Two-spin relaxation of P-dimers in Silicon

TL;DR

This paper investigates the relaxation mechanisms of two-electron spin states in phosphorus dimers in silicon, highlighting how hyperfine and electron-phonon interactions influence relaxation times relevant for quantum computing.

Contribution

It provides a theoretical calculation of triplet relaxation rates in P-dimers using Heitler-London and effective mass approximations, linking relaxation to ESR signals and quantum gate operation times.

Findings

Triplet relaxation rates depend on magnetic field and hyperfine interactions.

Relaxation times set upper bounds for quantum gate pulse durations.

The study offers insights into decoherence mechanisms in donor-based silicon qubits.

Abstract

We study two-electron singlet-triplet relaxation of donor-bound electrons in Silicon. Hyperfine interaction of the electrons with the phosphorus (P) nuclei, in combination with the electron-phonon interaction, lead to relaxation of the triplet states. Within the Heitler-London and effective mass approximations, we calculate the triplet relaxation rates in the presence of an applied magnetic field. This relaxation mechanism affects the resonance peaks in current Electron Spin Resonance (ESR) experiments on P-dimers. Moreover, the estimated time scales for the spin decay put an upper bound on the gate pulses needed to perform fault-tolerant two-qubit operations in donor-spin-based quantum computers (QCs).