Many-Body Anti-Zeno Thermalization and Zeno Determinism in Monitored Hamiltonian Dynamics
Phys. Rev. Lett. 136, 080602 – Published 23 February, 2026
DOI: https://doi.org/10.1103/py19-84k9
Abstract
Random quantum states are essential for quantum information science, with applications ranging from quantum computing to cryptography. Prior approaches for generating these states often rely on using a large bath to thermalize a smaller system, with a subsequent measurement on the bath used to postselect a random state. To reduce the required size of the bath, we propose a resource-efficient scheme using holographic deep thermalization driven by Hamiltonian evolution, combined with midcircuit measurements. This scheme relies on dynamical circuits, enabling a trade-off between spatial and temporal resources and allowing the generation of genuinely random states with only a constant-size bath. We quantify the randomness using the frame potential and derive its asymptotic behavior, which shows good agreement with our numerical simulations and IBM Quantum Platform results. For a fixed total evolution time, increasing the number of midcircuit measurements initially produces an exponential decrease in the frame potential—a quantum anti-Zeno behavior arising from holographic deep thermalization. Past a critical number of midcircuit measurements, the frame potential rises again, signaling the onset of the quantum Zeno effect.
