Surface acoustic waves (SAWs) propagate in piezoelectric materials and are generated by interdigital transducers (IDTs). SAW devices have applications in a variety of fields, under which...Show moreSurface acoustic waves (SAWs) propagate in piezoelectric materials and are generated by interdigital transducers (IDTs). SAW devices have applications in a variety of fields, under which telecommunication, biology and chemistry. The context of SAW devices in this research project is in quantum acoustics, in which the underlying idea is that quanta of sound waves (single phonons) can be used to transfer quantum information between different systems. As these systems often operate at GHz frequencies and are fabricated on Gallium Arsenide (GaAs) substrates, the goal of this research project is to fabricate (using electron-beam lithography) and characterize 1 GHz SAW devices on GaAs. The SAW emission by the IDTs is measured in the frequency domain, where good agreement is found with the coupling of modes model, allowing us to extract the SAW amplitude, the SAW velocity and the reflection coefficient of the IDT fingers. The IDTs are also measured in the time domain, were good agreement is found with the findings of the frequency domain measurements. Finally, a first step is made towards SAW resonators, which can enhance the SAW amplitudes significantly. This amplitude enhancement is crucial for quantum acoustics experiments, as high coupling between quantum dots and SAWs is needed. This project can therefore be thought of as the foundation for future quantum acoustics experiments.Show less
Asymmetric public key encryption uses long computation times of certain mathematical calculations to ensure security. But future quantum computers could do these calculations in a matter of minutes...Show moreAsymmetric public key encryption uses long computation times of certain mathematical calculations to ensure security. But future quantum computers could do these calculations in a matter of minutes rather than centuries. Quantum mechanical effects can be leveraged to create fundamentally secure key distribution protocols like the ideal BB84 protocol or the decoy states BB84 protocol. The ideal BB84 protocol, however, currently has too much signal loss at km range distances to be practical. One proposed solution to increase the key rate is by using decoy states. We simulate an imperfect BB84 protocol to confirm that the key rate for a realistic non-perfect BB84 scheme can be increased by using decoy states. We also demonstrate a practical method using an acousto-optical modulator (AOM) to create a pulsed laser that contains two types of pulses, each with a distinct mean photon number. Our results show that acousto-optic modulation of µWscale pulses results in accurate pulses with just a 0.14% deviation between light pulses with the same input parameters. We conclude that acoustooptic modulation should be sufficiently accurate to create decoy pulses for a practical decoy state BB84 system.Show less
The goal of this research is to find out the effects of certain disturbances on the results of the Hanbury Brown-Twiss (HBT) experiment. The HBT experiment was performed to demonstrate the working...Show moreThe goal of this research is to find out the effects of certain disturbances on the results of the Hanbury Brown-Twiss (HBT) experiment. The HBT experiment was performed to demonstrate the working principles of the intensity interferometer. In order to model the disturbances a computer model of the HBT experiment was developed in Python. A total of three disturbances were modeled; detector efficiency, detector jitter, and detector dead time, and two types of light were modeled; Coherent and singlephoton light. Numerical experiments were performed to measure the effect of the disturbances on the measurements. For detector efficiency and dead time, a clear effect could be observed, but for the detector jitter, the results were dependent on the type of light being used.Show less
