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

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

Andrzej Syrwid, Arkadiusz Kosior, and Krzysztof Sacha

Phys. Rev. Lett. 124, 178901 – Published 29 April 2020

Abstract

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.

Received 2 March 2020
Accepted 3 April 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.178901

Physics Subject Headings (PhySH)

Bose-Einstein condensates Cold atoms & matter waves Synthetic gauge fields

Atomic, Molecular & Optical

Authors & Affiliations

Andrzej Syrwid ^1,2, Arkadiusz Kosior ^1,3, and Krzysztof Sacha ¹

¹Instytut Fizyki Teoretycznej, Uniwersytet Jagielloński, ulica Profesora Stanisława Łojasiewicza 11, PL-30-348 Kraków, Poland
²Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University, Collège de France; 4 Place Jussieu, 75005 Paris, France
³Max-Planck-Institut für Physik Komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany