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 suppress the Mott insulating lobes and enhance the superfluid phase.
*Work supported by ARO-DARPA
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Authors
Sumanta Tewari
Department of Physics, Clemson University, Clemson, SC
Department of Physics and Astronomy, Clemson University
Roman Lutchyn
Condensed Matter Theory Center (CMTC) and Joint Quantum Institute (JQI), University of Maryland, College Park, MD
Condensed Matter Theory Center (CMTC) and Joint Quantum Institute (JQI), Department of Physics, University of Maryland, College Park, MD
University of Maryland
Sankar Das Sarma
Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, MD
University of Maryland
University of Maryland, College Park
Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park MD 20742
