Energy conservation and quantum backreaction in Bose-Einstein condensates

Bose-Einstein condensates are suitable systems for studying fundamental aspects of quantum backreaction. Here, the backreaction problem in one-dimensional condensates is considered from the perspective of energy and momentum conservation. By assuming the validity of Bogoliubov theory, the backreaction equations are used to identify the contributions to the system energy and momentum coming from quantum fluctuations and condensate corrections. The backreaction is solved for a condensate trapped in a ring configuration such that particle interactions are gradually switched on. It is shown that the energy in the condensate cannot be addressed without taking into account how the system entered the interacting regime, and even for homogeneous condensates the power transferred to the condensate by quantum fluctuations showcases an intricate nonmonotonic pattern.