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We propose a new approach to natively embedding graph colouring problems onto neutral atom arrays using multiple Rydberg states each representing a unique colour. Graph colouring arises in a wide range of industrially relevant optimisation problems from sharing data across a wifi network to scheduling tasks and planning workloads. Using multiple Rydberg states enables efficient encoding of this problem onto quantum hardware and provides a new direction for near-term applications of neutral atom quantum computing. For more details see arXiv.2504.08598.
We present a scheme for speeding up quantum measurement. The scheme builds on previous protocols that entangle the system to be measured with ancillary systems. In the idealised situation of perfect entangling operations and no decoherence, it gives an exact space-time trade-off meaning the readout speed increases linearly with the number of ancilla. We verify this scheme is robust against experimental imperfections through numerical modelling of gate noise and readout errors, and under certain circumstances our scheme can even lead to better than linear improvement in the speed of measurement with the number of systems measured. This hardware-agnostic approach is broadly applicable to a range of quantum technology platforms and offers a route to accelerate midcircuit measurement as required for effective quantum error correction. For more details see Phys. Rev. Lett. 134, 080801 or arXiv:2407.17342.
Neutral atom arrays have emerged as a versatile platform towards scalable quantum computation and optimisation. In this paper we present first demonstrations of weighted graph optimization on a Rydberg atom array using annealing with local light-shifts. We verify the ability to prepare weighted graphs in 1D and 2D arrays, including embedding a five vertex non-unit disk graph using nine physical qubits. We find common annealing ramps leading to preparation of the target ground state robustly over a substantial range of different graph weightings. This work provides a route to exploring large-scale optimisation of non-planar weighted graphs relevant for solving relevant real-world problems. For more details see PRX Quantum 6, 010301 (2025) or arXiv:2404.02658.
We have performed theoretical work on algorithmic benchmarking to evaluate the performance of near-term neutral atom processors accounting for realistic gate errors and atom loss. We show that for a 9 qubit system a quantum volume of 29 is attainable, the maximum possible for this size of processor, highlighting the viability of using near-term neutral atom hardware for small-scale algorithms. For more details see arXiv:2402.02127.
We present an analysis of interspecies interactions between Rydberg d-states of rubidium and cesium. We identify the Förster resonance channels offering the strongest interspecies couplings, demonstrating the viability for performing high-fidelity two- and multi-qubit CkZ gates up to k=4, including accounting for blockade errors evaluated via numerical diagonalization of the pair-potentials. Our results show d-state orbitals offer enhanced suppression of intraspecies couplings compared to s-states, making them well suited for use in large-scale neutral atom quantum processors. For more details see arXiv:2401.02308.
Congratulations to Dr Jonathan Pritchard on receiving a prestigious RAEng Senior Research Fellowship with M Squared Lasers to develop fault-tolerant neutral atom quantum computers. For more information see the project page QuERy.
We have demonstrated high-fidelity randomised benchmarking of single qubit microwave gates across an array of 225 atoms, and non-destructive readout of up to 49 atoms. We achieved an average gate error of 8×10-5 which is below the threshold for fault tolerant operations, highlighting the viability of neutral atoms for scalable computing. For more details see our paper Phys. Rev. Lett. 131, 030602 (2023) [arXiv].
We have demonstrated the UK’s first neutral atom two-qubit gate using a novel protocol based on electromagnetically induced transparency originally proposed back in 2008. We achieve a corrected CNOT gate fidelity of 0.82(6), mainly limited by available laser power. For more details see Phys. Rev. Lett. 129, 200501 (2022).
