arXiv:2003.09678 · Physical Review A

Comment on “Berezinskii-Kosterlitz-Thouless transition in two-dimensional dipolar stripes”

Fabio Cinti, Massimo Boninsegni

Published Oct 19, 2020• 3 citations

Abstract

In a recent article [R. Bombin, F. Mazzanti, and J. Boronat, Phys. Rev. A 100, 063614 (2019)], it is contended that a two-dimensional system of dipolar bosons, with dipole moments aligned at particular angles with respect to the direction perpendicular to the plane of motion, featuring a ``striped'' crystalline ground state, in turn undergoes a Berezinskii-Kosterlitz-Thouless superfluid transition at low temperature, making it a two-dimensional supersolid. We show here that the results provided therein, obtained by means of quantum Monte Carlo simulations, do not actually support such a conclusion. Rather, they are consistent with that expounded in our work [J. Low Temp. Phys. 196, 413 (2019)], namely that the striped ground state is insulating (i.e., nonsuperfluid in the conventional sense), essentially behaving like a system of quasi-one-dimensional, parallel independent chains. We attribute the incorrectness of the conclusion reached by Bombin, Mazzanti, and Boronat to the very small sizes of their simulated system, which do not allow for a reliable extrapolation to the thermodynamic limit.

DOI: 10.1103/physreva.102.047301

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This is a Reply to the Comment from F. Cinti and M. Boninsegni on our recent work on the Berezinskii-Kosterlitz-Thouless (BKT) phase transition in a two-dimensional dipolar system [Bomb\'{\i}n, Mazzanti, and Boronat, Phys. Rev. A 100, 063614 (2019)]. The main criticism about our work expressed in that Comment is that we did not explicitly report the two spatial contributions to the total superfluid fraction. Here we analyze our results for a point of the phase diagram corresponding to the stripe phase, close to the gas-to-stripe transition line, and for a temperature below the BKT critical temperature. The scaling with the system size of the contribution to the superfluid fraction, coming from the direction in which spatial order appears, shows that it remains finite in the thermodynamic limit, as we already stated in our original work. This allow us to state that the stripe phase is superfluid at low temperatures. Furthermore, we offer some comments that help to understand where the differences between the results of Cinti and Boninsegni and ours come from.

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