FisMat2017 - Submission - View

Abstract's title: Nonlocal Parity Order in the Two-Dimensional Mott Insulator
Submitting author: Serena Fazzini
Affiliation: Politecnico di Torino
Affiliation Address: Corso Duca degli Abruzzi, 24 - 10129 Torino
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations:

The Mott insulator is characterized by having small deviations around the (integer) average particle density n, with pairs
with n-1 and n+1 particles forming bound states. In one dimension the effect is captured by a non-zero value of a non-local ``string'' parity operator, which by contrast vanishes in the superfluid phase, where density fluctuations are large. Here,
we investigate the interaction induced transition from the superfluid to the Mott insulator, in the paradigmatic Bose Hubbard model
at n=1. By means of quantum Monte Carlo simulations and finite size scaling analysis, we explore the behavior of  brane parity operators from the one-dimensional to the two-dimensional limit. We confirm the conjecture that, adopting a standard definition, their average value decays to zero in two dimensions also in the insulating phase, evaluating the scaling factor of the perimeter law [S.P. Rath {\it et al.}, Ann. Phys. (N.Y.) {\bf 334}, 256 (2013)]. Upon introducing a further phase in the brane parity, we show that its expectation value is instead finite in the insulator, while vanishing at the transition to the superfluid phase. These quantities are directly accessible to experimental measures,  providing an insightful signature of the Mott insulator.