The asymmetric resonant exchange qubit under the influence of electrical noise

TL;DR

This paper analyzes how electrical charge noise affects an asymmetric resonant exchange (RX) qubit in triple quantum dots, identifying optimal operating points ('sweet spots') that minimize noise impact for improved qubit stability.

Contribution

It introduces a detailed noise model for the RX qubit, finds the existence and location of sweet spots in parameter space, and proposes a new favorable operating regime under weak charge noise.

Findings

Sweet spots exist within low bias regime.

Location of sweet spots depends on hopping strength and asymmetry.

A new operating regime is identified for weak charge noise.

Abstract

We investigate the influence of electrical charge noise on a resonant exchange (RX) qubit in a triple quantum dot. This RX qubit is a variation of the exchange-only spin qubit which responds to a narrow-band resonant frequency. Our noise model includes uncorrelated charge noise in each quantum dot giving rise to two independent (noisy) bias parameters $\varepsilon$ and $\Delta$. We calculate the energy splitting of the two qubit states as a function of these two bias detuning parameters to find "sweet spots", where the qubit is least susceptible to noise. Our investigation shows that such sweet spots exist within the low bias regime, in which the bias detuning parameters have the same magnitude as the hopping parameters. The location of the sweet spots in the $(\varepsilon,\Delta)$ plane depends on the hopping strength and asymmetry between the quantum dots. In the regime of weak charge noise, we identify a new favorable operating regime for the RX qubit based on these sweet spots.