Thesis
Laser phase noise in Rydberg atom arrays
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2026
- Thesis identifier
- T17672
- Person Identifier (Local)
- 202072458
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Laser noise is an unavoidable feature of modern quantum technologies, with lasers serving as a primary tool for manipulating and controlling quantum matter. Across all quantum architectures, fluctuations in the phase or amplitude of a laser drive can degrade performance: in digital platforms, they cause faulty quantum gates and qubit rotations, while in analogue platforms they disrupt coherent many-body dynamics. In this work, we use stochastic sampling to simulate laser phase noise based on experimentally relevant frequency power spectra. The main focus of the thesis will center around applying this realistic phase noise to simulations of analogue neutral-atom platforms based on Rydberg excitation. Despite such dephasing being a dominant source of decoherence in these systems, its effects in strongly interacting many-body regimes remain less well understood than in the single-qubit or few-qubit setting. In this context, we present a detailed theoretical study on the effects of experimentally realistic laser phase noise on adiabatic state preparation in a one-dimensional Rydberg spin chain. The core results are presented in two parts. First, we investigate the impact of phase noise on the fidelity of adiabatically preparing an antiferromagnetic ground state in the transverse-field Ising model (TFIM) with long-range Rydberg interactions. Using exact diagonalization and matrix product state (MPS) simulations, we reveal a competition between diabatic and dephasing excitations, leading to an optimal ramp time that balances these effects. In addition, we find that both these excitations to respect reflection symmetry, which confines dynamics to a reduced sector of the Hilbert space. Furthermore, by analyzing matrix elements between instantaneous eigenstates and performing phase noise evolution under time-independent Hamiltonians from different stages of the adiabatic protocol, we show that susceptibility to phase noise is strongly influenced by the system’s integrability. Second, we examine whether the states produced by noisy adiabatic preparation exhibit signatures of thermalization. Using the eigenstate thermalization hypothesis (ETH) as a framework, we compare long-time averages of observables to thermal predictions calculated using the Boltzmann distribution at the same energy. We choose to study system relevant observables in the interaction energy and long-range spin correlation; when phase noise is the dominant form of excitation we find that in the long-range TFIM both observables approach thermal values, whereas in a system with only nearest-neighbor interactions, deviations emerge in the case of interaction energy. We also test thermalization in the spin correlation observable as a function of system size, where we see consistent thermalization for small system sizes, but also observe a break down of this effect for the largest system sizes. Our analysis of these results highlights how interaction range, integrability breaking, and system size affect thermalization in noisy adiabatic quantum protocols. Overall, we provide tools to study laser phase noise in spin systems, and a quantitative understanding of how such noise affects the performance of adiabatic protocols in Rydberg arrays, as well as the mechanisms behind dephasing excitation. The tools and insights developed here are broadly applicable to diagnosing and mitigating noise effects in current and near-term neutral-atom experiments, and can be readily adapted to study both phase and amplitude noise from any experimental laser. As such this work contributes to the theoretical foundation for robust analogue quantum simulation.
- Advisor / supervisor
- Daley, Andrew
- Pritchard, Jonathan
- Resource Type
- DOI
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PDF of thesis T17672 | 2026-04-23 | Public | Download |