Towards flux-tunable superconducting coplanar waveguide resonators for inductive coupling to levitated superconducting particles

Avan Mirkhan, MPNAT Nanotechnology, presents his master thesis with the title Towards flux-tunable superconducting coplanar waveguide resonators for inductive coupling to levitated superconducting particles

Examiner: Witlef Wieczorek


​Abstract:

Superconducting magnetic levitation is a promising technique to study potential limits of quantum mechanics for mesoscopic objects due to the levitated object being extremely isolated from the environment. Using optomechanics techniques, the center-of-mass motion of a levitated particle can be controlled and cooled down to its motional ground-state thereby bringing it into the quantum regime. This would enable macroscopic quantum experiments as well as ultra-sensitive force and acceleration sensing. In order to realize this, the motion of the particle's center-of-mass would be coupled to a flux-tunable superconducting resonator, which would allow control of the particle motion through the state of the resonator.

 

This thesis presentation investigates the microwave properties of superconducting coplanar waveguide (CPW) resonators. At first, non-flux tunable CPW resonators were fabricated from Aluminum and Niobium and measured in a cryostat at mK temperatures. The best performing CPW resonators achieved unloaded quality factors of ~10^5 and ~10^6 at 10^6 average number of intra-cavity photons for Aluminum and Niobium, respectively. The quality factors of these resonators were found to be similar to the state-of-the-art. Subsequently, flux-tunable resonators were fabricated by embedding a SQUID into Aluminum-based CPW resonators.

The flux tunability of these resonators was studied and was found to be much lower than expected. The reason for the low tunability was identified to lie in issues with the fabrication process of the Josephson junctions of the embedded SQUID. Based on these identified issues, suggestions have been proposed to improve upon the fabrication of flux-tunable CPW resonators, such that in the future the desired frequency modulation through a change in magnetic flux can be observed.​

​Zoom: https://chalmers.zoom.us/j/62026785935, Password: 509410
Category Student project presentation
Location: Kollektorn, lecture room, Kemivägen 9, MC2-huset
Starts: 16 August, 2022, 13:15
Ends: 16 August, 2022, 14:00

Page manager Published: Mon 08 Aug 2022.