Condensation dynamics in a quantum-quenched Bose gas
  By quenching the strength of interactions in a partially condensed Bose gas we create a "super-saturated" vapor which has more thermal atoms than it can contain in equilibrium. Subsequently, the number of condensed atoms ($N_0$) grows even though the temperature ($T$) rises and the total atom number decays. We show that the non-equilibrium evolution of the system is isoenergetic and for small initial $N_0$ observe a clear separation between $T$ and $N_0$ dynamics, thus explicitly demonstrating the theoretically expected "two-step" picture of condensate growth. For increasing initial $N_0$ values we observe a crossover to classical relaxation dynamics. The size of the observed quench-induced effects can be explained using a simple equation of state for an interacting harmonically-trapped atomic gas. 
Robert P. Smith, Scott Beattie, Stuart Moulder, Robert L. D. Campbell,   Zoran Hadzibabic
cond-mat.quant-gas cond-mat.stat-mech physics.atom-ph quant-ph