SAMOP 2021 – scientific programme
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A: Fachverband Atomphysik
A 16: Ultra-cold atoms, ions, and BEC (joint session A/Q)
A 16.15: Poster
Wednesday, September 22, 2021, 16:30–18:30, P
Density Fluctuations across the Superfluid-Supersolid Phase Transition in a Dipolar Quantum Gas — •Jan-Niklas Schmidt1, Jens Hertkorn1, Mingyang Guo1, Kevin Ng1, Sean Graham1, Paul Uerlings1, Tim Langen1, Martin Zwierlein2, and Tilman Pfau1 — 15. Physikalisches Institut and Center for Integrated Quantum Science and Technology IQST, Universität Stuttgart — 2MIT-Harvard center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
Supersolidity is a counter-intuitive state of matter that simultaneously shows superfluid flow and crystalline order. Dipolar quantum gases confined in elongated trapping geometries feature an interaction induced modulational instability driven by the softening of a roton excitation that eventually get stabilized by quantum fluctuations. By directly measuring density fluctuation in situ we extract the static structure factor across the transition, identify the roton modes as the dominant cause of the crystallization, and simultaneously observe BEC and crystal phonons on the supersolid side of the transition as a hallmark of supersolidity. An advanced study in circularly symmetric trapping geometries reveals the role of angular roton excitations in the crystallization process to two-dimensional droplet arrays. This understanding forms an important step toward the realization of a two-dimensional dipolar supersolid marking just the starting point to a rich phase diagram of structured patterns including novel exotic phases such as supersolid honeycomb and amorphous labyrinthine phases.