Patterned Supersolids in Dipolar Bose Systems

Abstract

We study by means of first principle Quantum Monte Carlo simulations the ground state phase diagram of a system of dipolar bosons with aligned dipole moments, and with the inclusion of a two-body repulsive potential of varying range. The system is shown to display a supersolid phase in a relatively broad region of the phase diagram, featuring different crystalline patterns depending on the density and on the range of the repulsive part of the interaction (scattering length). The supersolid phase is sandwiched between a classical crystal of parallel filaments and a homogeneous superfluid phase. We show that a "roton" minimum appears in the elementary excitation spectrum of the superfluid as the system approaches crystallization. The predictions of this study are in quantitative agreement with recent experimental results.

Cluster stability driven by quantum fluctuations

“…To conclude, extending the present study, future work may address how similar complex structures can control quantum-mechanical exchanges, considering other two or multi-lengthscale soft-core potentials, possibly applicable in an experimental contest as, for instance, ultra-cold dipolar atoms [43][44][45][46][47][48][49] or supporting the understanding of other engaging systems such as quantum quasicrystals [50,51].…”

Vortex properties in the extended supersolid phase of dipolar Bose-Einstein condensates

“…Such dispersion relation has some similarities with that of superfluid 4 He [1,4]. When the ratio of the dipolar to the short-range interaction increases beyond a critical value, a spontaneous density modulation occurs which is driven by the softening of the roton mode at finite momentum k R , and the resulting system has supersolid character [12,[14][15][16][17][18]. The density modulation, with wavelength ∼2π/k R , results in an ordered array of "droplets," made of many atoms each, elongated in the direction of the polarization axis.…”

Saga of Superfluid Solids

“…The coherent droplets are connected by a background condensate, which leads to a phase coherence throughout the whole system. Quantum Monte Carlo simulations for dipolar systems with aligned dipolar moments have shown [198,199] that at low temperature there can develop triangular periodic structures composed of filaments or droplets containing many coherent atoms possessing superfluid properties. Between different droplets or across different filaments there can arise quantum-mechanical particle exchanges allowing for the global phase coherence and a superfluid response.…”