The Passivity Deformation Approach for the Thermodynamics of Isolated Quantum Setups

Abstract: Recently implemented quantum devices such as quantum processors and quantum simulators combine highly complicated quantum dynamics with high-resolution measurements. We present a passivity deformation methodology that sets thermodynamic constraints on the evolution of such quantum devices. This framework enhances the thermodynamic predictive power by simultaneously resolving four of the cardinal deficiencies of the second law in microscopic setups: i) It yields tight bounds even when the environment is microscopic; ii) The ultra-cold catastrophe is resolved; iii) It enables to integrate conservation laws into thermodynamic inequalities for making them tighter; iv) it bounds observables that are not energy-based, and therefore do not appear in the second law of thermodynamics. Furthermore, this framework provides insights to non-thermal environments, correlated environments, and to coarse-graining in microscopic setups. Our findings can be explored and used in physical setups such as trapped ions, superconducting circuits, neutral atoms in optical lattices and more.