Unified Gorini-Kossakowski-Lindblad-Sudarshan quantum master equation beyond the secular approximation

Derivation of a quantum master equation for a system weakly coupled to a bath which takes into account nonsecular effects, but nevertheless has the mathematically correct Gorini-Kossakowski-Lindblad-Sudarshan form (in particular, it preserves positivity of the density operator) and also satisfies the standard thermodynamic properties is a known long-standing problem in theory of open quantum systems. The nonsecular terms are important when some energy levels of the system or their differences (Bohr frequencies) are nearly degenerate. We provide a fully rigorous derivation of such equation based on a formalization of the weak-coupling limit for the general case.

Automated summary

The study addresses a long-standing problem in the theory of open quantum systems by providing a fully rigorous derivation of a quantum master equation that takes into account nonsecular effects while maintaining mathematical correctness and thermodynamic properties. The nonsecular terms are essential when energy levels of the system are nearly degenerate, and the derivation is based on a formalization of the weak-coupling limit for the general case.