Neutral atom quantum computers have emerged as one of the most promising platforms for quantum information processing [1], with a major advantage over competing technologies arising from the ability to scale to large numbers of identical qubits as required for performing practical quantum computing. These qubits, created from individually trapped atoms, can be coupled to highly excited Rydberg states to engineer strong, long-range interactions for high fidelity gate operations [2] or continuous time analogue optimisation protocols [3]. Combining this with the ability to dynamically reconfigure atoms to implement arbitrary connectivity, these platforms can allow demonstrations of logical qubit encodings and quantum error correction [4]. This approach provides a viable route to realising the potential advantages of quantum computing in enhancing application areas such as quantum chemistry and material science, as well as accelerating hard classical problems such as factorisation or optimisation.

This PhD project will use the Strathclyde neutral atom quantum computing platform, SQuAre, to advance the development of logical qubit encodings suitable for performing quantum error correction, and demonstrate fault-tolerant quantum algorithms [4].  The SQuAre platform has already demonstrated world-record single qubit gate fidelities [6] and pioneered work on weighted graph optimisation problems [3] using arrays of up to 255 qubits. An early goal of this PhD project will involve upgrading the hardware to implement high-fidelity state-selective readout scheme [4] that can provide efficient measurement without ejection of atoms as used in many experiments currently. This advance will enable fast cycle times by promoting re-use of atomic qubits, as well as facilitating real-time loss-detection to allow rapid replacement of missing atoms.

Using this non-destructive readout technique, we will investigate different logical qubit encoding schemes in which quantum information is stored collectively across an ensemble of physical qubits. By characterising the performance of each encoding, we will identify the best encodings for implementing quantum error correction routines and use this to demonstrate fault-tolerant implementation of quantum algorithms relevant to near-term quantum applications.

This project is closely aligned to the QCi3 Quantum Computing hub, and will benefit from close collaboration with the team of Joschka Roffe at Edinburgh who is a world expert in quantum error correction and decoding techniques.