414 research outputs found
Thermal melting of density waves on the square lattice
We present the theory of the effect of thermal fluctuations on commensurate
"p x p" density wave ordering on the square lattice (p >= 3, integer). For the
case in which this order is lost by a second order transition, we argue that
the adjacent state is generically an incommensurate striped state, with
commensurate p-periodic long range order along one direction, and
incommensurate quasi-long-range order along the orthogonal direction. We also
present the routes by which the fully disordered high temperature state can be
reached. For p=4, and at special commensurate densities, the "4 x 4"
commensurate state can melt directly into the disordered state via a self-dual
critical point with non-universal exponents.Comment: 12 pages, 5 figure
A Path Integral Ground State Monte Carlo Algorithm for Entanglement of Lattice Bosons
A ground state path integral quantum Monte Carlo algorithm is introduced that
allows for the study of entanglement in lattice bosons at zero temperature. The
R\'enyi entanglement entropy between spatial subregions is explored across the
phase diagram of the one dimensional Bose-Hubbard model for systems consisting
of up to sites at unit-filling without any restrictions on site
occupancy, far beyond the reach of exact diagonalization. The favorable scaling
of the algorithm is demonstrated through a further measurement of the R\'enyi
entanglement entropy at the two dimensional superfluid-insulator critical point
for large system sizes, confirming the existence of the expected entanglement
boundary law in the ground state. The R\'enyi estimator is extended to measure
the symmetry resolved entanglement that is operationally accessible as a
resource for experimentally relevant lattice gases with fixed total particle
number.Comment: ~50 pages, 21 figures. Updated refs, figures, and discussion. For
associated data and code repository see:
https://github.com/DelMaestroGroup/papers-code-pigsfl
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