Scalable simulation of nonequilibrium quantum dynamics via classically optimized unitary circuits

Causer, Luke; Jung, Felix; Mitra, Asimpunya; Pollmann, Frank; Gammon-Smith, Adam

Abstract

The advent of near-term digital quantum computers could offer us an exciting opportunity to investigate quantum many-body phenomena beyond that of classical computing. To make the best use of the hardware available, it is paramount that we have methods that accurately simulate Hamiltonian dynamics for limited circuit depths. In this paper, we propose a method to classically optimize unitary brickwall circuits to approximate quantum time evolution operators. Our method is scalable in system size through the use of tensor networks. We demonstrate that, for various three-body Hamiltonians, our approach produces quantum circuits that can outperform trotterization in both their accuracy and the quantum circuit depth needed to implement the dynamics, with the exact details being dependent on the Hamiltonian. We also explain how to choose an optimal time step that minimizes the combined errors of the quantum device and the brickwall circuit approximation.

Citation

Causer, L., Jung, F., Mitra, A., Pollmann, F., & Gammon-Smith, A. (2024). Scalable simulation of nonequilibrium quantum dynamics via classically optimized unitary circuits. Physical Review Research, 6(3), Article 033062. https://doi.org/10.1103/physrevresearch.6.033062

• Journal Article Type: Article
• Acceptance Date: Jun 18, 2024
• Online Publication Date: Jul 15, 2024
• Publication Date: 2024-07
• Deposit Date: Jul 22, 2024
• Publicly Available Date: Jul 23, 2024
• Journal: Physical Review Research
• Electronic ISSN: 2643-1564
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Issue: 3
• Article Number: 033062
• DOI: https://doi.org/10.1103/physrevresearch.6.033062
• Public URL: https://nottingham-repository.worktribe.com/output/37319043
• Publisher URL: https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.033062