Coherent evolution of a BEC quenched to unitarity

Following recent experimental results [1], we theoretically study the coherent time evolution of a zero-temperature BEC whose scattering length is quenched suddenly towards unitarity. Despite the resonant atom-atom interactions, the condensate does not deplete instantaneously, and this allows us to describe the short-time behavior with a mean-field-like, many-body variational wavefunction. We compute the dynamics of various observables such as the momentum distribution, Tan's contact, density-density correlations, and the final Feshbach molecule fraction (after quenching back to finite scattering length for imaging). The nonequilibrium behavior of the momentum distribution suggests the presence of unexpected subleading terms that are absent in equilibrium.\\[4pt] [1] P. Makotyn, et al, Nat. Phys. {\bf 10}, 116 (2014).