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Certifying steady-state properties of open quantum systems

Luke Mortimer1,*, Donato Farina2, Grazia Di Bello2, David Jansen1, Andreas Leitherer1, Pere Mujal1, and Antonio Acín1,3

  • *Contact author: lbmortimer1998@gmail.com

Phys. Rev. Research 7, 033237 – Published 10 September, 2025

DOI: https://doi.org/10.1103/hbrt-cn8q

Abstract

Estimating the steady-state properties of open many-body quantum systems is a fundamental challenge in quantum science and technologies. In this work, we present a scalable approach based on semidefinite programming to derive certified bounds on the expectation value of an arbitrary observable in the steady state of Lindbladian dynamics. We illustrate our method on a series of many-body systems, including paradigmatic spin-1/2 chains and two-dimensional ladders, considering both equilibrium and nonequilibrium steady states. We benchmark our method with state-of-the-art tensor-network approaches that, unlike our method, are only able to provide estimates, with no guarantee, on steady-state quantities. For the tested models, only modest computational effort is needed to obtain certified nontrivial bounds for system sizes intractable by exact methods. Our method introduces the first general numerical tool for bounding steady-state properties of open quantum dynamics, opening an avenue in the understanding of stable configurations in many-body systems.

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