Transient Supersolid Properties in an Array of Dipolar Quantum Droplets

Fabian Böttcher,Jens Hertkorn,Tilman Pfau,Jan-Niklas Schmidt,Mingyang Guo,Tim Langen,Matthias Wenzel

doi:10.1103/physrevx.9.011051

Fabian Böttcher, Jens Hertkorn + Show 5 more

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https://doi.org/10.1103/physrevx.9.011051

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Abstract

We study theoretically and experimentally the emergence of supersolid properties in a dipolar Bose-Einstein condensate. The theory reveals a ground state phase diagram with three distinct regimes - a regular Bose-Einstein condensate, incoherent and coherent arrays of quantum droplets. In the latter the droplets are connected by a finite superfluid density, which leads - in addition to the periodic density modulation - to a robust phase coherence throughout the whole system. We further theoretically demonstrate that we are able to dynamically approach the ground state in our experiment and that its lifetime is only limited by three-body losses. Experimentally we probe and confirm the signatures of the phase diagram by observing the in-situ density modulation as well as the phase coherence using matter wave interference.

Highlights

We study theoretically and experimentally the emergence of supersolid properties in a dipolar BoseEinstein condensate
The concept of supersolidity has since been generalized to other superfluid systems and supersolid properties have been observed in ultracold atomic systems for spin-orbit-coupled Bose-Einstein condensates (BECs) [8] as well as BECs symmetrically coupled to two crossed optical cavities [9,10]
In Ref. [23] we pointed out that the ground state in strongly confined 2D geometries is made up of droplet arrays, but we experimentally observed that these arrays rapidly lose their relative coherence during their dynamical formation process

Summary

Introduction

We study theoretically and experimentally the emergence of supersolid properties in a dipolar BoseEinstein condensate. At the same time it was observed experimentally that phase-coherent droplets can exist for a narrow range of contact interaction strengths [25]. We observe a clear phase boundary where the density-modulated state becomes lower in energy than a regular BEC.

Results

Conclusion