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arXiv · 1504.06159

Population-imbalance instability in a Bose-Hubbard ladder in the presence of a magnetic flux

Shun Uchino·Akiyuki Tokuno
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Abstract

We consider a two-leg Bose-Hubbard ladder in the presence of a magnetic flux. We make use of Gross-Pitaevskii, Bogoliubov, bosonization, and renormalization group approaches to reveal a structure of ground-state phase diagrams in a weak-coupling regime relevant to cold atom experiments. It is found that except for a certain flux $ϕ=π$, the system shows different properties as changing hoppings, which also leads to a quantum phase transition similar to the ferromagnetic XXZ model. This implies that population-imbalance instability occurs for certain parameter regimes. On the other hand, for $ϕ=π$, it is shown that an umklapp process caused by commensurability of a magnetic flux stabilizes a superfluid with chirality and the system does not experience such a phase transition.

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Shun Uchino, Akiyuki Tokuno. 2015-07-23. Population-imbalance instability in a Bose-Hubbard ladder in the presence of a magnetic flux. https://doi.org/10.1103/physreva.92.013625

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