Quantum diffusion in the Harper model under polychromatic time-perturbation.

Yamada, Hiroaki S; Ikeda, Kensuke S · Phys Rev E · 2026

basic_science · Level V

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Abstract

Quantum dynamics of the Harper model with self-duality exhibits localized, diffusive, and ballistic states depending on the potential strength V. By adding time-dependent harmonic perturbations composed of M incommensurate frequencies, we show that all states of the Harper model transition to quantum diffusive states as the perturbation strength ε increases for M≥3. The transition schemes and diffusion behaviors are discussed in detail and the phase diagram in the (ε,V) parameter space is presented.