Defect-induced supersolidity with soft-core bosons

TL;DR

This paper demonstrates a theoretical model where two-dimensional soft-core bosons exhibit a supersolid phase at zero temperature, showing spontaneous vacancies and superfluidity within a crystal, confirming a long-standing hypothesis.

Contribution

It provides the first clear example of defect-induced supersolidity in continuous space, aligning with the Andreev-Lifshitz-Chester scenario.

Findings

Spontaneous zero-point vacancies appear at low densities.

Superfluid flow coexists with crystalline order.

First unambiguous demonstration of defect-induced supersolidity.

Abstract

More than 40 years ago, Andreev, Lifshitz, and Chester suggested the possible existence of a peculiar solid phase of matter, the microscopic constituents of which can flow superfluidly without resistance due to the formation of zero-point defects in the ground state of self-assembled crystals. Yet, a physical system where this mechanism is unambiguously established remains to be found, both experimentally and theoretically. Here we investigate the zero-temperature phase diagram of two-dimensional bosons with finite-range soft-core interactions. For low particle densities, the system is show to feature a solid phase in which zero-point vacancies emerge spontaneously and give rice to superfluid flow of particles through the crystal. This provides the first example of defects-induced, continuous-space supersolidity consistent with the Andreev-Lifshitz-Chester scenario.