Quantum quenches in the Hubbard model: Time-dependent mean-field theory and the role of quantum fluctuations

2011 ◽  
Vol 83 (16) ◽  
Author(s):  
Marco Schiró ◽  
Michele Fabrizio
Keyword(s):  
Field Theory ◽  
Hubbard Model ◽  
Mean Field Theory ◽  
Mean Field ◽  
Quantum Fluctuations ◽  
Time Dependent ◽  
Quantum Quenches

COMPREHENSIVE MEAN FIELD THEORY FOR THE HUBBARD MODEL

1992 ◽  
Vol 06 (05n06) ◽  
pp. 731-747 ◽  
Author(s):  
V. JANIŠ ◽  
D. VOLLHARDT
Keyword(s):  
Field Theory ◽  
Energy Transfer ◽  
Hubbard Model ◽  
Entire Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Exact Expression ◽  
Grand Potential ◽  
Input Parameters

We derive an exact expression for the grand potential of the Hubbard model in d=∞ dimensions. By simplifying the energy transfer between up and down spins we obtain a comprehensive mean-field theory for this model. It is (i) thermodynamically consistent in the entire range of input parameters, (ii) conserving and, (iii) exact in several non-trivial limits, e. g. in the free (U→0), atomic (t→0) and Heisenberg (U≫t, n=1) limit.

scholarly journals Effect of weak disorder on the BCS–BEC crossover in a two-dimensional Fermi gas

2017 ◽  
Vol 31 (09) ◽  
pp. 1750066
Author(s):  
Ayan Khan ◽  
B. Tanatar
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Fermi Gas ◽  
Ultracold Fermi Gas ◽  
Condensate Fraction ◽  
Two Dimensional ◽  
Weak Disorder ◽  
Unique Nature

In this paper, we study the two-dimensional (2D) ultracold Fermi gas with weak impurity in the framework of mean-field theory where the impurity is introduced through Gaussian fluctuations. We have investigated the role of the impurity by studying the experimentally accessible quantities such as condensate fraction and equation of state of the ultracold systems. Our analysis reveals that at the crossover, the disorder enhances superfluidity, which we attribute to the unique nature of the unitary region and to the dimensional effect.

Role of molecular bend angle and biaxiality in the stabilization of the twist-bend nematic phase

Soft Matter ◽  
2020 ◽  
Vol 16 (18) ◽  
pp. 4350-4357 ◽  
Author(s):  
Wojciech Tomczyk ◽  
Lech Longa
Keyword(s):  
Field Theory ◽  
Nematic Phase ◽  
Mean Field Theory ◽  
Mean Field ◽  
Structural Features ◽  
Bend Angle ◽  
Nematic Phases

Within mean-field theory for V-shaped molecules, we have investigated how the alteration of a molecule's structural features influence the stabilization of modulated and non-modulated nematic phases.

scholarly journals Regular and chaotic dynamics in time-dependent relativistic mean-field theory

1997 ◽  
Vol 56 (6) ◽  
pp. 6418-6426 ◽  
Author(s):  
D. Vretenar ◽  
P. Ring ◽  
G. Lalazissis ◽  
W. Pöschl
Keyword(s):  
Field Theory ◽  
Chaotic Dynamics ◽  
Mean Field Theory ◽  
Mean Field ◽  
Time Dependent ◽  
Relativistic Mean Field Theory ◽  
Relativistic Mean Field
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