In theory, quantum states of lights can be used to perform measurements with a level of precision beyond that which can be attained with their classical counterparts. In practice,they can only do so when the components that we use to generate, manipulate and measure them, operate beyond specific thresholds. In this thesis, we seek to address different obstacles that hinder our ability to fully exploit quantum-metrological schemes. We mainly focus our attention in quantum-enhanced optical transmission measurements. For this we make use of photon pair sources and take advantage of the photon number correlations of the sources to suppress noise in parameter estimation. With this approach we are able to reach a level of precision beyond the shot-noise limit without the use of post-selection. We achieve this by implementing feed-forward and using a CCD camera with high detection efficiency. We have been able to obtain measurements of transmission with a maximum factor of advantage of 1.66 when compered to an ideal classical experiment using a noiseless coherent source and a 100% efficient detector. We have also studied the roll of photon distinguishability in quantum-enhanced phase estimation, where we have performed experiments with two and four-photons states controlling their level of distinguishability and we demonstrate that fully indistinguishable photons are not required to obtain quantum-enhanced measurements.
|Date of Award||25 Sep 2018|
- The University of Bristol
|Supervisor||Jonathan C F Matthews (Supervisor) & Jeremy O'Brien (Supervisor)|