Exploring supersolidity with spin-orbit coupled BEC | Leticia Tarruell (ICFO & ICREA)

This Video was recorded on 9 April 2024 as part of the MCQST Colloquium which takes place at ‪@maxplanckquantum‬

Exploring supersolidity with spin-orbit coupled Bose-Einstein condensates | Leticia Tarruell (ICFO & ICREA)

Abstract:
Supersolidity is a counter-intuitive phase of matter that spontaneously breaks both gauge and translation symmetry, and combines the frictionless flow of a superfluid and the crystalline structure of a solid. Until now supersolids have only been realized in Bose-Einstein condensates, exploiting three different ingredients: dipolar interactions, cavity-mediated interactions, and spin-orbit coupling. The properties of dipolar and cavity supersolids have been explored in detail, showing common features but also important differences concerning their excitation spectra. In contrast, all spin-orbit coupled supersolids realized to date were very fragile, and could only be probed indirectly. This led to contradictory opinions concerning the properties of their modulated density profile, also known as the stripe pattern, and of their collective excitations. In my talk, I will present recent experiments where we leverage the tunable interaction properties of potassium atoms to realize robust supersolids in a spin-orbit coupled Bose-Einstein condensate, and to observe in situ for the first time their modulated density profiles. We demonstrate that, unlike in cavity supersolids, the supersolid stripe spacing is not fixed: it varies with the spin-orbit coupling strength and hosts a stripe compression mode. Moreover, we measure the softening of the stripe compression mode frequency with increasing spin-orbit coupling strength, revealing in this way the supersolid phase transition. Our experiments establish spin-orbit coupled Bose-Einstein condensates as an attractive alternative platform to investigate supersolidity, and provide an excellent starting point to explore its interplay with quantum fluctuations and external lattice potentials.

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The MCQST Colloquium Series features interdisciplinary talks given by visiting international speakers. The monthly colloquium covers topics spanning all MCQST research units and is broadcasted live via Zoom for audiences worldwide. The main goal of the series is to create the framework for idea exchange, to strengthen links with QST leading groups worldwide, as well as to act as an integral part of the local educational environment.
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