In-flight distribution of an electron within a surface acoustic wave

TL;DR

This study experimentally investigates how to reliably confine and transport a single electron within a specific surface acoustic wave (SAW) minimum, crucial for quantum information applications involving flying electron qubits.

Contribution

It provides the first detailed experimental analysis of in-flight electron distribution within a SAW train and identifies device parameters for stable electron confinement.

Findings

Threshold acousto-electric amplitude for electron confinement identified

Transport robustness tested against stationary potential variations

Demonstrated controlled single-electron transport in a SAW platform

Abstract

Surface acoustic waves (SAW) have large potential to realize quantum-optics-like experiments with single flying electrons employing their spin or charge degree of freedom. For such quantum applications, highly efficient trapping of the electron in a specific moving quantum dot (QD) of a SAW train plays a key role. Probabilistic transport over multiple moving minima would cause uncertainty in synchronisation that is detrimental for coherence of entangled flying electrons and in-flight quantum operations. It is thus of central importance to identify the device parameters enabling electron transport within a single SAW minimum. A detailed experimental investigation of this aspect is so far missing. Here we fill this gap by demonstrating time-of-flight measurements for a single electron that is transported via a SAW train between distant stationary QDs. Our measurements reveal the in-flight distribution of the electron within the moving acousto-electric quantum dots of the SAW train. Increasing the acousto-electric amplitude, we observe the threshold necessary to confine the flying electron at a specific, deliberately chosen SAW minimum. Investigating the effect of a barrier along the transport channel, we also benchmark the robustness of SAW-driven electron transport against stationary potential variations. Our results pave the way for highly controlled transport of electron qubits in a SAW-driven platform for quantum experiments.