Welcome to the Rydberg Atom Quantum Technologies team lead by Prof. Jonathan Pritchard, an RAEng Senior Research Fellow at the University of Strathclyde.
Overview
Rydberg atoms are atoms excited to extremely large principal quantum numbers resulting in giant atoms offering exaggerated properties including
enormous electric-dipole moments in the microwave frequency range and strong, tuneable long-range interactions. Our research is focused on developing new
quantum technologies that exploit these properties to develop scalable platforms for quantum computation and optimisation, and atomic gas sensors for precision
microwave field detection and imaging.
Please contact jonathan.pritchard@strath.ac.uk if you are interested in working in within one of our research areas – we have both PhD and PDRA positions available (see below for details) across focused on developing neutral atom quantum computers based on scalable arrays of neutral atoms.
This project, supported by a Royal Academy of Engineering Senior Research Fellowship and M Squared Lasers, seeks to develop a new experiment focused on creating dual-species arrays of Cs and
Rb for quantum error correction. This is integrated within a 4K closed-cycle cryostat to obtain extended trap lifetime for scaling to large numbers of qubits, and will focus on exploiting long-range dipole interactions between Rydberg
states of each species to enable mid-circuit, non-destructive readout and generation of topologically protected logical qubits as a route towards fault tolerant digital quantum computing.
This project is an EPSRC Prosperity Partnership with M Squared Lasers that aims to develop a new platform for quantum computing based on scalable arrays of neutral atoms that is able to overcome the challenges to scaling of competing technologies. We will develop new hardware to cool and trap arrays of over 100 qubits that will be used to perform both analogue and digital quantum simulation by exploiting the strong long-range interactions of highly excited Rydberg atoms. Together with the quantum software team lead by Prof. Andrew Daley, we will design new analogue and digital algorithms tailored for the neutral-atom platform to target industrially-relevant computation and optimisation problems.
ARC:Alkali Rydberg Calculator
An open-source python library for calculating properties of Alkali Rydberg atoms developed with Nikola Sibalic, Charles Adams and Kevin Weatherill at JQC in Durham. Full details on the arXiv:1612.05529 - download source from GitHub.
In collaboration with the theory team lead by Prof. John Jeffers and supported by DSTL, we are developing new approaches to quantum enhanced LIDAR by creating a compact optical frequency comb source for pumping birefringent optical fibres and exploring a new log-likelihood metric to perform quantum enhanced stand-off detection and range-finding.
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.
Our results demonstrating a correlated pair-source to perform target detection and range-finding to show the resilience of quantum-enhanced lidar to classical jamming have been published in Optics Express.
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.
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).
We have developed a robust protocol for implementing high-fidelity multiqubit controlled phase gates (CkZ) on neutral atom qubits coupled to highly excited Rydberg states via adiabatic rapid passage (ARP). We find a CCZ gate with fidelity F > 0.995 for three qubits and CCCZ with F > 0.99 for four qubits is attainable in ∼ 1.8 μs via this protocol. For more details see our paper in QST.
D. Lall, A. Agarwal, W. Zhang, L. Lindoy, T. Lindström, S. Webster, S. Hall, N. Chancellor, P. Wallden, R. Garcia-Patron, E. Kashefi, V. Kendon, J. Pritchard, A. Rossi, A. Datta, T. Kapourniotis, K. Georgopoulos, I. Rungger,
A review and collection of metrics and benchmarks for quantum computers: definitions, methodologies and software.
(2025).
C. Corlett, I. Cepaite, A. Daley, C. Gustiani, G. Pelegrí, J. Pritchard, N. Linden, P. Skrzypczyk,
Speeding up quantum measurement using space-time trade-off.
Physical Review Letters134,
(2025).
A. de Oliveira, E. Diamond-Hitchcock, D. Walker, M. Wells-Pestell, G. Pelegrí, C. Picken, G. Malcolm, A. Daley, J. Bass, J. Pritchard,
Demonstration of weighted graph optimization on a Rydberg atom array using local light-shifts.
PRX Quantum6,
(2025).
P. M. Ireland, D. M. Walker, J. D. Pritchard,
Interspecies Förster resonances for Rb-Cs Rydberg d -states for enhanced multi-qubit gate fidelities.
Physical Review Research6,
(2024).
K. McDonnell, L. F. Keary, J. D. Pritchard,
Demonstration of a Quantum Gate Using Electromagnetically Induced Transparency.
Physical Review Letters129,
200501
(2022).
G. Pelegrí, A. J. Daley, J. D. Pritchard,
High-fidelity multiqubit Rydberg gates via two-photon adiabatic rapid passage.
Quantum Science and Technology7,
045020
(2022).
We acknowledge funding from the following sources:
Open Positons
We are always keen to recruit highly motivated post-doctoral researchers and student’s. Current vacancies are listed below, however if you don’t see a vacancy for the research project you are interested in please contact jonathan.pritchard@strath.ac.uk for more details.
RF fields in the microwave and terahertz domain are ubiquitous for security and communications, however test equipment requires frequent recalibration and careful understanding of the perturbations caused by the antenna used for measurement. This project, a collaboration between researchers at the University of Strathclyde and Durham University, seeks to develop new all-optical field sensors operating in the microwave and terahertz domain using Rydberg atoms in a thermal vapour to act as microscopic antenna enabling metal-free probing, sub-wavelength imaging resolution and the ability to implement a traceable SI calibration offering superior sensitivity compared to existing technologies. Early results include a careful characterisation of linearity and optimal state choice for precision RF sensing using this approach.
