Relaxation Effects

V. M. Akulin, N. V. Karlov

Yoichi Taira, Tatsuo Yajima

A detailed theoretical analysis is given for the ultrafast relaxation study using polarization spectroscopy in the frequency domain to clarify the effect of cross relaxation on the measured results. It is shown that the calculated nonlinear spectral response function reflects the inhomogeneous width rather than the homogeneous one if the rate of cross relaxation of the transition becomes so singnificant. This prevents us from precise determination of phase relaxation Time T 2 of the transition by the stationary polarization spectroscopy. It is further shown that the cross relaxation effect onto the measured spectral response function can effectively be diminished by introducing a partially transient condition. An experiment using picosecond light pulses is presented to demonstrate this fact.

I-Hsi Chen, Po-Shuo Huang, Shang-Yu Wu

We reconstruct the information quantities in the holographic relaxed superconductor system and discuss how these quantities behave under non-symmetry configuration. We then combine the effect of the superconductor and the momentum relaxation, and find out that the superconductor effect will change how the momentum relaxation affect these information quantities.

Bassano Vacchini

Marc Cheneau

Stefano Longhi

We unveil a quantum Pontus-Mpemba effect enabled by the Liouvillian skin effect in a dissipative tight-binding chain with asymmetric incoherent hopping and coherent boundary coupling. The skin effect, induced by non-reciprocal dissipation, localizes relaxation modes near the system boundaries and gives rise to non-orthogonal spectral geometry. While such non-normality is often linked to slow relaxation, we show that it can instead accelerate relaxation through a two-step protocol - realizing a quantum Pontus-Mpemba effect. Specifically, we consider a one-dimensional open chain with coherent hopping $J$, asymmetric incoherent hoppings $J_{\rm R} \neq J_{\rm L}$, and a controllable end-to-end coupling $ε$. For $ε=0$, the system exhibits the Liouvillian skin effect, with left and right eigenmodes localized at opposite edges. We compare two relaxation protocols toward the same stationary state: (i) a direct relaxation with $ε=0$, and (ii) a two-step (Pontus) protocol where a brief coherent evolution transfers the excitation across the lattice before relaxation. Although both share the same asymptotic decay rate, the two-step protocol relaxes significantly faster due to its reduced overlap with the slow boundary-localized Liouvillian mode. The effect disappears when $J_{\rm R}=J_{\rm L}$, i.e., when the skin effect vanishes. Our results reveal a clear connection between boundary-induced non-normality and protocol-dependent relaxation acceleration, suggesting new routes for controlling dissipation and transient dynamics in open quantum systems.