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Chiral magnetism and spontaneous spin Hall effect of interacting Bose superfluids

TitleChiral magnetism and spontaneous spin Hall effect of interacting Bose superfluids
Publication TypeJournal Article
Year of Publication2014
AuthorsX. Li, S. S. Natu, A. Paramekanti, and S. Das Sarma
JournalNature Communications
Date Published10/2014
Keywordschiral magnetism, Spin-orbit coupling

Recent experiments on ultracold atoms in optical lattices have synthesized a variety of tunable bands with degenerate double-well structures in momentum space. Such degeneracies in the single-particle spectrum strongly enhance quantum fluctuations, and often lead to exotic many-body ground states. Here we consider weakly interacting spinor Bose gases in such bands, and discover a universal quantum ‘order by disorder’ phenomenon which selects a novel superfluid with chiral spin order displaying remarkable properties such as spontaneous spin Hall effect and momentum space antiferromagnetism. For bosons in the excited Dirac band of a hexagonal lattice, such a state supports staggered spin loop currents in real space. We show that Bloch oscillations provide a powerful dynamical route to quantum state preparation of such a chiral spin superfluid. Our predictions can be readily tested in spin-resolved time-of-flight experiments.


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