Transitions in the learnability of global charges from local measurements
Quantum Physics
2022-11-11 v3 Disordered Systems and Neural Networks
Statistical Mechanics
Strongly Correlated Electrons
Abstract
We consider monitored quantum systems with a global conserved charge, and ask how efficiently an observer ("eavesdropper") can learn the global charge of such systems from local projective measurements. We find phase transitions as a function of the measurement rate, depending on how much information about the quantum dynamics the eavesdropper has access to. For random unitary circuits with U(1) symmetry, we present an optimal classical classifier to reconstruct the global charge from local measurement outcomes only. We demonstrate the existence of phase transitions in the performance of this classifier in the thermodynamic limit. We also study numerically improved classifiers by including some knowledge about the unitary gates pattern.
Keywords
Cite
@article{arxiv.2206.12429,
title = {Transitions in the learnability of global charges from local measurements},
author = {Fergus Barratt and Utkarsh Agrawal and Andrew C. Potter and Sarang Gopalakrishnan and Romain Vasseur},
journal= {arXiv preprint arXiv:2206.12429},
year = {2022}
}