Mott transition in a two-leg Bose-Hubbard ladder under an artificial magnetic field

Abstract

We consider the Bose-Hubbard model on a two-leg ladder under an artificial magnetic field, and investigate the superfluid-to-Mott insulator transition in this setting. Recently, this system has been experimentally realized [M.Atala \textit{et al.}, Nature Physics \textbf{10}, 588--593 (2014)], albeit in a parameter regime that is far from the Mott transition boundary. Depending on the strength of the magnetic field, the single-particle spectrum has either a single ground state or two degenerate ground states. The transition between these two phases is reflected in the many-particle properties. We first investigate these phases through the Bogoliubov approximation in the superfluid regime and calculate the transition boundary for weak interactions. For stronger interactions the system is expected to form a Mott insulator. We calculate the Mott transition boundary as a function of the magnetic field and interleg coupling with mean-field theory, strong-coupling expansion and density matrix renormalization group (DMRG). Finally, using the DMRG, we investigate the particle-hole excitation gaps of this system at different filling factors and find peaks at simple fractions indicating the possibility of correlated phases.

10 pages, 9 figures

References in corpus (4)

• Composite Fermion Theory for Bosonic Atoms in Optical Lattices
• Theory of Bosons in two-leg ladders with large magnetic fields
• Phase Boundary of the Boson Mott Insulator in a Rotating Optical Lattice
• Signatures of the superfluid to Mott insulator transition in cold bosonic atoms in a one dimensional optical lattice

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• Neural-network quantum states for a two-leg Bose-Hubbard ladder under magnetic flux
• Flux enhanced localization and reentrant delocalization in the quench dynamics of two interacting bosons on a Bose-Hubbard ladder
• Flux induced re-entrant dynamics in the quantum walk of interacting bosons
• Quantum phases of constrained bosons on a two-leg Bose-Hubbard ladder
• Ground-state phase diagram of two-component interacting bosons on a two-leg ladder
• Mott-insulating phases of the Bose-Hubbard model on quasi-1D ladder lattices
• Dynamics of interacting bosons in a two-leg ring ladder with artificial magnetic flux and ac-driven modulations