# Decay of a quantum vortex: test of non-equilibrium theories for warm Bose-Einstein condensates - Condensed Matter > Quantum Gases

Abstract: The decay of a vortex from a non-rotating high temperature Bose-Einsteincondensate BEC is modeled using the stochastic projected Gross-Pitaevskiiequation SPGPE. In order to exploit the tunability of temperature in SPGPEtheory while maintaining the total atom number constant, we develop a simpleand accurate Hartree-Fock method to estimate the SPGPE parameters for systemsclose to thermal equilibrium. We then calculate the lifetime of a vortex usingthree classical field theories that describe vortex decay in different levelsof approximation. The SPGPE theory is shown to give the most completedescription of the decay process, predicting significantly shorter vortexlifetimes than the alternative theories. Using the SPGPE theory to simulatevortex decay for a trapped gas of $5\times 10^5$ $^{87}$Rb atoms, we calculatea vortex lifetime $\bar{t}$ that decreases linearly with temperature, fallingin the range 20{ m s}$>\bar{t} >$1.5{ m s} corresponding to the temperaturerange $0.78T c\leq T\leq0.93T c$. The vortex lifetimes calculated provide alower bound for the lifetime of a persistent current with unit winding numberin our chosen trap geometry, in the limit of vanishing vortex pinningpotential.

Author: S. J. Rooney, A. S. Bradley, P. B. Blakie

Source: https://arxiv.org/