Unraveling-Dependent Metastability in Monitored Quantum Systems and Associative Memories
Abstract
Metastability in open quantum systems is usually inferred from spectral separation in the Liouvillian, which governs unconditional, ensemble-averaged dynamics. We show that this diagnosis is incomplete at the level of individual quantum trajectories: conditioned realizations of the same unconditional dynamics can bypass, transiently access, or operationally preserve a metastable memory, depending on the monitored channel and the observed record. We demonstrate these mechanisms in a driven-dissipative nonlinear oscillator realizing a quantum associative memory, by comparing spectra, target fidelities, and phase-space distributions. The non-Hermitian dynamics obtained by post-selecting on the absence of detected events supports metastable retrieval, but with a distinct long-time fate: normalization selects the least-decaying mode of the non-Hermitian spectrum rather than the addressed memory branch. In contrast, stochastic jump trajectories can preserve retrieval over extended times when the post-measurement update remains compatible with the coherent memory structure. Thus trajectory-level metastability is not determined by the averaged generator alone; it requires compatibility between the monitored channel, the measurement record, and the metastable manifold.
Related
- Phase Transitions and Modulation in Dense Oscillatory Associative Memories
- Phases in a class of associative memories via hidden neurons
- Dense auto-hetero associative memories applied to noisy communication channels
- Factual recall in linear associative memories: sharp asymptotics and mechanistic insights
- Universal purification dynamics of monitored Clifford circuits
BibTeX
@misc{malakar2026unravelingdependent,
title = {{Unraveling-Dependent Metastability in Monitored Quantum Systems and Associative Memories}},
author = {Manali Malakar and Roberta Zambrini and Gian Luca Giorgi},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.06056},
eprint = {2609.06056},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.06056},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Unraveling-Dependent Metastability in Monitored Quantum Systems and Associative Memories
AU - Manali Malakar
AU - Roberta Zambrini
AU - Gian Luca Giorgi
PY - 2026
DA - 2026/09/05
PB - arXiv
DO - 10.48550/arxiv.2609.06056
UR - https://arxiv.org/abs/2609.06056
AB - Metastability in open quantum systems is usually inferred from spectral separation in the Liouvillian, which governs unconditional, ensemble-averaged dynamics. We show that this diagnosis is incomplete at the level of individual quantum trajectories: conditioned realizations of the same unconditional dynamics can bypass, transiently access, or operationally preserve a metastable memory, depending on the monitored channel and the observed record. We demonstrate these mechanisms in a driven-dissipative nonlinear oscillator realizing a quantum associative memory, by comparing spectra, target fidelities, and phase-space distributions. The non-Hermitian dynamics obtained by post-selecting on the absence of detected events supports metastable retrieval, but with a distinct long-time fate: normalization selects the least-decaying mode of the non-Hermitian spectrum rather than the addressed memory branch. In contrast, stochastic jump trajectories can preserve retrieval over extended times when the post-measurement update remains compatible with the coherent memory structure. Thus trajectory-level metastability is not determined by the averaged generator alone; it requires compatibility between the monitored channel, the measurement record, and the metastable manifold.
ER -