ar X iv : c on d - m at / 9 51 10 58 v 2 2 8 M ar 1 99 6 Phase ordering kinetics of the Bose gas

We study the approach to equilibrium of a Bose gas to a superfluid state. We point out that dynamic scaling, characteristic of far from equilibrium phaseordering systems, should hold. We stress the importance of a non-dissipative Josephson precession term in driving the system to a new universality class. A model of coarsening in dimension d = 2, involving a quench between two temperatures below the equilibrium superfluid transition temperature (Tc), is exactly solved and demonstrates the relevance of the Josephson term. Numerical results on quenches from above Tc in d = 2, 3 provide evidence for the scaling picture postulated. Typeset using REVTEX