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Scaling Laws of Quantum Information Lifetime in Monitored Quantum Dynamics
Publication Year
2025
Type
Journal Article
Abstract
Quantum information is typically fragile under measurement and environmental coupling. Remarkably,
we find that its lifetime can scale exponentially with system size when the environment is
continuously monitored via mid-circuit measurements – regardless of bath size. Starting from a maximally
entangled state with a reference, we analytically prove this exponential scaling for typical Haar
random unitaries and confirm it through numerical simulations in both Haar-random and chaotic
Hamiltonian systems. In the absence of bath monitoring, the lifetime exhibits a markedly different
scaling: it grows at most linearly – or remains constant – with system size and decays inversely with
bath size. We further extend our findings numerically to a broad class of initial states. We discuss
implications for monitored quantum circuits in the weak measurement limit, quantum algorithms
such as quantum diffusion models and quantum reservoir computing, and quantum communication.
Finally, we evaluate the feasibility of resolving the predicted scaling regimes experimentally via noisy
simulations of IBM Quantum hardwares.
Journal
arxiv
Date Published
06/2025