Latched readout for the quantum dot hybrid qubit

TL;DR

This paper introduces a latched readout method for quantum dot hybrid qubits that significantly extends the readout window by stabilizing the excited state in a metastable charge configuration, improving single-shot readout reliability.

Contribution

The authors demonstrate a novel latched readout technique that leverages metastable charge states, enabling longer and more tunable readout windows for quantum dot hybrid qubits.

Findings

Readout window extended to 2.5 ms using metastable charge states.

Working in (4,1)-(3,2) charge configuration enhances tunability.

Readout size determined by orbital splitting, not valley splitting.

Abstract

A primary method of reading out a quantum dot hybrid qubit involves projection of the logical basis onto distinct charge states that are readily detected by an integrated charge sensing dot. However, in the simplest configuration, the excited charge state decays rapidly, making single-shot readout challenging. Here, we demonstrate a readout procedure where the qubit excited state is latched to a metastable charge configuration whose lifetime is tunnel rate limited, persisting here as long as 2.5 ms. Additionally, we show that working in the (4,1)-(3,2) charge configuration enables a latched readout window that is larger and more tunable than typical charge configurations, because the size of the readout window is determined by an orbital splitting rather than a valley splitting.