Lecturer: Dr. Snir Gazit
Affiliation: Condensed-Matter Theory Center,
University of California Berkeley
Abstract:
Lattice gauge theories are ubiquitous in
physics, describing a wide range of
phenomena from quark confinement to
quantum materials. At finite fermion density,
gauge theories are notoriously hard to
analyze due to the fermion sign problem.
Here, we investigate the Ising gauge theory in
2+1 dimensions, a problem of great interest in
condensed matter, and show that it is free of
the sign problem at arbitrary fermion density.
At generic filling, we find that gauge
fluctuations mediate pairing leading to a
transition between a deconfined BCS state to
a confined BEC. At half-filling, a $\pi$-flux
phase is generated spontaneously with
emergent Dirac fermions. The deconfined
Dirac phase, with a vanishing Fermi surface
volume, is a non-trivial example of violation of
Luttinger's theorem due to fractionalization.
At strong coupling, we find a single
continuous transition between the
deconfined Dirac phase and the confined BEC,
in contrast to the expected split transition.