A quantum liquid with deconfined fractional excitations in three dimensions

Note: 10:00 AM
Speaker: Nic Shannon, University of Bristol

When: March 24, 2010 (Wed), 10:00AM to 11:00AM (add to my calendar)

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

Abstract:
Excitations which carry ``fractional’‘ quantum numbers are known to exist in one dimension
in polyacetylene, and in two dimensions, in the fractional quantum Hall effect. Fractional
excitations have also been invoked to explain the breakdown of the conventional theory of
metals in a wide range of three-dimensional materials. However the existence of fractional
excitations in three dimensions remains highly controversial.

Here we report direct numerical evidence for the existence of an extended quantum liquid phase supporting fractional excitations in a concrete, three-dimensional microscopic
model —- the quantum dimer model on a diamond lattice [1].

We demonstrate explicitly that the energy cost of separating fractional monomer
excitations vanishes in this liquid phase, and that its energy spectrum matches
that of the Coulomb phase in (3+1) dimensional quantum electrodynamics [2,3].

[1] O. Sikora et al., Phys. Rev. Lett 103, 247001 (2009)
[2] R. Moessner and S.L. Sondhi, Phys. Rev. B 68, 184512 (2003).
[3] D.L. Bergman et al., Phys. Rev. B 73, 134402 (2006).