The remarkable prospect for quantum-dot-coupled tin qubits in silicon

TL;DR

This paper proposes using spin-119Sn nuclei in silicon as robust qubits with strong hyperfine interactions, enabling resilient quantum gates and universal quantum computation through electron shuttling and magnetic resonance techniques.

Contribution

It predicts a significantly enhanced hyperfine interaction in tin-doped silicon and introduces a hyperfine-induced electro-nuclear controlled-phase gate for quantum computing.

Findings

Hyperfine interaction in tin-doped silicon is about ten times larger than in silicon-29.

The proposed gate operation is highly resilient to charge and voltage noise.

Spin flips are suppressed with modest magnetic fields, and nuclear spin bath noise can be mitigated.

Abstract

Spin-$\frac{1}{2}$ $^{119}$Sn nuclei in a silicon semiconductor could make excellent qubits. Nuclear spins in silicon are known to have long coherence times. Tin is isoelectronic with silicon, so we expect electrons can easily shuttle from one Sn atom to another to propagate quantum information via a hyperfine interaction that we predict, from all-electron linearized augmented plane wave density functional theory calculations, to be roughly ten times larger than intrinsic $^{29}$Si. A hyperfine-induced electro-nuclear controlled-phase (e-n-CPhase) gate operation, generated (up to local rotations) by merely holding an electron at a sweet-spot of maximum hyperfine strength for a specific duration of time, is predicted to be exceptionally resilient to charge/voltage noise. Diabatic spin flips are suppressed with a modest magnetic field ($>15~$mT for $<10^{-6}$ flip probabilities) and nuclear spin bath noise may be avoided via isotopic enrichment or mitigated using dynamical decoupling or through monitoring and compensation. Combined with magnetic resonance control, this operation enables universal quantum computation.