Title of seminar: Fast compression of a Bose-Einstein condensate and the new experiment for 2D Bose gases

Abstract:

In this seminar, I will first present the latest results on the evolution of a Bose-Einstein condensate after an abrupt compression where our preliminary analysis indicates an enhanced three-body losses.

Next, I will focus on describing a new experimental setup which aims to produce a 2D Bose gas of potassium-39 and explore the dynamics of quantum vortices in two dimensions.

Quantum hydrodynamics and turbulence in atomic BECs

Quantum hydrodynamics and turbulence [1] have been long studied in superfluid helium since 1950’s, and in atomic Bose-Einstein condensates (BECs) too. In this talk, I would discuss the important topics of atomic BECs.

Introduction

We will overview briefly characteristics of quantum hydrodynamics and turbulence compared with those of classical turbulence.

Single-component BECs

Turbulence likes isotropy [2] and rotation causes anisotropy. Such competition of two contradictory effects has been studied in classical turbulence [3]. Rotation in a quantum fluid forms a vortex lattice along the rotational axis and gives other interesting effects. There are not so many experimental works [4-6] on rotating quantum turbulence, and theoretical numerical studies are also limited [7]. I will discuss rotating quantum turbulence of BECs [8].

Two new scenarios for quantum friction: chiral media and rotating molecules

In the first scenario, we study the quantum friction experienced by a polarizable charged particle moving with parallel motion to a chiral medium-vacuum interface. We employ macroscopic quantum electrodynamics ^1,2 to obtain the Casimir–Polder frequency shift and decay rate. These results are a generalization of the respective quantities to matter being insensitive to parity². By examining the non-retarded and retarded limits we find that the an effective optical rotatory strength is relevant for a non-vanishing frequency shift and decay rate. For the second scenario, we investigate the rotational motion of diatomic molecules in free space interacting with the quantum electromagnetic field³. Using macroscopic quantum electrodynamics² we obtain the rotation-dependent decay rates of the molecule. By analyzing the behavior of the resulting rates at zero and finite temperature, we find a connection between the decelerating rotational dynamics and quantum friction.

¹ Stefan Yoshi Buhmann, David T. Butcher and Stefan Scheel. New Journal of Physics 14, 083034 (2012).
² S. Y. Buhmann. Dispersion Forces II. Many-Body Effects, Excited Atoms, Finite Temperature and Quantum Friction. (Springer, Berlin Heidelberg, 2012).
³ Stefan Yoshi Buhmann, M. R. Tarbutt, Stefan Scheel, and E. A. Hinds, Phys. Rev. A 78, 052901 (2008).

Non-stationary quantum many-body dynamics