Thermodynamics and Dynamics of Bose condensation in a quasi-homogeneous gas

We present an experimental study of the thermodynamics and dynamics of Bose-Einstein condensation (BEC) in an optical-box trap. We first characterize the critical point for BEC, and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. We also observed the quantum Joule-Thomson effect, namely isoenthalpic cooling of a non-interacting gas [1]. We then investigate the dynamics of Bose condensation in the box potential following a rapid temperature quench through the phase transition, and focus on the time-evolution of the condensed fraction, the coherence length and the mean-field shift, that we probe via Bragg spectroscopy. \\[4pt] [1] T.F. Schmidutz, I. Gotlibovych, A.L. Gaunt, R.P. Smith, N. Navon, Z. Hadzibabic, Phys. Rev. Lett. 112, 040403 (2014)