Spin Diffusion and Relaxation in Solid State Spin Quantum Computer

TL;DR

This paper investigates spin diffusion and relaxation in solid state spin quantum computers, showing how external magnetic fields can suppress relaxation and analyzing different relaxation mechanisms through theoretical and numerical methods.

Contribution

It introduces a detailed analysis of spin relaxation processes in two quantum computer models and demonstrates how external magnetic fields can mitigate these effects.

Findings

External non-uniform magnetic fields suppress spin relaxation.

Different relaxation processes include magnetic moment excitation and domain wall formation.

Optimal parameters for relaxation suppression are identified.

Abstract

The processes of spin diffusion and relaxation are studied theoretically and numerically for quantum computation applications. Two possible realizations of a spin quantum computer (SQC) are analyzed: (i) a boundary spin chain in a 2D spin array and (ii) an isolated spin chain. In both cases, spin diffusion and relaxation are caused by a fast relaxing spin located outside the SQC. We have shown that in both cases the relaxation can be suppressed by an external non-uniform magnetic field. In the second case, our computer simulations have revealed various types of relaxation processes including the excitation of a random distribution of magnetic moments and the formation of stationary and moving domain walls. The region of optimal parameters for suppression of rapid spin relaxation is discussed.