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Updated: Dec 21, 2025

Gradient Echo Quantum Memory in Warm Atomic Vapor
Published on: November 11, 2013
Comment on "Quantum Time Crystals and Interacting Gauge Theories in Atomic Bose-Einstein Condensates"
Andrzej Syrwid1,2, Arkadiusz Kosior1,3, Krzysztof Sacha1
1Instytut Fizyki Teoretycznej, Uniwersytet Jagielloński, ulica Profesora Stanisława Łojasiewicza 11, PL-30-348 Kraków, Poland.
Abstract:
In a recent Letter [Phys. Rev. Lett. 123, 250402PRLTAO0031-900710.1103/PhysRevLett.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.
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