Tunneling-induced restoration of the degeneracy and the time-reversal symmetry breaking in optical lattices.

Phys Rev Lett

Institute of Physics of the Polish Academy of Sciences, Aleja Lotników 32/46, PL-02-668 Warsaw, Poland and ICFO, The Institute of Photonic Sciences, Avenue Carl Friedrich Gauss, No. 3, E-08860 Castelldefels (Barcelona), Spain and Center for Theoretical Physics of the Polish Academy of Sciences, Aleja Lotników 32/46, PL-02-668 Warsaw, Poland.

Published: November 2013

We study the ground-state properties of bosons loaded into the p band of a one-dimensional optical lattice. We show that the phase diagram of the system is substantially affected by the anharmonicity of the lattice potential. In particular, for a certain range of tunneling strength, the full many-body ground state of the system becomes degenerate. In this region, an additional symmetry of the system, namely, the parity of the occupation number of the chosen orbital, is spontaneously broken. The state with a nonvanishing staggered angular momentum, which breaks the time-reversal symmetry, becomes the true ground state of the system.

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http://dx.doi.org/10.1103/PhysRevLett.111.215302DOI Listing

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