4 Apr 2024 | Mattia Moroder, Oisín Culhane, Krissia Zawadzki, and John Goold
The paper investigates the quantum Mpemba effect from the perspective of non-equilibrium quantum thermodynamics, focusing on Davies maps. The authors demonstrate that an exponential speedup to equilibrium always occurs when a state with coherences in the energy eigenbasis is transformed to a diagonal state, provided the spectral gap of the generator is defined by a complex eigenvalue. They argue that this transformation yields a genuine quantum Mpemba effect, characterized by a higher non-equilibrium free energy. The study uses both single-qubit and multi-qubit examples to illustrate the dynamics of non-equilibrium free energy and irreversible entropy production. The key findings include the construction of a unitary transformation that increases the non-equilibrium free energy and eliminates overlaps with slow-decaying modes, leading to exponential thermalization. The work highlights the importance of the non-equilibrium free energy in defining and studying the quantum Mpemba effect and suggests potential applications in dissipative state engineering protocols.The paper investigates the quantum Mpemba effect from the perspective of non-equilibrium quantum thermodynamics, focusing on Davies maps. The authors demonstrate that an exponential speedup to equilibrium always occurs when a state with coherences in the energy eigenbasis is transformed to a diagonal state, provided the spectral gap of the generator is defined by a complex eigenvalue. They argue that this transformation yields a genuine quantum Mpemba effect, characterized by a higher non-equilibrium free energy. The study uses both single-qubit and multi-qubit examples to illustrate the dynamics of non-equilibrium free energy and irreversible entropy production. The key findings include the construction of a unitary transformation that increases the non-equilibrium free energy and eliminates overlaps with slow-decaying modes, leading to exponential thermalization. The work highlights the importance of the non-equilibrium free energy in defining and studying the quantum Mpemba effect and suggests potential applications in dissipative state engineering protocols.