Characterisation of a Multiplexed Photon Pair Source

Robert J. A. Francis-Jones

Takayuki Kiyohara, Ryo Okamoto, Shigeki Takeuchi

Robert J. A. Francis-Jones, Rowan A. Hoggarth, Peter J. Mosley

We present the construction and characterisation of a spatially multiplexed photonic crystal fibre source of high-purity heralded single photons at 1560nm. We demonstrate performance improvements from multiplexing two sources.

Iman Jizan

In quantum photonics, the requirement for photon pairs with specific quantum states has led to a demand for a fast, high resolution and accurate characterisation of photon pair sources. However, current quantum methods of characterisation suffer from limited accuracy and resolution, and only consist of intensity measurements that prevent access to phase-sensitive measurement photon pairs. A promising tool that addresses these challenges, uses the classical analogue of nonlinear processes to stimulate photon generation, yielding much higher count rates that allows for a higher resolution and accurate photon pair source characterisation. Furthermore, this classical measurement allows for an innovative method to perform full phase-sensitive quantum tomography of photon pair sources that was previous thought to be experimentally challenging to obtain. This thesis examines and compares the quantum and classical method of characterisation of spectral correlations in χ^3 nonlinear devices; namely two integrated silicon nanowires, and a highly nonlinear fibre. In the first study, we use stimulated nonlinear process to confirm the speed-up of characterisation of photon pairs and demonstrate that additional resolution is gained when compared to the traditional coincidence measurements with no increase in measurement time. By applying this technique with phase-sensitive amplification to another identical silicon nanowire, the first phase sensitive measurements are presented showing details that are otherwise hidden in traditional intensity measurements. Furthermore, phase-sensitive measurement of a highly nonlinear fibre shows that phase-sensitive measurements have excellent sensitivity to small features when compared to the traditional intensity measurements.

Markus Rambach

Bryn A. Bell, Gil Triginer, Chris Wade +2 more

Multi-photon interference is observed between frequency channels in the higher-order emission from individual photon pair sources, using pulse shaping of the pump laser. I will also discuss applications to phase-sensitive spectral characterisation of pair sources.