Transparently manipulating spin–orbit qubit via exact degenerate ground states*

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.

Electrical manipulation of a hole ‘spin’–orbit qubit in nanowire quantum dot: The nontrivial magnetic field effects

“…[33] Note that this strong spin-orbit coupled 1D dispersion has many applications in the studies of the spin-orbit qubit [34][35][36][37][38][39] and the Bose gases. [40][41][42][43][44] Inspired by recent advances in manipulating electrically the hole spin in a Ge nanowire quantum dot, [26,[45][46][47][48] here we address the spinorbit coupling physics in a Ge nanowire.…”

Customizing topological phases in the twisted bilayer superconductors with even-parity pairings

“…In this paper, we propose two approaches to realize this: Rashba and Dresselhaus mixed SOC and anisotropic nearest neighbor hopping with t x = t y . [21,30] As long as one of them is present in the system, it is possible to achieve any form of encirclement of FS into a removable DPN and induce a topological phase transition by adjusting the chemical potential (which controls the size of FS) or the twist angle (which controls the orientation of FS).…”

Exact solutions for a spin-orbit coupled ultracold atom held in a driven double well

“…Although widely studied over the past few decades, up to now many accurate solutions are obtained, which are based on two-level (or two-state) systems [1][2][3][4][5][6][7][8][9][10][11][12][13], such as the paradigmatic Landau-Zener [3,4] and Rabi [6] models, driven two-level systems [1,11], complete population inversion by a phase jump for a two-state system [12], the Jaynes-Cummings model [13], and so on. The accurate analytic solution has proved to be very important in the contexts of qubit control [14][15][16] and has been extended to a series of precise controls [2,[8][9][10][11][12][17][18][19]. Not only that, the accurate solutions are extremely useful for the fundamental importance of quantum systems.…”

“…To our knowledge, many works related to the quantum dynamics of SO-coupled cold atomic systems have been studied by applying approximate methods [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], for instance, numerical simulation [45][46][47][48][49][50], variational approximation [45,48,51], mean-field theory and random phase approximation [52][53][54], high-frequency approximation(or rotating-wave approximation) [43,44,55,[58][59][60][61][62][63], multiple-time-scale asymptotic analysis [56,57], etc. However, the research on quantum spin dynamics of SO-coupled ultracold atomic systems based on exact solutions is still extremely rare [16].…”