The Resonant Exchange Qubit

TL;DR

This paper presents a solid-state qubit leveraging exchange interactions for rapid, full control with high coherence, demonstrating fast gate operations and suppression of hyperfine-induced leakage.

Contribution

It introduces a resonant exchange qubit design that enables fast, two-axis control at a sweet-spot, with detailed experimental and theoretical validation.

Findings

π/2-gate time of 2.5 ns

Coherence time of 19 μs with echo

Excellent agreement between model and experiment

Abstract

We introduce a solid-state qubit in which exchange interactions among confined electrons provide both the static longitudinal field and the oscillatory transverse field, allowing rapid and full qubit control via rf gate-voltage pulses. We demonstrate two-axis control at a detuning sweet-spot, where leakage due to hyperfine coupling is suppressed by the large exchange gap. A {\pi}/2-gate time of 2.5 ns and a coherence time of 19 {\mu}s, using multi-pulse echo, are also demonstrated. Model calculations that include effects of hyperfine noise are in excellent quantitative agreement with experiment.