QC:SCALE - Quantum Circuits: Systematically Controlling And Linking Emitters for integrated solid state photonics platforms

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This project investigates a promising solid state architecture that could be extended to build a quantum information processor. We focus on a well understood system, the NV-defect centre in diamond. This centre has a ground state spin that is well coupled to photons such that arrays of spins coupled by low loss waveguides can be envisaged. However the solid state brings increased decoherence and spectral non-uniformity compared to atomic systems. It also brings the prospect of building spin and photonic interfaces at scale, using nanofabrication. Here we aim to individually address solid-state emitters control their spin and make them spectrally indistinguishable thus ensuring high fidelity spin quantum bits linked by waveguides on a chip. While most of the focus of the solid-state quantum photonics community has been devoted to finding an ideal solid-state emitter that exhibits atom-like properties, relatively little effort has been spent on figuring out how one can build complex opto-electronic systems around them enabling precise optical and spin control. This is especially important, given that traditional top-down semiconductor manufacturing methods cannot be directly applied to such bottom-up systems. Since a fully error corrected quantum computer will need O(1E6) qubits and even near-term noisy intermediate scale quantum (NISQ) devices need O(1E2) to demonstrate computational quantum supremacy, there is an urgent need to establish that bottom up systems employing solid state emitters can be scaled up to be competitive with top-down fabricated systems (such as those employed for linear optics and superconducting circuits). The NV- centre provides a room-temperature quantum system with optical and spin degrees of freedom that can be accessed and manipulated and this room temperature readout makes the NV- centre attractive for rapid iteration and prototyping of devices, both in the electrical and optical domain. In addition, the ready availability of high coherence NV- centres in nanodiamond form allows us to directly implement bottom-up manufacturing methods, originally developed in the bio-chemistry domain, such as precision localisation and templated self-assembly to solid state quantum optics.