GaSb/GaAs quantum rings as single photon sources

Quantum technologies are those which exploit the exotic properties of nature described by quantum mechanics to deliver
devices with unprecedented speed or accuracy compared with conventional technology, or even generate completely novel
technologies with new functionalities, which simply do not exist at present. Quantum cryptography is one such technology:
communication whose security is guaranteed by fundamental laws of quantum mechanics. The implementation of quantum
cryptography relies on the ability to generate single photons of light on demand. Several different physical systems have
been used to generate single photons, but very few of them are suitable for commercial production as they are impractical
and inconvenient. An ideal single photon source should be fast, cheap, operate at room temperature, and emit photons at
the wavelengths used in existing optical-fibre based telecommunications systems. In fact, a practical single photon source
is expected to look very like a type of semiconductor laser diode called a vertical cavity surface emitting laser (VCSEL). In
this year-long project we will assess the feasibility of mass-producing low-cost, room-temperature single photon sources
with telecom-wavelength emission by developing novel VCSEL devices whose active regions incorporate tiny
semiconductor nanostructures called self-assembled quantum rings. This will allow us to leap-frog a stage in the
development of practical, i.e. commercial, single photon sources, and to make a realistic assessment of their commercial
potential.

The exploitable results of this project are: (i) LED devices with GaSb/GaAs active material, (ii) VCSEL devices with
GaSb/GaAs active material, (iii) Academic IP relating to fundamental properties of GaSb/GaAs optical properties and
device design, and (iv) A UK supply chain from research to product feasibility in an important emerging technology. After a successful outcome of this project, the consortium intends to continue development into a fully realised commercial
product in the form of a packaged semiconductor chip. The most obvious form factor for this would be a TO-header-type
package typical of VCSEL devices currently used in datacoms applications. The current consortium embodies a full UK
supply chain for this product with CST Global ltd being the partner intending to manufacture and directly market and sell the
product. CST already has an existing supply chain for T0-header laser products. After the end of this programme the
consortium will require a further two year co-funded development project into which an end user or system integrator will be
added. CIP/Huawei have expressed an interest in this role. A further year of pre-production is envisaged before the
commercial product will be launched. The consortium intends to disseminate scientific advances in high impact journals
including Nature Photonics, Nature Communications and Applied Physics Letters, and will target talks at national and
international conferences such as UK Semiconductors, Photonics West [OPTO] and QD2016.
Direct economic benefit to the industrial members of the consortium is expected from the marketing and sales of the
resultant single photon source devices. Manufacturing of this product will be exclusively carried out in the UK until volumes
are high enough to justify to subcontracting the assembly stages. The top-line forecast revenue total of £5 million by 2020
split between IQE and CST at a projected return on investment of ~300%. A successful commercialisation of the
fundamental academic research at Lancaster University will have a positive impact on the research impact status
(REF2020) allowing it to attract enhanced funding. The UK technology community as a whole will be supported by the
generation of a quantum device supply chain.
Direct production of these high value quantum devices will result in safeguarding existing employment in the UK III-V
component manufacturing industry, a vital enabling high technology capability vital to many UK companies, of which CST
and IQE play a unique and critical part. Increased employment at CST would be needed to set up the product
manufacturing line.