Engineering four-wave-mixing frequency conversion in photonic crystal fibre for quantum networks

• Main Author: Parry, Charlotte
• Format: Dissertation
• Language: English
• Published: University of Bath 2023

Quantum networks provide the possibility of advancing global communication, security and computing, and have become the next biggest goal in information technology, with some of the world's largest companies investing in quantum technology. Underpinning this goal is the need for a quantum interconnect, a way to connect quantum nodes over large distances to create a multinational network and transmit quantum information in a fast and reliable way. Exisiting fibre-optic infrastructure would provide a fast and high bandwidth method of distributing quantum entangled photons, and as a result there have been many recent advancements in the generation and manipulation of photons for quantum systems. However many of these node systems operate at completely different optical wavelengths, some that are not compatible with low-loss transmission in optical fibre. Frequency conversion of single photons in an adaptable and robust way is needed for photonic quantum networks to succeed. Presented in this thesis is one method of tunable frequency conversion, via four-wave-mixing in a photonic crystal fibre (PCF) device. I characterize a previous experiment demonstrating a fibre-based frequency conversion device. By looking in more depth at the group velocity profile of this fibre design I describe how the design can be adapted to convert between a significantly wider range of wavelengths to low-loss telecommunications bands. This thesis presents results from a PCF I fabricated to be capable of broadband conversion. I demonstrate a working conversion setup and show that the conversion is maintained when tuning the pump wavelength.