Boson Hubbard model with weakly coupled Fermions

Lutchyn, R. M.; Tewari, S.; Sarma, S. Das

Boson Hubbard model with weakly coupled Fermions

Authors

Lutchyn, R. M.

Tewari, S.

Sarma, S. Das

Description

Using an imaginary-time path integral approach, we develop the perturbation theory suited to the boson Hubbard model, and apply it to calculate the effects of a dilute gas of spin-polarized fermions weakly interacting with the bosons. The full theory captures both the static and the dynamic effects of the fermions on the generic superfluid-insulator phase diagram. We find that, in a homogenous system described by a single-band boson Hubbard Hamiltonian, the intrinsic perturbative effect of the fermions is to generically suppress the insulating lobes and to enhance the superfluid phase.
4 pages, 1 figure; final version as published in PRB