On the survival of quantum depletion of a condensate after release from the trap

I will talk about our (and other groups') experimental and theoretical work on trying to understand the high energy tails that are seen after release of a condensate from its trap. How can depletion survive without a condensate, under what conditions,and why does the depletion after expansion appear much stronger than theoretical predictions for the momentum distribution in equilibrium? The effect has been seen experimentally by at least two groups in Palaiseau and Canberra, but the magnitude of the tails does not match theory. And one theory does not match  another. So possibly there is something fun going on.
J. A. Ross, P. Deuar, D. K. Shin, K. F. Thomas, B. M. Henson, S. S. Hodgman, A. G. Truscott arXiv:2103.15283