Nonreciprocal Relaxation Acceleration

Driven by recent discoveries regarding the quantum Mpemba effect, the anomalous relaxation dynamics of open quantum systems have garnered significant attention. While expediting thermalization to equilibrium has been extensively studied, dynamically accelerating the convergence toward nonequilibrium steady states remains a formidable challenge. In this letter, we find that a transiently engineered nonreciprocal dissipative channel can provide a shortcut that accelerates relaxation to the target reciprocal nonequilibrium steady state. Using a two-mode interacting bosonic model, we demonstrate that the temporal activation of a nonreciprocal channel effciently suppresses prolonged inter-mode energy oscillations, enforcing a rapid, unidirectional thermal dump into the environment. Counterintuitively, under symmetric local dissipation, both nonreciprocal directions exhibit relaxation speedup with identical asymptotic spectral decay rates. Our results establish a route to accelerated nonequilibrium steady-state preparation in the studied bosonic model, with a covariance-based suffcient condition that extends to a multimode chain.