Addressable electron spin resonance using donors and donor molecules in silicon

TL;DR

This paper demonstrates a method to selectively address silicon donor electron spins using hyperfine interactions, enabling scalable quantum computing architectures with precise qubit control.

Contribution

It introduces atomic-precision lithography to position donors and donor molecules in silicon, exploiting their hyperfine differences for qubit addressability.

Findings

Distinct hyperfine peaks enable selective qubit addressing.

Lithographic placement achieves ~16nm donor separation.

Simulations confirm large hyperfine interactions in 2P molecules.

Abstract

Phosphorus donor impurities in silicon are a promising candidate for solid-state quantum computing due to their exceptionally long coherence times and high fidelities. However, individual addressability of exchange coupled donor qubits with separations ~15nm is challenging. Here we show that by using atomic-precision lithography we can place a single P donor next to a 2P molecule 16(+/-1)nm apart and use their distinctive hyperfine coupling strengths to address qubits at vastly different resonance frequencies. In particular the single donor yields two hyperfine peaks separated by 97(+/-2.5)MHz, in contrast to the donor molecule which exhibits three peaks separated by 262(+/-10)MHz. Atomistic tight-binding simulations confirm the large hyperfine interaction strength in the 2P molecule with an inter-donor separation of ~0.7nm, consistent with lithographic STM images of the 2P site during device fabrication. We discuss the viability of using donor molecules for built-in addressability of electron spin qubits in silicon.