Observation of a Dipolar Quantum Gas with Metastable Supersolid Properties

Abstract

The competition of dipole-dipole and contact interactions leads to exciting new physics in dipolar gases, well-illustrated by the recent observation of quantum droplets and rotons in dipolar condensates. We show that the combination of the roton instability and quantum stabilization leads under proper conditions to a novel regime that presents supersolid properties, due to the coexistence of stripe modulation and phase coherence. In a combined experimental and theoretical analysis, we determine the parameter regime for the formation of coherent stripes, whose lifetime of a few tens of milliseconds is limited by the eventual destruction of the stripe pattern due to three-body losses. Our results open intriguing prospects for the development of long-lived dipolar supersolids. arXiv:1811.02613v2 [cond-mat.quant-gas]

Berezinskii-Kosterlitz-Thouless transition in two-dimensional dipolar stripes

“…For temperatures lower than T c , the superfluid fraction shows a plateau around a value which is in agreement with the zero-temperature result derived previously using the diffusion Monte Carlo method [12], ns n nr 2 0 =256 α=0.6 = 0.54 (5).…”

“…Still in the context of ultracold gases, dipolar systems have been postulated as good candidates to the supersolid state. In fact, supersolid signatures have been observed by several groups [5][6][7], following previous theoretical work [8]. Recently, the gapless Goldstone excitation has also been measured for the same system [9][10][11].…”

Two-dimensional quantum droplets in dipolar Bose gases

“…Our simulations are carried out for 162 Dy atoms, with typical atom number N=10 4 and a=141a 0 [33] (a 0 being the Bohr radius) which can be controlled via a magnetic Feshbach. Dy atoms in their ground state have a dipolar length r * =130a 0 [23,34]. In this configuration a roton mode is expected to appear.…”

Dynamical formation of quantum droplets in a K39 mixture

“…Although forming in dilute atomic gases, they display properties which are unique in that context but common to different systems such as classical liquids, helium nanodroplets or atomic nuclei. After their existence in attractive bosonic mixtures was theoretically predicted in [1], they have been experimentally observed in dipolar condensates [5][6][7][8], homonuclear mixtures of 39 K [9,10] and recently in a heteronuclear mixture of 41 K and 87 Rb [11].…”