Berlin 2024 – wissenschaftliches Programm
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QI: Fachverband Quanteninformation
QI 31: Decoherence and Open Quantum Systems
QI 31.5: Vortrag
Freitag, 22. März 2024, 10:30–10:45, HFT-FT 101
Minimising entanglement in tensor-network quantum trajectories — •Tatiana Vovk1,2 and Hannes Pichler1,2 — 1Institute for Quantum Optics and Quantum Information, Innsbruck, Austria — 2University of Innsbruck, Innsbruck, Austria
We introduce a way to directly leverage noise in trajectory-based stochastic methods to simulate open quantum many-body systems. Our key proposition revolves around the insight that the same system dynamics can be obtained by different stochastic propagators, which give distinct ensembles of pure-state trajectories. Specifically, we introduce an adaptive optimisation strategy for selecting the stochastic propagator with the objective of minimising the entanglement, which serves as a proxy of the expected cost of classically representing various trajectories. The physical mechanism underlying this idea is reminiscent of the phenomenon of measurement-induced phase transitions. We complement our discussion with explicit examples of one-dimensional open quantum dynamics, demonstrating that optimised trajectory-based methods employing matrix product states (MPSs) can yield an exponential reduction in classical computational cost compared to other MPS-trajectory-based methods or compared to conventional matrix product density operator technique. We note that our findings are interesting also from a fundamental quantum-information-theoretic perspective, since they give rise to heuristic algorithms for finding upper bounds on mixed-state entanglement measures, such as the entanglement of formation, a task that holds an independent and intrinsic interest.
Keywords: matrix product state; quantum trajectories; open quantum many-body systems; quantum entanglement; measurement-induced phase transition