"Competing interactions in dipolar erbium atoms"
Who: Gabriele Natale, University of Innsbruck, Austria
Place: Donostia International Physics Center
Date: Friday, 10 February 2023, 12:30
Ultracold magnetic atoms exhibit short-range contact interactions together with long-range dipole-dipole interactions. The competition between these two interactions gives rise to various quantum phases , where the usually dominant mean-field interactions are small and the system is governed by quantum fluctuations .
In this talk, I will first report on the study of a supersolid state and its excitation spectrum . In such a state, two symmetries are spontaneously broken: the gauge symmetry, associated with the phase coherence of a superfluid, and the translational invariance, signalizing crystalline order. As a result, two distinct branches appear in the excitation spectrum, one for each broken symmetry. In the second part of the talk, we add a one-dimensional optical lattice to the system and create a platform, in which quantum fluctuations are still unexplored and a variety of new phases may be observable. We employ Bloch oscillations as an interferometric tool to assess the role that quantum fluctuations play in an array of quasi-two- dimensional Bose-Einstein condensates . We observe a transition to a state localized into a single lattice site purely driven by interactions. Finally, we uncover the parameter regimes where both droplet and soliton states can be achieved.
 L. Chomaz, I. Ferrier-Barbut, F. Ferlaino, B. Laburthe- Tolra, B. L. Lev, and T.Pfau, Dipolar physics: A review of experiments with magnetic quantum gases. ArXiv: 2201.02672 (2022)
 A. R. P. Lima and A. Pelster, Beyond mean-field low- lying excitations of dipolar Bose gases, Phys.Rev. A 86, 063609 (2012)
 G. Natale, R.M.W. van Bijnen, A. Patscheider, D. Petter, M.J. Mark, L. Chomaz, and F. Ferlaino, Excitation Spectrum of a Trapped Dipolar Supersolid and Its Experimental Evidence, Phys. Rev. Lett. 123, 050402 (2019)
 G. Natale, T. Bland, S. Gschwendtner, L. Lafforgue, D. S. Grun, A. Patscheider, M. J. Mark and F. Ferlaino, Bloch oscillations and matter-wave localization of a dipolar quantum gas in a one dimensional lattice, Comm. Phys. 5, 227 (2022)
Host: Ricardo Diez Muino
Note: This lecture is part of the joint session with talk by Claudia Politi scheduled at 12:00 p.m.