Voltage Control of Exchange Coupling in Phosphorus Doped Silicon

TL;DR

This paper investigates how applying voltage biases to surface electrodes in phosphorus-doped silicon can modulate the exchange interaction between donor electrons, which is crucial for quantum computing applications.

Contribution

It demonstrates the ability to control the exchange interaction strength via electro-static fields, providing a method for tunable quantum gate operations.

Findings

Voltage biases can enhance or reduce exchange interaction

Control depends on bias magnitude and donor separation orientation

Potential for precise quantum gate control in silicon-based qubits

Abstract

Motivated by applications to quantum computer architectures we study the change in the exchange interaction between neighbouring phosphorus donor electrons in silicon due to the application of voltage biases to surface control electrodes. These voltage biases create electro-static fields within the crystal substrate, perturbing the states of the donor electrons and thus altering the strength of the exchange interaction between them. We find that control gates of this kind can be used to either enhance, or reduce the strength of the interaction, by an amount that depends both on the magnitude and orientation of the donor separation.