Survival of the quantum depletion of a condensate after release from a harmonic trap in theory and experiment.

Measurements of Tan's contact in expanding condensate conflict with predictions of the in situ quantum depletion. It is unclear how the depletion survives without a condensate, and even appears stronger in the far-field than before the trap release. We confirm experimental observations of a power-law decay in the far-field, consistent with the survival of the quantum depletion. Simulations of our experiment support this conclusion and provide a partial explanation. A gap between the numerical and empirical results is an open question obstructing studies of quantum depletion in the far field.