Spin liquid and Deconfined Criticality in a Kagome Lattice Bose-Hubbard Model

Note: Note: 1:30 PM, SCI328
Speaker: Roger Melko, University of Waterloo, Canada

When: November 18, 2011 (Fri), 01:30PM to 02:30PM (add to my calendar)
Location: SCI 328
Hosted by: Anders Sandvik

This event is part of the Condensed Matter Theory Seminar Series.

Abstract:
We present large-scale quantum Monte Carlo simulations on a sign-problem free
Bose-Hubbard model on the kagome lattice. This model supports a quantum Z2 spin
liquid phase with fractional excitations and topological order, which can be
characterized definitively through calculation of the topological entanglement
entropy.  I will outline how the entanglement entropy can be measured in general
using a direct implementation of the familiar "replica trick", which allows for
the study of entanglement scaling in a variety of other models amenable to study by QMC. Finally, I will examine the kagome model's superfluid/spin-liquid
transition, which is an example of an exotic deconfined quantum critical point
called XY*, mediated by the fractional charges.  This fact is demonstrated in
several universal quantities that we measure, and may also be reflected the
scaling of entanglement entropy at the critical point.