Long-distance single photon transmission from a trapped ion via quantum frequency conversion

TL;DR

This paper demonstrates the successful transmission of single photons emitted by a trapped ion over 10 km of optical fiber using quantum frequency conversion, preserving their quantum properties for potential quantum communication applications.

Contribution

It introduces a system that converts ion-emitted photons to telecom wavelengths for long-distance transmission while maintaining their quantum characteristics.

Findings

Non-classical photon statistics preserved after transmission

Photon temporal shape remains intact after conversion and transmission

Achieved 10 km fiber transmission of single photons from a trapped ion

Abstract

Trapped atomic ions are ideal single photon emitters with long lived internal states which can be entangled with emitted photons. Coupling the ion to an optical cavity enables efficient emission of single photons into a single spatial mode and grants control over their temporal shape. These features are key for quantum information processing and quantum communication. However, the photons emitted by these systems are unsuitable for long-distance transmission due to their wavelengths. Here we report the transmission of single photons from a single $^{40}\text{Ca}^{+}$ ion coupled to an optical cavity over a 10 km optical fibre via frequency conversion from 866 nm to the telecom C-band at 1,530 nm. We observe non-classical photon statistics of the direct cavity emission, the converted photons and the 10 km transmitted photons, as well as the preservation of the photons' temporal shape throughout. This telecommunication ready system can be a key component for long-distance quantum communication as well as future cloud quantum computation.