Decoherence decay time and thermal distributions for quadratic quantum Lagrangians

2018 ◽  
Vol 96 (10) ◽  
pp. 1138-1144
Author(s):  
Zahra Musavi
Keyword(s):  
High Temperature ◽  
Quantum System ◽  
Wigner Function ◽  
Decay Time ◽  
Weak Coupling ◽  
Distribution Functions ◽  
Weak Coupling Regime ◽  
Thermal Distribution ◽  
Quantum Propagator ◽  
External Forces

Quantum propagator for a general quadratic Lagrangian is obtained using position and momentum operators in Heisenberg picture and properties of propagators. For a quantum system governed by a general quadratic Lagrangian containing external forces, decoherence decay time, thermal distribution functions, and thermal Wigner function are obtained in high temperature and weak coupling regime.

scholarly journals ON THE WEAK-COUPLING LIMIT FOR BOSONS AND FERMIONS

2005 ◽  
Vol 15 (12) ◽  
pp. 1811-1843 ◽  
Author(s):  
D. BENEDETTO ◽  
M. PULVIRENTI ◽  
F. CASTELLA ◽  
R. ESPOSITO
Keyword(s):  
Boltzmann Equation ◽  
Wigner Function ◽  
Weak Coupling ◽  
Convergence Result ◽  
Weak Coupling Limit ◽  
Perturbative Expansion ◽  
Weak Coupling Regime ◽  
Interacting Particles ◽  
The One ◽  
Bose Einstein

In this paper we consider a large system of bosons or fermions. We start with an initial datum which is compatible with the Bose–Einstein, respectively Fermi–Dirac, statistics. We let the system of interacting particles evolve in a weak-coupling regime. We show that, in the limit, and up to the second order in the potential, the perturbative expansion expressing the value of the one-particle Wigner function at time t, agrees with the analogous expansion for the solution to the Uehling–Uhlenbeck equation. This paper follows the same spirit as the companion work,2 where the authors investigated the weak-coupling limit for particles obeying the Maxwell–Boltzmann statistics: here, they proved a (much stronger) convergence result towards the solution of the Boltzmann equation.

Shared-mode assisted resonant energy transfer in the weak coupling regime

2009 ◽  
Vol 130 (21) ◽  
pp. 214505 ◽  
Author(s):  
E. Hennebicq ◽  
D. Beljonne ◽  
C. Curutchet ◽  
G. D. Scholes ◽  
R. J. Silbey
Keyword(s):  
Energy Transfer ◽  
Weak Coupling ◽  
Weak Coupling Regime ◽  
Resonant Energy ◽  
Resonant Energy Transfer

Transition from strong to weak coupling regime with lowering Tc in Tl2Ba2CuO6+x

1994 ◽  
Vol 235-240 ◽  
pp. 1613-1614
Author(s):  
O.M. Vyaselev ◽  
N.N. Kolesnikov ◽  
I.F. Schegolev
Keyword(s):  
Weak Coupling ◽  
Weak Coupling Regime

Anomalies in Strongly Coupled Harmonic Quantum Brownian Motion

2013 ◽  
Vol 20 (01) ◽  
pp. 1350002 ◽  
Author(s):  
F. Giraldi ◽  
F. Petruccione
Keyword(s):  
Time Evolution ◽  
Power Law ◽  
Weak Coupling ◽  
Inverse Power ◽  
Strong Coupling Regime ◽  
Weak Coupling Regime ◽  
Spectral Densities ◽  
Inverse Power Law ◽  
Critical Configurations ◽  
Long Time

The exact dynamics of a quantum damped harmonic oscillator coupled to a reservoir of boson modes has been formally described in terms of the coupling function, both in weak and strong coupling regime. In this scenario, we provide a further description of the exact dynamics through integral transforms. We focus on a special class of spectral densities, sub-ohmic at low frequencies, and including integrable divergencies referred to as photonic band gaps. The Drude form of the spectral densities is recovered as upper limit. Starting from special distributions of coherent states as external reservoir, the exact time evolution, described through Fox H-functions, shows long time inverse power law decays, departing from the exponential-like relaxations obtained for the Drude model. Different from the weak coupling regime, in the sub-ohmic condition, undamped oscillations plus inverse power law relaxations appear in the long time evolution of the observables position and momentum. Under the same condition, the number of excitations shows trapping of the population of the excited levels and oscillations enveloped in inverse power law relaxations. Similarly to the weak coupling regime, critical configurations give arbitrarily slow relaxations useful for the control of the dynamics. If compared to the value obtained in weak coupling condition, for strong couplings the critical frequency is enhanced by a factor 4.

Finite-dimensional approximation of the scattering matrix

1986 ◽  
Vol 64 (5) ◽  
pp. 611-616 ◽  
Author(s):  
Helmut Kröger ◽  
Anais Smailagic ◽  
Ralph Girard
Keyword(s):  
Weak Coupling ◽  
Weak Coupling Regime ◽  
S Wave ◽  
Proton Proton ◽  
Time Evolution Operator ◽  
Finite Dimensional Approximation ◽  
Finite Dimensional ◽  
Dimensional Approximation ◽  
S Matrix ◽  
Computer Calculations

A finite-dimensional nonperturbative approximation scheme of the time-evolution operator and the S matrix for relativistic field theories is discussed. It is amenable to computer calculations. Parallels with lattice-field theory are drawn. The method is outlined for the ϕ4 theory. Equivalence to standard perturbation theory in the weak-coupling regime is obtained in the limit of the approximation parameters. The method is tested numerically for nonrelativistic proton–proton s-wave scattering and the the ϕ4 model in the weak-coupling regime in 1 + 1 dimensions. In both examples, convergence to the reference solution is found.

scholarly journals Controllable nonlinearity in a dual-coupling optomechanical system under a weak-coupling regime

2018 ◽  
Vol 97 (3) ◽  
Author(s):  
Gui-Lei Zhu ◽  
Xin-You Lü ◽  
Liang-Liang Wan ◽  
Tai-Shuang Yin ◽  
Qian Bin ◽  
...  
Keyword(s):  
Weak Coupling ◽  
Weak Coupling Regime ◽  
Optomechanical System
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