Paper detail

Comment on "Quantum Time Crystals and Interacting Gauge Theories in Atomic Bose-Einstein Condensates"

In a recent letter [Phys. Rev. Lett. 123, 250402], Öhberg and Wright describe a Bose-Einstein condensate trapped on a ring in the presence of the density-dependent gauge potential. It is claimed that the ground state of the system corresponds to a rotating chiral bright soliton and consequently it forms a genuine time crystal which minimizes its energy by performing periodic motion. We show that the energy of the chiral soliton in the laboratory frame is not correctly calculated in the letter. The correct energy becomes minimal if the soliton does not move.