Quantum Device Theory & Applications

Quantum device theory

The interpretation of experiments on quantum systems requires a strong theoretical base to create a seamless partnership between theory and experiment. Understanding single spin devices in silicon is daunting challenge, requiring the physics of the solid-state lattice to be coupled with an atomic level description of the donor electron and its orbital and spin states, and ultimately the details of external nanoelectronics gate control. The Centre has played a key role in developing the theoretical description necessary to describe donor based systems and nanostructures from ab-initio through to high-level multi-million atom simulations. The Quantum Device Theory and Applications Program will work closely with researchers from the other theoretical programs to implement state-of-the-art simulations of the devices fabricated and measured in the experimental programs.

Quantum computing and scale-up

The scale-up of qubits to a quantum computer is a highly non-trivial concept, particularly taking into account physical constraints of a given qubit implementation and the requirements of fault-tolerance and quantum error correction. The hierarchy of scales spans fundamental quantum device description at the physical level and the construction of quantum gates using available control, constraints on the implementation of quantum error correction and fault-tolerance and issues surrounding classical control and systems scale-up. The Quantum Device Theory and Applications Program will explore a number of issues around quantum computer scale-up for silicon and optical based qubits, as well as the opportunities presented at the optical-solid-state interface including entanglement generation, topological quantum codes, and quantum repeaters for communication.

Quantum device applications

The use of qubits as sensitive nano-scale probes is of great interest as a near-term application of quantum technology. Previously, Centre researchers have proposed decoherence measurements as a sensitive measure of magnetic field fluctuations. Spin systems in the solid state with long coherence times are promising candidate systems for such a quantum sensor. Additionally, understanding in detail how these spin qubits systems behave in the spin-environment of the solid-state in tern provides valuable information and guidance to the experimental programs performing measurements on spin qubits and in linger term how these systems will behave under quantum error correction. The Quantum Device Theory and Applications Program will explore in detail the quantum dynamics of spin probe systems with a view to developing a range of near-term quantum sensing applications. The nitrogen-vacancy (NV) centre in diamond in particular is a promising candidate qubit sensor, particularly for room temperature biological applications.