Extend universal mode-resolved relaxation beyond quasi-free systems

Determine whether a universal mode-resolved relaxation coefficient $c_{\rm relax}$ can be defined beyond the quasi-free setting, including systems with local dephasing in a free-fermion chain and interacting conformal field theories.

Background

The paper’s mode-resolved framework relies on quadratic Hamiltonians and linear Lindblad jump operators, which permit relaxation modes to be represented by effective single-particle rapidities. This structure enables continuous tracking of an individual Liouvillian mode as the conformal-interface transmission changes and leads to the universal dependence $c_{\rm relax}/c\approx1-\sqrt{1-t^2}$ in the models studied.

For more general dissipative processes, such as local dephasing, and for interacting conformal field theories, a single-particle description is generally unavailable. The authors therefore identify as unresolved whether an analogous many-body construction—tracking the same many-body Liouvillian mode across interface transmissions—retains a universal relaxation coefficient.