Collective modes and superfluidity of a two-dimensional ultracold Bose gas

Abstract

The collective modes of a quantum liquid shape and impact its properties profoundly, including its emergent phenomena such as superfluidity. Here we present how a two-dimensional Bose gas responds to a moving lattice potential. In particular we discuss how the induced heating rate depends on the interaction strength and the temperature. This study is motivated by the recent measurements of Sobirey {\it et al.} arXiv:2005.07607 (2020), for which we provide a quantitative understanding. Going beyond the existing measurements, we demonstrate that this probing method allows to identify first and second sound in quantum liquids. We show that the two sound modes undergo hybridization as a function of interaction strength, which we propose to detect experimentally. This gives a novel insight into the two regimes of Bose gases, defined via the hierarchy of sounds modes.

Main text: 7 pages + 6 figures and Supplementary text: 5 pages + 4 figures

References in corpus (8)

• Extension of Bogoliubov theory to quasi-condensates
• Superfluid behaviour of a two-dimensional Bose gas
• Observation of the Berezinskii-Kosterlitz-Thouless Phase Transition in an Ultracold Fermi Gas
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• Critical velocity for superfluid flow across the BEC-BCS crossover
• Roton-Maxon Excitation Spectrum of Bose Condensates in a Shaken Optical Lattice
• The critical velocity in the BEC-BCS crossover
• Observation of first and second sound in a BKT superfluid

Cited by in corpus (9)

• Observation of the BKT Transition in a 2D Bose Gas via Matter-Wave Interferometry
• Superfluidity of a laser-stirred Bose-Einstein condensate
• Effects of quantum fluctuations on the low-energy collective modes of two-dimensional superfluid Fermi gases from the BCS to the Bose Limit
• Berezinskii-Kosterlitz-Thouless phase transition with Rabi-coupled bosons
• Thermal suppression of demixing dynamics in a binary condensate
• First and second sound in a dilute Bose gas across the BKT transition
• Designing Atomtronic Circuits via Superfluid Dynamics
• Realizing an Atomtronic AQUID in a Rotating-Box Potential
• Josephson Dynamics in 2D Ring-shaped Condensates