Persistent Zitterbewegung of electron wave packet in time-dependent Rashba system

The Zitterbewegung (ZB) of an electron wave packet is theoretically studied in a Rashba spin-orbit coupling system, in the presence of the AC gate voltage modulation of the Rashba coupling strength. In the absence of AC modulation, the ZB dynamics of a wave packet rapidly decays due to interference from the different wave packet components. Under AC modulation of the ZB dynamics may be sustained indefinitely. We quantify two characteristics of this persistent ZB motion as a function of the modulation frequency ω, i.e., the peak amplitude (Amax)and the regularity RZ of the electron jitter motion. We analytically show that RZ improves with increasing ω. At sufficiently high modulation frequency, the ZB motion becomes totally regular, i.e., with a single characteristic frequency of 2ω. On the other hand, at high modulation frequency, the amplitude diminishes asymptotically as Amax ∝ 1/ω2. These trends of the ZB dynamics can also be obtained analytically by considering the spin-force picture. Our study provides the reference for achieving sustained large-amplitude and regular ZB oscillations under AC modulation, which is useful for experimental observation of the elusive ZB phenomenon in a Rasbha system.