A Bose–Einstein condensate is a Bose condensate in the laboratory ground state

Abstract

Bose–Einstein condensates of weakly interacting, ultra-cold atoms have become a workhorse for exploring quantum effects on atomic motion, but does this condensate need to be in the ground state of the system? Researchers often perform transformations so that their Hamiltonians are easier to analyse. However, changing Hamiltonians can require an energy shift. We show that transforming into a rotating or oscillating frame of reference of a Bose condensate does not then satisfy Einstein’s requirement that a condensate exists in the zero kinetic energy state. We show that Bose condensation can occur above the ground state and at room temperature, referring to recent literature.