽  
Karl Jansen ◽  
Stefan Kühn
Keyword(s):  
Phase Transitions ◽  
Matrix Product ◽  
Matrix Product States ◽  
Schwinger Model

scholarly journals The mass spectrum of the Schwinger model with matrix product states

2013 ◽  
Vol 2013 (11) ◽  
Author(s):  
M.C. Bañuls ◽  
K. Cichy ◽  
J.I. Cirac ◽  
K. Jansen
Keyword(s):  
Mass Spectrum ◽  
Matrix Product ◽  
Matrix Product States ◽  
Schwinger Model

scholarly journals Temperature dependence of the chiral condensate in the Schwinger model with Matrix Product States

2015 ◽  
Author(s):  
Hana Saito ◽  
Mari Carmen Banuls ◽  
Krzysztof Cichy ◽  
J. Ignacio Cirac ◽  
Karl Jansen
Keyword(s):  
Temperature Dependence ◽  
Chiral Condensate ◽  
Matrix Product ◽  
Matrix Product States ◽  
Schwinger Model

scholarly journals Thermal evolution of the 1-flavour Schwinger model with using Matrix Product States

2016 ◽  
Author(s):  
Hana Saito ◽  
Mari Carmen Banuls ◽  
Krzysztof Cichy ◽  
J. Ignacio Cirac ◽  
Karl Jansen
Keyword(s):  
Thermal Evolution ◽  
Matrix Product ◽  
Matrix Product States ◽  
Schwinger Model

scholarly journals Optimal sampling of dynamical large deviations via matrix product states

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Luke Causer ◽  
Mari Carmen Bañuls ◽  
Juan P. Garrahan
Keyword(s):  
Large Deviations ◽  
Matrix Product ◽  
Optimal Sampling ◽  
Matrix Product States

scholarly journals Complex Langevin calculations in QCD at finite density

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Yuta Ito ◽  
Hideo Matsufuru ◽  
Yusuke Namekawa ◽  
Jun Nishimura ◽  
Shinji Shimasaki ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Chemical Potential ◽  
Expansion Method ◽  
Finite Density ◽  
Fermi Sphere ◽  
Expectation Value ◽  
Sign Problem ◽  
Zero Momentum ◽  
Effective Theories ◽  
Severe Sign

Abstract We demonstrate that the complex Langevin method (CLM) enables calculations in QCD at finite density in a parameter regime in which conventional methods, such as the density of states method and the Taylor expansion method, are not applicable due to the severe sign problem. Here we use the plaquette gauge action with β = 5.7 and four-flavor staggered fermions with degenerate quark mass ma = 0.01 and nonzero quark chemical potential μ. We confirm that a sufficient condition for correct convergence is satisfied for μ/T = 5.2 − 7.2 on a 83 × 16 lattice and μ/T = 1.6 − 9.6 on a 163 × 32 lattice. In particular, the expectation value of the quark number is found to have a plateau with respect to μ with the height of 24 for both lattices. This plateau can be understood from the Fermi distribution of quarks, and its height coincides with the degrees of freedom of a single quark with zero momentum, which is 3 (color) × 4 (flavor) × 2 (spin) = 24. Our results may be viewed as the first step towards the formation of the Fermi sphere, which plays a crucial role in color superconductivity conjectured from effective theories.

scholarly journals Using Matrix-Product States for Open Quantum Many-Body Systems: Efficient Algorithms for Markovian and Non-Markovian Time-Evolution

Entropy ◽  
2020 ◽  
Vol 22 (9) ◽  
pp. 984
Author(s):  
Regina Finsterhölzl ◽  
Manuel Katzer ◽  
Andreas Knorr ◽  
Alexander Carmele
Keyword(s):  
Time Evolution ◽  
Nearest Neighbor ◽  
Matrix Product ◽  
Body System ◽  
Many Body ◽  
Initial State ◽  
Matrix Product States ◽  
Open Quantum ◽  
Many Body Systems ◽  
The Many

This paper presents an efficient algorithm for the time evolution of open quantum many-body systems using matrix-product states (MPS) proposing a convenient structure of the MPS-architecture, which exploits the initial state of system and reservoir. By doing so, numerically expensive re-ordering protocols are circumvented. It is applicable to systems with a Markovian type of interaction, where only the present state of the reservoir needs to be taken into account. Its adaption to a non-Markovian type of interaction between the many-body system and the reservoir is demonstrated, where the information backflow from the reservoir needs to be included in the computation. Also, the derivation of the basis in the quantum stochastic Schrödinger picture is shown. As a paradigmatic model, the Heisenberg spin chain with nearest-neighbor interaction is used. It is demonstrated that the algorithm allows for the access of large systems sizes. As an example for a non-Markovian type of interaction, the generation of highly unusual steady states in the many-body system with coherent feedback control is demonstrated for a chain length of N=30.

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