# Symmetric Operation of the Resonant Exchange Qubit

## TL;DR

This study demonstrates symmetric operation of a resonant exchange qubit in a triple-dot system, revealing insights into noise effects and coherence enhancement techniques, with implications for quantum computing scalability.

## Contribution

It introduces a symmetric triple-dot configuration for resonant exchange qubits and analyzes noise impacts and coherence improvements using dynamical decoupling.

## Key findings

- Operating at the sweet spot reduces sensitivity to control voltages.
- Dynamical decoupling extends qubit coherence times.
- Voltage noise and Overhauser fluctuations influence Rabi decay.

## Abstract

We operate a resonant exchange qubit in a highly symmetric triple-dot configuration using IQ-modulated RF pulses. At the resulting three-dimensional sweet spot the qubit splitting is an order of magnitude less sensitive to all relevant control voltages, compared to the conventional operating point, but we observe no significant improvement in the quality of Rabi oscillations. For weak driving this is consistent with Overhauser field fluctuations modulating the qubit splitting. For strong driving we infer that effective voltage noise modulates the coupling strength between RF drive and the qubit, thereby quickening Rabi decay. Application of CPMG dynamical decoupling sequences consisting of up to n = 32 {\pi} pulses significantly prolongs qubit coherence, leading to marginally longer dephasing times in the symmetric configuration. This is consistent with dynamical decoupling from low frequency noise, but quantitatively cannot be explained by effective gate voltage noise and Overhauser field fluctuations alone. Our results inform recent strategies for the utilization of partial sweet spots in the operation and long-distance coupling of triple-dot qubits.