Quantum rings with time dependent spin-orbit coupling: Rabi oscillations, spintronic Schrodinger-cat states, and conductance properties

Abstract

The strength of the (Rashba-type) spin-orbit coupling in mesoscopic semiconductor rings can be tuned with external gate voltages. Here we consider the case of a periodically changing spin-orbit interaction strength as induced by sinusoidal voltages. In a closed one dimensional quantum ring with weak spin-orbit coupling, Rabi oscillations are shown to appear. We find that the time evolution of initially localized wave packets exhibits a series of collapse and revival phenomena. Partial revivals -- that are typical in nonlinear systems -- are shown to correspond to superpositions of states localized at different spatial positions along the ring. These "spintronic Schrodinger-cat sates" appear periodically, and similarly to their counterparts in other physical systems, they are found to be sensitive to environment induced disturbances. The time dependent spin transport problem, when leads are attached to the ring, is also solved. We show that the "sideband currents" induced by the oscillating spin-orbit interaction strength can become the dominant output channel, even in the presence of moderate thermal fluctuations and random scattering events.

11 pages, 9 figures, submitted to PRB

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• Real-time dynamics of spin-dependent transport through a double-quantum-dot Aharonov-Bohm interferometer with spin-orbit interaction
• Characteristics of persistent spin current components in a quasi-periodic Fibonacci ring with spin-orbit interactions: Prediction of spin-orbit coupling and on-site energy
• Generation of spin-dependent coherent states in a quantum wire
• Implementation of Nano-scale Rectifiers: An Exact Study
• Quantum decoherence by magnetic fluctuations in a magnetic topological insulator
• Oscillating spin-orbit interaction as a source of spin-polarized wave packets in two-terminal nanoscale devices
• Tuning of few-electron states and optical absorption anisotropy in GaAs quantum rings