title: Interacting Hofstadter spectrum of atoms in an artificial gauge field.
abstract: Motivated by experimental advances in the synthesis of gauge potentials for ultracold atoms, we consider the superfluid phase of interacting bosons on a square lattice in the presence of a magnetic field. We show that superfluid order implies spatial symmetry breaking, and predict clear signatures of many-body effects in time-of-flight measurements. By developing a Bogoliubov expansion based on the exact Hofstadter spectrum, we find the dispersion of the quasiparticle modes within the superfluid phase, and describe the consequences for Bragg spectroscopy measurements. The theory also provides an estimate of the critical interaction strength at the transition to the Mott insulator phase.
authors.affiliation: Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Powell
authors.forename: Ryan
authors.initials: R
authors.lastname: Barnett
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Sensarma
authors.forename: Sankar
authors.initials: S
authors.lastname: Das Sarma