Thomas Bland

Investigating vortices in dipolar quantum gases

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Following our recent experimental observation of vortices in Bose-Einstein condensates comprised of atoms with inherent long-range dipole-dipole interactions [Nat. Phys. 18, 1453-1458 (2022)], we thoroughly investigate vortex properties in the three-dimensional dominantly dipolar regime, where beyond-mean-field effects are crucial for stability, and investigate the interplay between trap geometry and magnetic field tilt angle. Last year, Jean Dalibard was awarded with the most prestigious French prize for physicists, the CNRS Gold medal, and this work is our contribution to a Special Issue honouring his many contributions to the field of ultracold atoms, and in particular his work on quantum vortices. See the full collection here: CNRS Gold Medal Jean Dalibard (academie-sciences.fr).

See the pre-print here: arXiv:2303.13263

Austrian Quantum Simulator Infrastructure granted

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In the Framework of the Quantum Austria Initiative a joint project from the University of Innsbruck and the TU Wien was awarded and starts at the beginning of 2023. The “Austrian Quantum Simulator Infrastructure” project with a total funding of about 3 Million Euros will greatly enhance the already existing quantum simulators in several labs in Innsbruck and Vienna and also help in the building up of new simulators. Quantum simulators are a very powerful tool to study complex quantum systems by mimicking their behaviour with a quantum system which is fully controllable. The project consortium combines a great variety of physical systems which are used as simulators, including solid-state systems, ultracold atoms and trapped ions. Our group is participating with our long-range interacting atoms inside an optical lattice and our Rydberg tweezer array experiment.

Anti-dipolar supersolids are anti-boring!

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By rapidly rotating the dipole moment in an ultracold Bose gas it is possible to tune the dipole-dipole interaction. Rotating dipoles around the origin of the x-y plane, for example, gives a time averaged interaction that is equivalent to anti-dipoles oriented along the z axis! This means that the effective interaction is opposite: head-to-tail anti-dipoles repel, and side-by-side anti-dipoles attract! In an infinite tube of anti-dipoles, this means that the possible supersolid states have cylindrical symmetry around the x-y axis, which we utilize to facilitate analytic predictions, and faster numerical simulations, of two-component antidipolar supersolids!

See the pre-print here: arXiv:2301.08007

Review of recent experiments with dipolar gases

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The last 15 years has seen tremendous experimental progress for the manipulation and control of ultracold atoms with sizeable dipole-dipole interactions. In this review, together with other group leaders who first condensed dysprosium and chromium, we review the discoveries made so far, and lay out the future perspectives for this exciting field!

The paper can be found here: Dipolar physics: a review of experiments with magnetic quantum gases – IOPscience

Double the supersolid, double the fun?

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Here in Innsbruck, and in Stuttgart and Pisa, clouds of ultracold dipolar atoms have recently been observed in the long-sought after supersolid state, in which there exists global phase coherence and crystalline density structure in the superfluid. Two-component dipolar gases are also now experimentally producible, with our erbium and dysprosium mixtures, however the fate of the supersolid state remains largely unknown.
Together with researchers from Hanover, we predict the existence of a binary supersolid state in which the two components form a series of alternating domains, producing an immiscible double supersolid. Remarkably, we find that a dipolar component can even induce supersolidity in a nondipolar component. In stark contrast to single-component supersolids, the number of crystal sites is not strictly limited by the condensate populations, and the density is hence substantially lower. Our results are applicable to a wide range of dipole moment combinations, marking an important step towards long-lived bulk-supersolidity.
See the pre-print here: arXiv:2203.11119, and the now published paper here: PhysRevA.106.053322

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