A hotter quantum system may relax faster, simulations suggest

Researchers at the Jožef Stefan Institute and University of Ljubljana have discovered a key condition for the quantum Mpemba effect, the counter-intuitive phenomenon where a hotter system cools faster than a colder one. The work demonstrates the effect is only possible when a system’s Hamiltonian commutes with other operators, essentially meaning it is integrable. This finding links the effect to the mathematical properties of the system itself, not just initial temperature, and challenges conventional thermodynamic intuition. The team used tensor networks and free-fermion techniques to model large system sizes, supporting their claim that multiple conserved quantities allow dynamics to evolve in a multi-dimensional space, enabling faster relaxation. The possibility of a hotter quantum system relaxing to a steady state faster than a colder one depends on the presence of multiple conserved quantities within the system, according to new simulations. Unlike systems where energy is the sole conserved property, those with additional conserved quantities evolve within a…