Transparently manipulating spin–orbit qubit via exact degenerate ground states**Project supported bythe National Natural Science Foundation of China (Grant Nos. 11204077 and 11475060), the Natural Science Foundation of Hunan Province, China (Grant No. 2019JJ10002), the Hunan Provincial Hundred People Plan, China (2019), and the Science and Technology Plan Project of Hunan Province, China.

Abstract

By investigating a harmonically confined and periodically driven particle system with spin–orbit coupling (SOC) and a specific controlled parameter, we demonstrate an exactly solvable two-level model with a complete set of spin-motion entangled Schrödinger kitten (or cat) states. In the undriven case, application of a modulation resonance results in the exact stationary states. We show a decoherence-averse effect of SOC and implement a transparent coherent control by exchanging positions of the probability-density wavepackets to create transitions between the different degenerate ground states. The expected energy consisting of quantum and continuous parts is derived, and the energy deviations caused by the exchange operations are much less than the quantum gap. The results could be directly extended to a weakly coupled single-particle chain for transparently encoding spin–orbit qubits via the robust spin-motion entangled degenerate ground states.