Ballast charges for semiconductor spin qubits

TL;DR

This paper proposes ballast charges as a novel method to reduce charge noise in semiconductor spin qubits, significantly improving their coherence times by counteracting electromagnetic fluctuations.

Contribution

Introduction of ballast charges as a new technique to mitigate charge noise in semiconductor spin qubits, with simulation evidence of increased dephasing times.

Findings

Dephasing time increases by a factor of 4 to 6 with ballast charges.

Ballast charges effectively reduce the power spectral density of charge noise.

Simulation results support the potential of this method for improved qubit performance.

Abstract

Semiconductor spin qubits are an attractive platform for quantum computing, but their performance is degraded primarily by fluctuating electromagnetic environments. We introduce the concept of ballast charges, which are induced charges on the surface of an additional screening layer situated below the qubits. The counteractive behavior of these charges can significantly reduce the power spectral density associated with fluctuations from two-level systems that contribute to charge noise. Our simulations show that the dephasing time of a spin qubit in a Si/SiGe device increases by a factor of 4 to 6 on average when using this method. We also discuss the physical implementation and potential challenges of this approach.