Ultracold magnetic atoms exhibit short-range contact interactions together with longrange
dipole-dipole interactions. The competition between these two interactions
gives rise to various quantum phases [1], where the usually dominant mean-field
interactions are small and the system is governed by quantum fluctuations [2].
In this talk, I will first report on the study of a supersolid state and its excitation
spectrum [3]. 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 [4]. We observe a transition to a
state localized into a single lattice site and purely driven by interactions. Finally, we
uncover the parameter regimes where both droplet and soliton states can be achieved.
References
[1] 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)
[2] A. R. P. Lima and A. Pelster, Beyond mean-field low-lying excitations of dipolar Bose gases,
Phys.Rev. A 86, 063609 (2012)
[3] 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)
[4] G. Natale, T. Bland, S. Gschwendtner, L. Lafforgue, D. S. Gr¨un, 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)