Since the realisation by Bose and Einstein in 1924 that the quantum ground state of a system is special in many ways, researchers have worked towards creating a quantum system with many particles occupying that ground state, now called a Bose-Einstein Condensate (BEC), with the first successful demonstration in 1995.
Here, we argue that BECs can be formed in non-ground states as we recently demonstrated and that the laboratory ground state does not have zero kinetic energy, as asserted by Einstein in 1925. We show that some naïve transformations in the literature have mistakenly supported the zero-kinetic energy ground state argument.
With this paper, we clarify the necessary conditions for a Bose condensate and pave the way for future experiments with non-ground state condensates.
The paper can be found here:
“A Bose-Einstein condensate is a Bose condensate in the laboratory ground state” published online and to appear in the October print issue with Proceedings of the Royal Society A. 477, p.20210465 doi: 10.1098/rspa.2021.0465