Reduced sensitivity to charge noise in semiconductor spin qubits via symmetric operation

TL;DR

This paper presents a method to operate semiconductor spin qubits symmetrically between charge-state anti-crossings, significantly reducing charge noise sensitivity and enhancing qubit coherence and operation speed.

Contribution

The authors introduce a symmetric biasing technique that minimizes exchange energy sensitivity to charge noise while maintaining tunability, improving qubit performance.

Findings

Charge noise sensitivity reduced by over five times.

Increased number of observable exchange oscillations.

Performance improves with faster exchange rates.

Abstract

We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double-dot symmetrically between the charge-state anti-crossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We find that this method reduces the dephasing effect of charge noise by more than a factor of five in comparison to operation near a charge-state anti-crossing, increasing the number of observable exchange oscillations in our qubit by a similar factor. Performance also improves with exchange rate, favoring fast quantum operations.