Characterizing Si:P quantum dot qubits with spin resonance techniques

TL;DR

This paper introduces a non-invasive ESR-based metrology method to characterize silicon phosphorus quantum dot qubits, revealing detailed information about donor count, electron, and nuclear spin configurations at atomic scale.

Contribution

It presents a novel ESR measurement technique combined with atomistic modeling to determine donor and electron configurations in silicon quantum dots.

Findings

ESR transition frequencies correlate with donor and electron positions.

The method enables atomic-scale characterization of donor quantum dots.

It provides a pathway for non-invasive qubit diagnostics.

Abstract

Quantum dots patterned by atomically precise placement of phosphorus donors in single crystal silicon have long spin lifetimes, advantages in addressability, large exchange tunability, and are readily available few-electron systems. To be utilized as quantum bits, it is important to non-invasively characterise these donor quantum dots post fabrication and extract the number of bound electron and nuclear spins as well as their locations. Here, we propose a metrology technique based on electron spin resonance (ESR) measurements with the on-chip circuitry already needed for qubit manipulation to obtain atomic scale information about donor quantum dots and their spin configurations. Using atomistic tight-binding technique and Hartree self-consistent field approximation, we show that the ESR transition frequencies are directly related to the number of donors, electrons, and their locations through the electron-nuclear hyperfine interaction.