Bose-Einstein supersolid phase for a novel type of momentum dependent interaction

TL;DR

This paper introduces a new class of momentum-dependent non-local interactions in bosons that stabilize a crystalline Bose-Einstein supersolid phase, analyzed through effective field theory and variational methods, revealing a phase diagram with specific conditions for supersolidity.

Contribution

It identifies a novel momentum-dependent interaction potential that favors a supersolid phase and provides a detailed phase diagram analysis using theoretical approaches.

Findings

The interaction potential has a negative minimum at finite momentum.

The supersolid wavevector is determined by the momentum minimum.

The wavelength of the supersolid exceeds the mean inter-boson distance.

Abstract

A novel class of non-local interactions between bosons is found to favor a crystalline Bose-Einstein condensation ground state. By using both low energy effective field theory and variational wavefunction method, we compare this state not only with the homogeneous superfluid, as has been done previously, but also with the normal (non-superfluid) crystalline phase and obtain the phase diagram. The key characters are: the interaction potential displays a negative minimum at finite momentum which determines the wavevector of this supersolid phase; and the wavelength corresponding to the momentum minimum needs to be greater than the mean inter-boson distance.