Ultrafast high-fidelity state readout of single neutral atom

TL;DR

This paper demonstrates ultrafast, high-fidelity state readout of a single neutral atom using a fiber-based microcavity, significantly improving measurement speed and accuracy for quantum networking applications.

Contribution

It introduces a method coupling a neutral atom with a high-finesse fiber cavity to achieve rapid, high-fidelity quantum state discrimination, surpassing previous limitations.

Findings

Readout fidelity reaches 99.1% within 200 ns

Achieves 99.985% fidelity within 9 microseconds

Enables accelerated state preparation using real-time decision protocols

Abstract

The capability to measure the state of a quantum system is vital to a practical quantum network, for applications including distributed quantum computing and long-distance quantum communication. As a thriving platform for quantum information technology, single neutral atoms suffer from low achievable photon scattering rate and shallow trapping potential, which limits the fidelity and speed of state readout process. Here, by coupling an single neutral atom with a high-finesse fiber-based Fabry-P\'erot microcavity (FFPC) in Purcell regime, we realize strong enhancement of the atomic photoemission rate, which enables ultrafast and high-fidelity discrimination of bright and dark hyperfine states of the atom. The readout fidelity can reach 99.1(2)% within 200 ns and 99.985(8)% within 9 $\mu$s. Furthermore, we demonstrate that state preparation via optical pumping can be efficiently accelerated by real-time decision protocol based on ultrafast state readout. This work paves the way to the implementation of quantum networking protocols with high communication rate and high fidelity.