# Telecom-wavelength quantum teleportation using frequency-converted photons from remote quantum dots

## TL;DR

Researchers achieved quantum teleportation using photons from remote quantum dots, a key step for building a quantum internet.

## Contribution

The study demonstrates all-photonic quantum teleportation using semiconductor quantum dots with telecom-wavelength interference.

## Key findings

- Quantum teleportation was achieved with a fidelity of 0.721(33), exceeding classical limits.
- Two-photon interference at telecom wavelengths was enabled using polarization-preserving frequency converters.
- The experiment used remote GaAs quantum dots emitting in the near-infrared.

## Abstract

A global quantum internet is based on scalable networks, which require reliable quantum hardware. Among them are quantum light sources providing deterministic, high-brightness, high-fidelity entangled photons and quantum memories with coherence times exceeding the millisecond range. Long-distance operation demands quantum light sources emitting at telecommunication wavelengths. A cornerstone for such networks is the demonstration of quantum teleportation. Here, we realize full-photonic quantum teleportation employing semiconductor quantum dots, which can fulfill all the aforementioned requirements. Two remote GaAs quantum dots, emitting in the near-infrared, are used: one as an entangled-photon pair source and the other as a single-photon source. During the experiment, the single photon is prepared in conjugate polarization states and interfaced with the biexciton emission of the entangled pair employing a polarization-selective Bell state measurement. This process teleports the respective polarization state onto the exciton emission of the entangled pair. The frequency mismatch between the triggered sources is erased using two polarization-preserving quantum frequency converters, enabling remote two-photon interference at telecommunication wavelengths, yielding a visibility of 30(1)%. A post-selected teleportation fidelity up to 0.721(33), significantly above the classical limit, demonstrates successful quantum teleportation between light from distinct sources. These results mark an important development for semiconductor-based quantum light sources.

Quantum-dot-based single photon sources represent a promising resource for future quantum networks. Here, the authors realize all-photonic quantum teleportation using photons from two remote near-infrared-emitting quantum dots, using polarization-preserving quantum frequency converters to enable two-photon interference at telecom wavelength.