Noncommuting conserved quantities in quantum thermodynamics can increase entanglement

Shayan Majidy

PhD student at the Institute for Quantum Computing, University of Waterloo. Advisor: Raymond Laflamme
Wednesday, February 22, 2023 at 12:00pm
Evans Hall Room 560 and via Zoom (see below to obtain Zoom link)

Across thermodynamics, systems exchange quantities that are conserved globally, such as energy, particles, and electric charges. These quantities are represented by Hermitian operators, which have traditionally been assumed to commute with each other. However, noncommutation is a key feature of quantum theory. A major challenge in studying how charges’ noncommutation influences thermodynamic phenomena is isolating the effects of charges’ noncommutation from spurious factors, e.g., the effects of conserving multiple charges. To address this challenge, we construct two multiqubit models that parallel each other closely, except one model’s charges do not commute. The noncommuting-charge model exhibits greater average entanglement. We quantify the increase with the Page curve, often used to measure a closed quantum many-body system’s internal thermalization. We confirm this result both analytically and numerically. Since entanglement is a key feature of quantum many-body thermalization, our findings provide a new perspective on how charges’ noncommutation can impact thermalization.

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