Előadó: İskender Yalçınkaya (Czech Technical University in Prague (host: Kiss Tamás))

Előadás címe: Disorder-free localization in quantum walks

Dátum: Tuesday, 25 January 2022, 10:00

Helyszín: Bldg. 1, auditorium, https://wigner-hu.zoom.us/j/95461797924?pwd=RDBKcWpoelpadUhoRzhNUnRKai9… Meeting ID: 954 6179 7924 Passcode: 956543

The phenomenon of localization usually happens due to the existence of disorder in a medium. Nevertheless, certain quantum systems allow dynamical localization solely due to the nature of internal interactions. We study a discrete-time quantum walker which exhibits disorder-free localization. The quantum walker moves on a one-dimensional lattice and interacts with on-site spins by coherently rotating them around a given axis at each step. Since the spins do not have dynamics of their own, the system poses the local spin components along the rotation axis as an extensive number of conserved moments. When the interaction is weak, the spread of the walker shows subdiffusive behaviour having downscaled ballistic tails in the evolving probability distribution at intermediate time scales. However, as the interaction gets stronger the walker gets exponentially localized in the complete absence of disorder in both lattice and initial state. We investigate the relaxation and entanglement dynamics of the on-site spins due to their coupling with the quantum walker. Surprisingly, we find that even in the delocalized regime, entanglement growth and relaxation occur slowly unlike majority of the other models displaying a localization transition.