Spin Qubit Relaxation in a Moving Quantum Dot

TL;DR

This paper investigates how moving quantum dots cause spin qubit decoherence, revealing that electron motion induces relaxation with rates depending on material, and offers strategies to mitigate this decoherence.

Contribution

It provides a theoretical analysis of spin relaxation due to motion in quantum dots, highlighting the linear relationship with velocity and material-dependent relaxation times.

Findings

Spin relaxation rate is linear in dot velocity.

Relaxation times vary from sub microseconds in GaAs to over milliseconds in Si.

Motion-induced relaxation is a significant decoherence channel.

Abstract

Long-range quantum communication for spin qubits is an important open problem. Here we study decoherence of an electron spin qubit that is being transported in a moving quantum dot. We focus on spin decoherence due to spin-orbit interaction and a random electric potential. We find that at the lowest order, the motion induces longitudinal spin relaxation, with a rate linear in the dot velocity. Our calculated spin relaxation time ranges from sub $\mu$s in GaAs to above ms in Si, making this relaxation a significant decoherence channel. Our results also give clear indications on how to reduce the decoherence effect of electron motion.