Spontaneous creation of Kibble-Zurek solitons in a Bose-Einstein condensate

Giacomo Lamporesi, Simone Donadello, Simone Serafini +2 more

Gor Nikoghosyan, Adolfo del Campo, Alex Retzker +1 more

M.A. van Gogh

We study the formation of defects in a Bose-Einstein condensate as is described by the Kibble-Zurek mechanism. The mechanism describes the formation of defects when a second order phase transition is crossed at a finite rate. This is done by shock cooling or quenching the last part of the evaporative cooling process where the transition into the condensed state is made. This allows for the study of the amount of solitons formed as a function of the quench time with the ultimate goal of determining the critical exponents of the phase transition. The amount of solitons is predicted by the Kibble-Zurek mechanism to scale as the quench time to the power alpha, which we attempted to measure. The dynamics of solitons are also studied in order to determine the time scale on which they decay. This turns out to be in the order of 0.29 seconds, and thus an important factor, since we consider quench times in the order of seconds. When correcting for the decay on this timescale, it turns out that alpha is extremely sensitive to variations in the decay time and therefore we were not able to give conclusive evidence on a value for the exponent. Instead we estimate the value of alpha to be between 0.5 and 2, based on our measurements.

Seong-Ho Shinn, Matteo Massaro, Thudiyangal Mithun +1 more

The Kibble-Zurek mechanism (KZM) predicts the spontaneous formation of topological defects in a continuous phase transition driven at a finite rate. We propose the generation of spontaneous quantum turbulence (SQT) via the KZM during Bose-Einstein condensation induced by a thermal quench. Using numerical simulations of the stochastic projected Gross-Pitaevskii equation in two spatial dimensions, we describe the formation of a newborn Bose-Einstein condensate proliferated by quantum vortices. We establish the nonequilibrium universality of SQT through the Kibble-Zurek and Kolmogorov scaling of the incompressible kinetic energy.

G. M. Lee, Simon A. Haine, Matthew J. Davis

Hiroki Saito, Yuki Kawaguchi, Masahito Ueda

It is shown that spin vortices are created through the Kibble-Zurek mechanism in the quantum phase transition of a spin-1 ferromagnetic Bose-Einstein condensate when the applied magnetic field is quenched to below a critical value. It is also shown that the spin correlation functions have finite correlation lengths, and that the magnetization at widely separated positions grows in random directions, resulting in spontaneous creation of spin vortices. We numerically confirm the scaling laws that the winding number of spin vortices is proportional to the square root of the length of a closed path and, for a slow quench, is proportional to ${\ensuremath{\tau}}_{\text{Q}}^{\ensuremath{-}1∕6}$ with ${\ensuremath{\tau}}_{\text{Q}}$ being the quench time. The relevance of spin conservation to the Kibble-Zurek mechanism is discussed.