Quantum Information with Mechanical Systems (QuIMS)

Recent progress in quantum technologies is underpinning significant advances across many sectors including defence, healthcare, and communication. At the same time, several challenges emerge as scientists strive to manipulate quantum states for signal enhancement, noise reduction, and ultimately quantum computing. A paradigmatic example is the recent demonstration of noise mitigation on a 127-qubit chip, but this has highlighted the limitations of coherence time, gate fidelity, and error suppression, as well as the challenge of connecting large numbers of physically separate qubits. Therefore, whilst improvements on established technologies remain crucial for scaling them up, the search for alternative routes towards quantum computing remains a most promising pathway towards useful quantum supremacy. Quantum Information with Mechanical Systems (QuIMS) explores the potential of mechanical resonators as a novel computing platform, both in support of existing qubit technologies (e.g., for quantum memories) and as a stand-alone qubit technology. To this end, we will build mechanical resonators with ultra-high coherence times that are manipulated with extreme precision by means of light fields. In this opto-mechanical system, we will attempt for the first time to embed several qubits in a single mechanical resonator, removing the need for cumbersome connecting wires that impedes, for instance, spin qubit devices. These mechanical qubits are expected to offer exciting opportunities to implement multi-qubit gates directly on a single resonator, which can greatly suppress the main sources of errors encountered in current platforms. The core novelty on which QuIMS leverages is the quadratic opto-mechanical coupling, which is needed for mechanical quantum computing but has so far been out of reach. We will design new devices that exploit symmetry and phononic crystals to suppress detrimental contributions such as heating of the mechanical resonators. We will work with graphene and carbon nanotubes that are uniquely suited to achieve the quadratic regime owing to their extremely low mass and strong interaction with radio-frequency light. The synergy of our complementary state-of-the-art facilities and of experimental and theoretical expertise at the Universities of Exeter and Lancaster are ideally suited to nurture the ambitious aims of this proposal. Upon demonstrating the quadratic opto-mechanical interaction, in collaboration with project partners including the National Quantum Computing Centre, we will explore the potential of our devices for applications such as signal enhancement, noise reduction, mechanical signal processing, filtering, and transduction. Hence, we will benchmark the performance of our opto-mechanical quantum systems against that of other known platforms such as superconducting, photonic, Rydberg and ion devices. Finally, we will investigate how our platforms can be combined with existing technologies, to be employed, e.g., as highly coherent memories (due to the extreme quality factors attainable by mechanical resonators).