Quenches from finite-temperature ultracold matter

A. Dalgarno, N. Balakrishnan

Qingze Guan, D. Blume, Vincent M. Klinkhamer +3 more

Jacek Dziarmaga, Marek Tylutki

Low-energy physics of quasi-one-dimensional ultracold atomic gases is often described by a gapless Luttinger liquid (LL). It is nowadays routine to manipulate these systems by changing their parameters in time but, no matter how slow the manipulation is, it must excite a gapless system. We study a smooth change of parameters of the LL (a smooth ``quench'') with a variable quench time and find that the excitation energy decays with an inverse power of the quench time. This universal exponent is $\ensuremath{-}2$ at zero temperature and $\ensuremath{-}1$ for slow enough quenches at finite temperature. The smooth quench does not excite beyond the range of validity of the low-energy LL description.

Daniel González-Cuadra, Maciej Lewenstein, A. Bermúdez +3 more

P. Comaron, F. Larcher, F. Dalfovo +1 more

We study the dynamics of a two-dimensional Bose gas after an instantaneous quench of an initially ultracold thermal atomic gas across the Berezinskii-Kosterlitz-Thouless phase transition, confirming via stochastic simulations that the system undergoes phase-ordering kinetics and fulfills the dynamical scaling hypothesis at late-time dynamics. Specifically, we find in that regime the vortex number decaying in time as $\ensuremath{\langle}{N}_{\mathrm{v}}\ensuremath{\rangle}\ensuremath{\propto}{t}^{\ensuremath{-}1}$, consistent with a dynamical critical exponent $z\ensuremath{\approx}2$ for both temperature and interaction quenches. Focusing on finite-size boxlike geometries, we demonstrate that such an observation is within current experimental reach.

Zlatko Papić, Maksym Serbyn, Dmitry A. Abanin