Prof. Beom Jun Kim (Sungkyunkwan University)
We study time-reversal dynamics of quantum diffusion in the Watts-Strogatz small-world networks at the rewiring probability $p$. We start from the localized wave packet, and integrate the time-dependent Schr\"odinger equation. At time $T$ a perturbation to the wave packet is made and then the system evolves backward in time until $t=2T$ is reached. We calculate the mean square displacement $\sigma(t; \eta)$ of the wave packet as a function of time $t$ at different perturbation strength $\eta$. The time irreversibility is quantitatively measured by $\sigma(2T; \eta) - \sigma(2T; 0)$, which reveals that the irreversibility linearly increases with $\eta$ in the weakly perturbed regime. The results from the WS networks and the regular network are compared.