In this research project, we attempt to develop numerical simulation models to investigate surface acoustic waves (SAWs) and how they can be efficiently excited using interdigital transducers (IDTs...Show moreIn this research project, we attempt to develop numerical simulation models to investigate surface acoustic waves (SAWs) and how they can be efficiently excited using interdigital transducers (IDTs). These devices already find use in applications such as filtering devices for mobile communication systems. We identified the equation of motion in solids, Gauss’ law of electrostatics and the piezoelectric constitutive equations combined with material properties as the basic physics required to model IDTs. Based on these equations, we developed 2D and 3D finite element method (FEM) simulations in COMSOL, with lithium niobate and gallium arsenide as substrate materials, which we used to investigate the IDT frequency response. We also investigated the transient response of IDTs. Our results are in good agreement with analytic theory, which validates our model and approach. These models can now be used to optimize IDT device designs. Lastly, we propose and implement the first steps toward an optical setup based on a Michelson interferometer to detect surface acoustic waves.Show less
Fabry-Perot cavities are generally used in cavity QED. Due to technical restraints it is prudent to evaluate the ability to create open micro cavities in the weakly coupled regime. We have focussed...Show moreFabry-Perot cavities are generally used in cavity QED. Due to technical restraints it is prudent to evaluate the ability to create open micro cavities in the weakly coupled regime. We have focussed on building the foundation for the weakly coupled cavity by charactarizing a macroscopic cavity in detail. We analyse the cavity effects, for the fundamental and higher order modes. Using the primary mode of a plane-curved mirror cavity we found the Free Spectral Range in multiple ways, and looking at transmission spectra as a function of wavelenght we found a spectrum of transmission peaks with a predictable mode ordering. Thus the cavity was found to be consistent with theory. The system has been improved upon by presenting an extensive model for modematching. The model is capable of determining the coupling efficiency after introducing a lens with any focal length and possible position. With the model we were able to find a setup configurations with near unity coupling efficiency to the fundamental mode of the cavity.Show less
To test whether a proposed interference experiment with parametric amplifiers to test spontaneous wave function collapse is feasible we measured the spectra of Traveling Wave Parametric Amplifiers ...Show moreTo test whether a proposed interference experiment with parametric amplifiers to test spontaneous wave function collapse is feasible we measured the spectra of Traveling Wave Parametric Amplifiers (TWPAs) and came to the conclusion that that non-tested TWPAs were shorted and had major losses. TWPAs that were measured before also showed major losses. However, we did measure some effects of the expected nonlinear behavior of the Josephson junctions and the creation of idler photons. We have improved a calorimeter and reduced its equilibrium temperatures from 63.2 and 72.1 mK to 40.8 and 44.0 mK by reducing the thermal contact resistances. The calorimeter should be improved further before we can make use of it and measure the dissipation in samples such as the TWPAs. Furthermore, we did simulations on the signal and idler visibilities of the interferometer for a parametric gain up to 13.4 dB and losses in the TWPA up to 6 dB. We found that for large parametric gain the signal and idler visibility converged to a single value dependent of the losses in the TWPA. For all losses we tested, the visibilities were always greater than 0. If a collapse has happened the visibility would be 0. This means that as long as the losses in the TWPA are less than 6 dB and both TWPAs are exactly the same, we can always see from the measured visibilities if a collapse has happened.Show less
