Tunable superconducting resonators, subharmonic oscillations and manipulation of microwaves
Doctoral thesis, 2018
The first project I present is on subharmonic oscillations. Here, the SQUID in a tunable resonator is driven with an external signal at an integer multiple of the frequency w. When w is placed slightly below the first resonator mode, I show generation of radiation at w, which is known as frequency down-conversion. In my measurements, subharmonic oscillations have been detected from period doubling up to period quintupling. For the specific case of period tripling, theory is developed and I show good agreement between theory and experiments.
The second project of the thesis is on a doubly tunable resonator. Here, I show creation of a superconducting resonator with two independently tunable boundary conditions. The idea with this system is to operate the resonator in a breathing or a translational mode and compare the two. For static dc magnetic flux the performance is very good. As a second step, I perform fast modulation of both SQUIDs to generate radiation. Even though some of the measurement results are promising, I also show some contradicting observations. These indicate that the actual modulation mechanism of the SQUID is not pumping of the magnetic flux in the SQUID loop as intended, but rather direct current driving of the SQUID. However, the system remains a promising idea for microwave manipulation and creation of interesting non-classical states.
As a possible application of the doubly tunable resonator, I present a theory proposal on how to use it for measurements on relativistic effects. By using the tunability of the resonator boundary conditions, the resonator can simulate a space rocket and time dilation could be measured. However, due to the crosstalk problems in the doubly tunable resonator this experiment was never realized.
Finally, I finish the thesis by presenting a design for a tunable microwave coupling. Papers E and F show a high on-off ratio for the coupler and demonstrate how it can be used for storage of microwave signals. Furthermore, the tunable coupler can be used to shape a microwave signal by tuning the strength of the coupling.
tunable superconducting resonators
driven nonlinear systems
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Device Physics
Period-tripling subharmonic oscillations in a driven superconducting resonator
Physical Review B,; Vol. 96(2017)p. 174503-
Svensson, I-M., Bengtsson, A., Bylander, J., Shumeiko, V., Delsing, P. Period multiplication in a parametrically driven superconducting resonator
Twin paradox with macroscopic clocks in superconducting circuits
Physical Review A - Atomic, Molecular, and Optical Physics,; Vol. 90(2014)p. Art. no. 052113-
Storage and on-demand release of microwaves using superconducting resonators with tunable coupling
Applied Physics Letters,; Vol. 104(2014)p. Art. Nr. 232604-
Pierre, M., Sathaymoorty, S., Svensson, I-M., Johansson, G., Delsing, P. Resonant and off-resonant microwave signal manipulations in coupled superconducting resonators
Microwave photon generation in a doubly tunable superconducting resonator
Journal of Physics: Conference Series,; Vol. 969(2018)
Paper in proceeding
Areas of Advance
Nanoscience and Nanotechnology (SO 2010-2017, EI 2018-)
Condensed Matter Physics
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4372
Chalmers University of Technology
Opponent: Prof. P. J. Meeson, Department of Physics, Royal Holloway, University of London, United Kingdom