Comment on "Coherent Ratchets in Driven Bose-Einstein Condensates"
arXiv:0912.3667 · doi:10.1103/PhysRevLett.104.228901
Abstract
C. E. Creffield and F. Sols (Phys. Rev. Lett. 103, 200601 (2009)) recently reported finite, directed time-averaged ratchet current, for a noninteracting quantum particle in a periodic potential even when time-reversal symmetry holds. As we explain in this Comment, this result is incorrect, that is, time-reversal symmetry implies a vanishing current.
revised version