Two-channel Bose-Hubbard model of atoms at a Feshbach resonance

摘要

Based on the analytic model of Feshbach resonances in harmonic traps described in Schneider et al. [Phys.nRev. A 83, 030701(R) (2011)] a Bose-Hubbard model is introduced that provides an accurate description of twonatoms in an optical lattice at a Feshbach resonance with only a small number of Bloch bands. The approachncircumvents the problem that the eigenenergies in the presence of a delta-like coupling do not converge to thencorrect energies, if an uncorrelated basis is used. The predictions of the Bose-Hubbard model are comparednto nonperturbative calculations for both the stationary states and the time-dependent wave function during annacceleration of the lattice potential. For this purpose, a square-well interaction potential is introduced, whichnallows for a realistic description of Feshbach resonances within nonperturbative single-channel calculations.