Robust implementation of quantum gates despite always-on exchange coupling in silicon double quantum dots

TL;DR

This paper presents a method for implementing robust quantum gates in silicon double quantum dots with always-on exchange coupling, overcoming limitations of the rotating wave approximation and charge noise.

Contribution

It introduces a pulse scheme that compensates for deviations from the rotating wave approximation and crosstalk, enabling high-fidelity quantum gates in challenging regimes.

Findings

Robust CZ and one-qubit gates achieved with smooth microwave pulsing.

Compensation of Bloch-Siegert-like shifts using local virtual gates.

Effective mitigation of charge noise and crosstalk in silicon quantum dots.

Abstract

Addressability of spin qubits in a silicon double quantum dot setup in the (1,1) charge configuration relies on having a large difference between the Zeeman splittings of the electrons. When the difference is not sufficiently large, the rotating wave approximation becomes inaccurate. We consider a device working in this regime, with always-on exchange coupling, and describe how a CZ gate and arbitrary one-qubit gates which are robust against charge noise can be implemented by smoothly pulsing the microwave source, while eliminating the crosstalk. We find that the most significant deviations from the rotating wave approximation, which are analogous to the Bloch-Siegert shift in a two-level system, can be compensated using local virtual gates.