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arXiv · 2602.00891

Universal Quantum Birthmark: Ghost of the quantum past

Ivy Xiaoya·Anton M. Graf·Eric J. Heller·Joonas Keski-Rahkonen
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Abstract

Quantum dynamics retains a permanent and universal memory of its initial conditions, even in systems whose spectra display fully chaotic, random-matrix behavior. This effect, known as the quantum birthmark, appears as an enhancement of the long-time return probability of any non-stationary state compared to the overlap with a typical ergodic state. In this work, we develop the full theoretical foundation for this universal contribution that depends only on the global symmetry class and accessible Hilbert-space dimension, not on the microscopic dynamics. Our findings reveal that quantum evolution preserves an unavoidable, symmetry-controlled imprint of its origin, a quantum effect calling into question classical expectations of ergodicity and the resulting thermalization scenarios.

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Ivy Xiaoya, Anton M. Graf, Eric J. Heller, Joonas Keski-Rahkonen. 2026-01-31. Universal Quantum Birthmark: Ghost of the quantum past. https://arxiv.org/abs/2602.00891

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