ISBN 978-3-8439-4599-8

978-3-8439-4599-8, Reihe Physik

Tobias Wagner
Realization of a Hybrid Quantum System Consisting of Ultra-cold Atoms and a Nanomechanical Oscillator

141 Seiten, Dissertation Universität Hamburg (2020), Softcover, B5

Zusammenfassung / Abstract

In the past years, there has been significant progress in the field of quantum hybrid systems, which is a field dealing with the combination of multiple quantum systems. Such hybrid systems allow to observe quantum mechanical effects in macroscopic and mesoscopic systems. Furthermore, hybrid systems allow utilizing the advantages of both subsystems in quantum technologies, such as quantum communication or metrological applications. In the framework of this thesis, measurements on a quantum hybrid system consisting of ultra-cold rubidium-87 atoms and a trampoline oscillator inside a cryostat will be presented. The interaction between both subsystems is mediated by an optical lattice.

In the following, I am going to present the results of three measurements that were performed on the hybrid system. Firstly, I will present active feedback cooling of the oscillator’s fundamental mode. The feedback is exerted by the radiation pressure force of a laser beam that is modulated using a signal derived from the position measurement of the oscillator.

Secondly, I will present an experiment where the fundamental mode of the mechanical oscillator was sympathetically cooled by coupling it to a sample of laser cooled atoms. The oscillator mode is sympathetically cooled.

Thirdly, coupling between the mechanical oscillator and ultra-cold atoms was realized. I will present an experiment where a Bose-Einstein-condensate was loaded into the optical lattice used for coupling. Subsequently, atomic excitations occurring in the lattice are used to characterize the hybrid coupling between the oscillator mode and the atoms.