Precision measurement systems with relevance to frequency metrology and quantum readout techniques

This dissertation investigates techniques employed in the field of frequency metrology and the wider area of experimental physics, with applications towards engineered quantum systems. It covers the conception, development and characterisation of passive and active devices and readout systems, with a primary emphasis on phase noise measurement systems and methodologies for device characterisation up to the millimetre wave regime. We demonstrated how critical the intrinsic noise of active devices can be, most notably in the development of cryogenic sapphire oscillators and Maser frequency standards. The impact of device noise on frequency stability was explored, providing insights on approaches to improving performance.

Precision electromagnetic measurement techniques used in the characterisation of dielectric materials are also studied. The next generation of stable cryogenic oscillator technologies could be enhanced through the application of new materials with favourable electromagnetic and cryogenic properties. The use of a perturbative cavity measurement helped identify diamond as a potential dielectric material for future oscillators.

Ultimately the techniques developed and used throughout the thesis have been applied to enhance the readout capabilities of quantum-bit platforms that are used in quantum computing systems. Investigations were carried on both the control and readout of qubits viathe noise evaluation of waveform generators such as DACs and voltage sources. Readout sensitivity investigations also lead to the design of a cryogenic low noise amplification system.