I will present our recent work on the experimental realisation of Bose-Einstein condensation in a quasi-uniform box potential [1]. We characterized the critical point for BEC, and observed 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 [2]. In the limit of low temperatures, we measured via Bragg spectroscopy the Heisenberg-limited momentum distribution of the ground state, consistent with a fully coherent macroscopic BEC spanning the whole box [3]. 

 

Finally I will present our latest efforts to address the dynamics of Bose condensation following a rapid temperature quench through the phase transition. Using homodyne matter-wave interferometry we have observed the homogeneous Kibble-Zurek power-law scaling of coherence length with quench time, which allowed us to extract the dynamical critical exponent of that universality class [4].

 

[1] A.L. Gaunt, et. al., Phys. Rev. Lett. 110, 200406 (2013)

[2] T.F. Schmidutz, et. al, Phys. Rev. Lett. 112, 040403 (2014)

[3] I. Gotlibovych, et al. Phys. Rev. A 89, 061604 (2014)

[4] NN et al., arXiv:1410.8487 (2014)