Quantum asymmetry can grow faster in broken systems

Researchers have generalized a measure of symmetry breaking, entanglement asymmetry, to account for quantum systems fracturing into exponentially many disconnected sectors. Lorenzo Gotta of the University of Geneva, Filiberto Ares of SISSA and INFN and Sara Murciano of Université Paris-Saclay demonstrate that while asymmetry typically has an upper bound, it can scale extensively in these fragmented systems. This distinction allows researchers to differentiate between “classical” and “quantum” fragmentation, a key insight into the behavior of complex quantum states. The work qualitatively reproduces recent findings on asymmetry dynamics in random quantum circuits, suggesting a universal behavior for these U(1) charges in local ergodic systems. Entanglement asymmetry, a quantitative measure of symmetry breaking in quantum states, typically…