Spin dynamics in InAs-nanowire quantum-dots coupled to a transmission line

TL;DR

This paper presents a theoretical study of electron spin manipulation in InAs nanowire quantum dots coupled to a transmission line resonator, enabling all-electrical quantum information processing and efficient spin coupling over distances.

Contribution

It introduces a novel all-electrical control scheme for spin qubits in nanowires and derives an effective entangling interaction for distant spins via the resonator mode.

Findings

Spin-orbit coupling enables electric manipulation of spins.

Phonon confinement reduces spin relaxation rates.

Efficient long-distance spin coupling via the resonator mode.

Abstract

We study theoretically electron spins in nanowire quantum dots placed inside a transmission line resonator. Because of the spin-orbit interaction, the spins couple to the electric component of the resonator electromagnetic field and enable coherent manipulation, storage, and read-out of quantum information in an all-electrical fashion. Coupling between distant quantum-dot spins, in one and the same or different nanowires, can be efficiently performed via the resonator mode either in real time or through virtual processes. For the latter case we derive an effective spin-entangling interaction and suggest means to turn it on and off. We consider both transverse and longitudinal types of nanowire quantum-dots and compare their manipulation timescales against the spin relaxation times. For this, we evaluate the rates for spin relaxation induced by the nanowire vibrations (phonons) and show that, as a result of phonon confinement in the nanowire, this rate is a strongly varying function of the spin operation frequency and thus can be drastically reduced compared to lateral quantum dots in GaAs. Our scheme is a step forward to the formation of hybrid structures where qubits of different nature can be integrated in a single device.