High-fidelity single-qubit gates of a strong driven singlet-triplet qubit

Abstract

Semiconductor quantum dot qubits are one of the most promising candidates for quantum computing. Among them, singlet-triplet qubits have attracted much attention due to their excellent properties of all-electric control and accurate readout. To improve qubitimmunity to charge noise, strong driving pulses are usually introduced to make operation as fast as possible. However, the complex dynamics induced by strong driving pulses make the rotational wave approximation inapplicable and hinder the implementation of high-fidelity qubit operation. In this work, we present a method utilizing simple quadrature pulses to correct errors of high-frequency oscillatory terms induced by strong driving. A scheme to obtain these pulses is proposed based on a full quantization of the system and Derivative Removal by Adiabatic Gate (DRAG) theory, as the former clarify the elementary processes of strong driving effects and enable the latter to find correction pulse shapes. The numerical stimulation results show that, with the help of the control pulses of this method, a NOT gate with 99.99% fidelity and gate time as low as 2 ns can be achieved, which indicates that the control error brought by strong driving is no longer a limiting factor. In particular, NOT gate fidelity higher than 99.9% is achievable even when the charge noise is in the level of 2 μeV. Notice that this method can be applied for any resonant-driving single-qubit rotation and not just NOT gates. Therefore, our approach will facilitate qubits to realize fast, high-fidelity single-qubit gates under charge noise.