scholarly journals A  reaction network approach to the convergence to equilibrium of quantum Boltzmann equations for Bose gases

Author(s):  
Minh-Binh Tran ◽  
Gheorghe Craciun

When the temperature of a trapped Bose gas is below the Bose-Einstein transition temperature and above absolute zero, the gas is composed of two distinct components: the Bose-Einstein condensate and the  cloud of thermal excitations. The dynamics of the excitations can be  described by  quantum Boltzmann models. We establish a connection between quantum Boltzmann models and chemical reaction networks. We prove that  the  discrete differential equations for these quantum Boltzmann models converge to an equilibrium point. Moreover, this point is unique for all initial conditions that satisfy the same conservation laws. In the proof, we then employ a toric dynamical system approach, similar to the one used to prove the global attractor conjecture, to study the convergence to equilibrium of  quantum kinetic equations, derived in \cite{tran2020boltzmann}.

2005 ◽  
Vol 19 (15) ◽  
pp. 713-720
Author(s):  
YONG-LI MA ◽  
HAICHEN ZHU

Bogoliubov–de Gennes equations (BdGEs) for collective excitations from a trapped Bose–Einstein condensate described by a spatially smooth ground-state wavefunction can be treated analytically. A new class of closed solutions for the BdGEs is obtained for the one-dimensional (1D) and 3D spherically harmonic traps. The solutions of zero-energy mode of the BdGEs are also provided. The eigenfunctions of the excitations consist of zero-energy mode, zero-quantum-number mode and entire excitation modes when the approximate ground state is a background Bose gas sea.


2015 ◽  
Vol 24 (4) ◽  
pp. 343
Author(s):  
Tran Huu Phat ◽  
Le Viet Hoa ◽  
Dang Thi Minh Hue

The Bose - Einstein condensation of ultra - cold Bose gases is studied by means of the Cornwall - Jackiw - Tomboulis effective potential approach in the improved double - bubble approximation which preserves the Goldstone theorem. The phase structure of Bose - Einstein condensate associating with two different types of phase transition is systematically investigated. Its main feature is that the symmetry which was broken at zero temperature gets restore at higher temperature.


2011 ◽  
Vol 25 (13) ◽  
pp. 1737-1746
Author(s):  
TARUN KUMAR ◽  
ARANYA B. BHATTACHERJEE ◽  
MANMOHAN

We study the transmission spectra of a Bose Einstein condensate (BEC) confined in an optical lattice interacting with two modes of a cavity via nonlinear two-photon transition. In particular, we show that the one-photon and two-photon cavity transmission spectra of a BEC are different. We found that when the BEC is in the Mott state, the usual normal mode splitting present in the one-photon transition is missing in the two-photon interaction. When the BEC is in the superfluid state, the transmission spectrum shows the usual multiple lorentzian structure. However the separation between the lorentzians for the two-photon case is much larger than that for the one-photon case. This study could form the basis for nondestructive high resolution Rydberg spectroscopy of ultracold atoms or two-photon spectroscopy of a gas of ultracold atomic hydrogen.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ming Wang ◽  
Guo-Liang He

In this paper, we investigate a five-component Gross–Pitaevskii equation, which is demonstrated to describe the dynamics of an F=2 spinor Bose–Einstein condensate in one dimension. By employing the Hirota method with an auxiliary function, we obtain the explicit bright one- and two-soliton solutions for the equation via symbolic computation. With the choice of polarization parameter and spin density, the one-soliton solutions are divided into four types: one-peak solitons in the ferromagnetic and cyclic states and one- and two-peak solitons in the polar states. For the former two, solitons share the similar shape of one peak in all components. Solitons in the polar states have the one- or two-peak profiles, and the separated distance between two peaks is inversely proportional to the value of polarization parameter. Based on the asymptotic analysis, we analyze the collisions between two solitons in the same and different states.


Particles ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Brent Harrison ◽  
Andre Peshier

We present a novel numerical scheme to solve the QCD Boltzmann equation in the soft scattering approximation, for the quenched limit of QCD. Using this we can readily investigate the evolution of spatially homogeneous systems of gluons distributed isotropically in momentum space. We numerically confirm that for so-called “overpopulated” initial conditions, a (transient) Bose-Einstein condensate could emerge in a finite time. Going beyond existing results, we analyze the formation dynamics of this condensate. The scheme is extended to systems with cylindrically symmetric momentum distributions, in order to investigate the effects of anisotropy. In particular, we compare the rates at which isotropization and equilibration occur. We also compare our results from the soft scattering scheme to the relaxation time approximation.


2016 ◽  
Vol 30 (09) ◽  
pp. 1650131
Author(s):  
Rukuan Wu ◽  
Yu Shi

In this paper, we analytically find the ground states of a mixture of two species of pseudospin-[Formula: see text] Bose gases with interspecies spin exchange in quite generic parameter regimes. In the most interesting phase, the ground state is strongly entangled between the two species in a very wide parameter regime, and is an entangled Bose-Einstein condensate. The phase diagram and elementary excitations are studied.


2007 ◽  
Vol 98 (17) ◽  
Author(s):  
P. Lugan ◽  
D. Clément ◽  
P. Bouyer ◽  
A. Aspect ◽  
M. Lewenstein ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document