[Zurück]

I. Mazets, H.-J. Schmiedmayer:
"Thermalization in a quasi-one-dimensional ultracold bosonic gas";
New Journal of Physics, 12 (2010), 055023; S. 1 - 19.

We study the collisional processes that can lead to thermalization in
one-dimensional (1D) systems. For two-body collisions, excitations of transverse
modes are the prerequisite for energy exchange and thermalization. At very
low temperatures, excitations of transverse modes are exponentially suppressed,
thermalization by two-body collisions stops and the system should become
integrable. In quantum mechanics, virtual excitations of higher radial modes are
possible. These virtually excited radial modes give rise to effective three-body
velocity-changing collisions, which lead to thermalization. We show that these
three-body elastic interactions are suppressed by pairwise quantum correlations
when approaching the strongly correlated regime. If the relative momentum k
is small compared with the two-body coupling constant c, the three-particle
scattering state is suppressed by a factor of (k/c)¹², which is proportional to γ⁻¹², that is, to the square of the three-body correlation function at zero distance
in the limit of the Lieb-Liniger parameter γ >> 1. This demonstrates that in 1D
quantum systems, it is not the freeze-out of two-body collisions but the strong
quantum correlations that ensure absence of thermalization on experimentally
relevant time scales.

http://dx.doi.org/10.1088/1367-2630/12/5/055023

http://publik.tuwien.ac.at/files/PubDat_187432.pdf