Daniel G. Barci — Page 4

arXiv2000

Universal Transverse Conductance between Quantum Hall Regions and (2+1)D Bosonization

Using bosonization techniques for (2+1)D systems, we show that the transverse conductance for a system with general current interactions, when measured between perfect Hall regions is not renormalized at low temperatures. Our method extends and combines two results we have recently obtained on low dimensional fermionic systems: on the one hand, the relationship between universality of Landauer conductance and universality of bosonization rules for (1+1)D systems, and on the other hand, the universal character of the bosonized topological current associated to a (2+1)D fermionic system with current interaction.

cond-mat.mes-hall↗

arXiv2000

A Nonequilibrium Quantum Field Theory Description of the Bose-Einstein Condensate

We study the detailed out of equilibrium time evolution of a homogeneous Bose-Einstein condensate.We consider a nonrelativistic quantum theory for a self-interacting complex scalar field, immersed in a thermal bath, as an effective microscopic model for the description of the Bose-Einstein condensate. This approach yields the following main results:(i) the interaction between fluctuations proves to be crucial in the mechanism of instability generation; (ii) there are essentially two regimes in the $k$-space, with a crossover for $k^2/2m \sim 2λ|ϕ_0|^2$, where, in our notation, $λ$ is the coupling constant and $|ϕ_0|^2$ is the condensate density; (iii) a set of coupled equations that determines completely the nonequilibrium dynamics of the condensate density as a function of the temperature and of the total density of the gas.

cond-mat.soft↗