Self-bound supersolid stripe phase in binary Bose-Einstein condensates

Abstract

Supersolidity-a coexistence of superfluidity and crystalline or amorphous density variations-has been vividly debated ever since its conjecture. While the initial focus was on helium-4, recent experiments uncovered supersolidity in ultracold dipolar quantum gases. Here we propose a self-bound supersolid phase in a binary mixture of Bose gases with short-range interactions, making use of the nontrivial properties of spin-orbit coupling. We find that a first-order phase transition from a self-bound supersolid stripe phase to a zero-minimum droplet state of the Bose gas occurs as a function of the Rabi coupling strength. These phases are characterized using the momentum distribution, the transverse spin polarization, and the superfluid fraction. The critical point of the transition is estimated in an analytical framework. The predicted density-modulated supersolid stripe and zero-minimum droplet phase should be experimentally observable in a binary mixture of 39 K with spin-orbit coupling.

Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures

“…As we concluded in the main text, for a thermal distribution at equilibrium and by working in the momentum space, one has [34] ρ mn (r − r ′ ) = dk (2π) 3 e ik. (r−r ′ ) ρ mn (k), (17) where ρ mn (k) is the Fourier transform of ρ mn (r − r ′ ). After some algebra, expression (2) turns out to be given as:…”

“…The binary Bose-Einstein condensates (BECs) with weak attractive inter-and repulsive intraspecies interactions support also the creation of ultradilute liquid-like droplets in two-dimensional (2D) configuration [13]. In the last few years, 2D quantum droplets have been studied from a variety of aspects including: effects of the spin-orbit coupling [14], formation and stability of quantum Rabi-coupled droplets [15], superfluidity and vortices [16], supersolid stripe phase [17], dynamical excitations [18], bulk properties and quantum phases [19,20].…”

Many-body and temperature effects in two-dimensional quantum droplets in Bose–Bose mixtures

“…The binary Bose–Einstein condensates (BECs) with weak attractive inter- and repulsive intraspecies interactions support also the creation of ultradilute liquid-like droplets in two-dimensional (2D) configuration 13 . In the last few years, 2D quantum droplets have been studied from a variety of aspects including: effects of the spin-orbit coupling 14 , formation and stability of quantum Rabi-coupled droplets 15 , superfluidity and vortices 16 , supersolid stripe phase 17 , dynamical excitations 18 , bulk properties and quantum phases 19 , 20 .…”

Quantum self-bound droplets in Bose-Bose mixtures: Effects of higher-order quantum and thermal fluctuations

“…Most recently, the self-bound supersolid stripe phase in binary BEC has been predicted in Ref. [14].…”