This project aims to investigate a completely new approach to creation of coherent matter in special semiconductor microcavities. We have already produced a theoretical model which strongly suggests that a non-equilibrium Bose-Einstein condensate may be produced in the interaction of specially tailored optical pulses with a microcavity containing quantum dots. We need to extend this model to include more realistic details of the physics, and to build an experiment which is capable of detecting the special signatures in the emission spectrum which would confirm the presence of the condensate in the microcavity. The theoretical work will extend the present understanding to include relevant physics such as multiple levels and disorder, as well as carefully mapping out the limits to the expected behaviour. The experiment will make it possible to carry out measurements of the optical emission from a microcavity under conditions in which the exciting light has a special frequency structure, and enters the cavity at an arbitrary angle. Likewise the emission can be sampled with sub-picosecond time resolution and collected at an arbitrary angle, so special effects such as the expected concentration of the condensate into the k=0 state can be probed through dynamical and angular signatures. The issues probed lie at the heart of studies of coherent matter, which increasingly appears to offer rich prospects both for new physics, and ultimately, new technologies.

Quantum computing is now widely regarded by many in academia, governments and industry to represent a major new frontier in information technology with the potential for a disruptive impact. Many different materials and approaches have been explored, with a narrowing of focus in recent years on scalable implementations based on solid state platforms. In particular, there is now strong evidence that silicon, the primary platform technology for today’s processor technology, inherently possesses many key properties that make it advantageous for quantum computing. Two types of qubit based on spins in silicon nano-devices made in academic research labs have already been reported with demonstrated high-fidelity operation. Our project builds on this success and aims to take this technology to the next readiness level by showing that silicon-based qubits can be realised within a full CMOS platform, using the 300mm-scale fabrication facilities in our consortium. In doing so we will demonstrate the true potential of silicon based qubits in terms of scalability and manufacturability. Our focus is on distilling the silicon device design down to the simplest core element necessary to demonstrate qubit behaviour, in order to lay the foundation for a scalable technology. We will design, model and fabricate these qubit devices, and then benchmark them using key operating parameters. Our attention is not limited at the lowest level technology layer where the qubits reside, and includes higher control layers necessary to operate such devices, including demonstrating strategies for achieving local control and readout in large-scale arrays without cross-talk and developing cryo-CMOS electronics to support the qubit operation. Both of these may be spun-out and yield their own technological impacts. Thus, our holistic approach offers a wider opportunity to harness the tremendous proven capabilities of integrated CMOS technology to become a key driver of quantum technology development.