Unlocking the Potential of Fibre-Based Single-Photon Sources

Project: Research council

Project Details


Huge computational power. 100% secure communications. Ultra-precise measurements. All this (and more) can be yours - and all you require is the ability to make photons one-by-one! What could be simpler? Photons are fundamental particles of light, and there are lots of them about. Billions are entering your eyes every second as you read this. However, in recent years, we have begun to develop the tools and techniques required to generate and manipulate single photons one at a time. Not only has this enabled experiments that demonstrate the counter-intuitive nature of the hidden quantum world underlying the one we inhabit, but also it has heralded a revolution in the way in which we process information and communicate with one another. Unlike the bits of information that are processed by a normal computer or transmitted through the fibre optic networks that make up the internet, single photons have the capability to carry quantum information: a single photon can exist in a superposition state that is both 1 and 0 simultaneously, and two single photons in remote locations can be closely linked through quantum entanglement. These additional capabilities can be applied in three critical areas: computation can be sped up so that tasks that are intractable even for a supercomputer, for example the simulation of complex systems such as new pharmaceuticals, could be carried out easily by a sufficient number of single photons; communications using single photons allows provably secure information transmission and the detection of any attempted eavesdropping; and measurements made with entangled states of light composed of single photons can increase precision beyond that possible with conventional light sources such as lasers. Significant progress has been made towards achieving these objectives in research laboratories worldwide. However, generating the single photons needed for quantum information processing is a difficult task in itself. Current implementations of small-scale photonic quantum processors are based on single photon sources that are very unreliable - typically these sources function correctly only approximately 1% of the time. This is a significant problem when trying to scale experiments up, something that must be done now in order to run useful algorithms or transmit quantum information at high data rates. These tasks require many single-photon sources each to produce one photon at the same time - this is not possible with the current generation of single-photon sources as the probability of at least one source failing increases exponentially with the number of sources. Hence current state-of-the-art experiments using just four sources must run for days at a time to capture only a few hundred occasions when all four have fired together. The aim of this project is to demonstrate a method for dramatically improving the performance of single-photon sources and go some way towards solving this scalability problem. We will build an optical fibre network of individual single-photon sources and combine their outputs using a fast optical switch to create one "multiplexed" single-photon source. The multiplexed source will have significantly enhanced performance relative to an individual source while retaining all its favourable characteristics such as room-temperature operation and ease of use. Furthermore, the multiplexed source will form the building-blocks of a future ultra-high-performance source: theoretical studies have shown that a few of these blocks together provide the required resource for almost perfect single-photon source operation.
Effective start/end date17/05/1316/05/15


  • Engineering and Physical Sciences Research Council


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