Quantum Information Journal Club: “Quantum information transitions and the breakdown of non-Abelian topological quantum memories”

Speaker: Pablo Sala (ift)

Title: “Quantum information transitions and the breakdown of non-Abelian topological quantum memories”

Venue&Time: Gray Room 3 / 11:30

Abstract: How much noise can a system tolerate before encoded quantum information becomes irrecoverable? This question connects quantum error correction to the stability of quantum matter. In this talk, I will explore the transition between a recoverable and an irrecoverable phase when a quantum many-body system is subject to symmetry-preserving noise. For Abelian symmetries, this reconstruction becomes essentially classical: local syndrome data captures the relevant information and maps to familiar statistical-mechanics decoding problems. For non-Abelian symmetries, the situation is qualitatively different. The noisy state retains hidden fusion information that cannot be read from local syndromes alone. This leads naturally to a hierarchy of measurement protocols, where increasingly nonlocal measurements reveal progressively more of the fusion structure. I will describe how this perspective gives a framework for comparing reconstruction thresholds and developing error correction protocols for the closely related problem of non-Abelian topological quantum memories.