Self-bound droplets in quasi-two-dimensional dipolar condensates

Abstract

We study the ground-state properties of self-bound dipolar droplets in quasi-two-dimensional geometry by using the Gaussian state theory. We show that there exist two quantum phases corresponding to the macroscopic squeezed vacuum and squeezed coherent states. We further show that the radial size versus atom number curve exhibits a double-dip structure, as a result of the multiple quantum phases. In particular, we find that the critical atom number for the self-bound droplets is determined by the quantum phases, which allows us to distinguish the quantum state and validates the Gaussian state theory.

Macroscopic squeezing in quasi-one-dimensional two-component Bose gases

“…More importantly, GST gives rise to the gapless excitation spectrum of condensates [36,42,43], which remedies the flaw of the Hartree-Fock-Bogoliubov theory. As to the stabilization mechanism of the dipolar and binary droplets, our studies showed that they were stablized by the three-body repulsion, instead of the quantum fluctuation [37][38][39]. In particular, we found two new macroscopic squeezed states in droplets, i.e.…”

“…In a series of works [36][37][38][39][40], we studied the ground-state properties and the dynamics of the atomic condensates using the self-consistent Gaussian-state theory (GST) that takes account of the fluctuation at the Hartree-Fock-Bogoliubov level [41]. More importantly, GST gives rise to the gapless excitation spectrum of condensates [36,42,43], which remedies the flaw of the Hartree-Fock-Bogoliubov theory.…”

“…Physically, these macroscopic squeezed states distinguish themselves from the CS state by having a large second-order correlation and an asymmetric atom-number distribution [36,37], which allows the potential experimental detection of the new quantum phases. In addition, for quasi-two-dimensional (quasi-2D) droplets, we showed that the multiple quantum phases can be identified from the radial size versus atom number curve [38,39]. As to the dynamics of the atomic condensates, we studied the collapse dynamics of a single-component condensate with attractive interaction [40].…”