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QI: Fachverband Quanteninformation

QI 17: Decoherence and Open Systems II

QI 17.8: Vortrag

Donnerstag, 12. März 2026, 17:15–17:30, BEY/0137

Conserved quantities enable the quantum Mpemba effect in weakly open systems — •Iris Ulcakar^{1, 2}, Gianluca Lagnese¹, Rustem Sharipov², and Zala Lenarcic¹ — ¹"Jozef Stefan" Institute, Ljubljana, Slovenia — ²Faculty of Mathematics and Physics, University of Ljubljana, Slovenia

Observation of the quantum Mpemba effect has spurred much interest in its enabling conditions and its relation to the classical counterpart. Here, we consider weakly open many-body quantum systems initialized in different thermal states and examine when the initially farther state relaxes to the (non-equilibrium) steady state faster. We claim that the number of conserved quantities in the unitary part plays a crucial role: the Mpemba effect is possible only when the Hamiltonian commutes with other extensive operators or is integrable. The reason lies in the dynamical evolution happening in spaces of different dimensions. When energy is the only approximately conserved quantity, dissipation pushes the dynamics within a single-parameter manifold of different thermal states. In contrast, for Hamiltonians with several conserved quantities, the dynamics drift in the multi-dimensional space of generalized Gibbs ensembles, whose distance to the steady state is less trivial. We provide numerical results for large system sizes using tensor networks and free-fermion techniques, thereby supporting our claim.

Keywords: Mpemba effect; open quantum systems; dissipation; generalized Gibss ensemble; nonequilibrium dynamics