Quantum Teleportation Breakthrough Brings the Quantum Internet Closer

First successful demonstration of quantum teleportation between two different quantum dots.

An international team of researchers that includes scientists from Paderborn University has achieved a major milestone toward building a future quantum internet.

For the first time, the polarization state of a single photon produced by one quantum dot has been successfully transferred to another quantum dot located at a separate physical location. In simple terms, this means the properties of one photon were transmitted to another through quantum teleportation.

The demonstration marks an important step toward practical quantum communication networks. During the experiment, researchers used a 270-meter free-space optical link to connect the systems. The findings have been published in the journal Nature Communications.

Long-term European collaboration brings success

At Paderborn University, a team of doctoral and postdoctoral researchers spent roughly a decade working on optical measurements as well as the analysis and evaluation of experimental data. During this period, the research group led by Professor Klaus Jöns collaborated closely with scientists headed by Professor Rinaldo Trotta at Sapienza University of Rome in Italy.

“The experiment impressively demonstrates that quantum light sources based on semiconductor quantum dots could serve as a key technology for future quantum communication networks. Successful quantum teleportation between two independent quantum emitters represents a vital step towards scalable quantum relays and thus the practical implementation of a quantum internet,” explained Professor Jöns, head of the ‘Hybrid Photonics Quantum Devices’ research group and a member of the board of the Institute for Photonic Quantum Systems (PhoQS) at Paderborn University.

To understand the importance of the work, it helps to consider how entangled quantum systems operate. When several quantum particles become entangled, their properties are linked in such a way that they form a shared system rather than acting independently. Instead of representing a single state tied to one photon, the system can contain multiple possible states at once.

These kinds of quantum systems are essential for technologies such as secure communication, advanced data processing, and quantum computing. In this context, entanglement connects certain properties of photons, while each quantum state represents a unit of information being processed.

“Previously, these photons came from one and the same source, i.e. the same emitter. Although there has been significant progress made in recent years, using distinct quantum emitters to implement a quantum relay between independent parties had previously remained out of reach,” Professor Jöns noted.

About ten years ago, Professor Jöns and Professor Trotta outlined a long-term strategy describing how quantum dots could function as sources of entangled photon pairs for communication and teleportation protocols. “This result shows that our long-term strategic planning has paid off,” Professor Jöns said, adding: “The combination of excellent materials science, nanofabrication, and optical quantum technology was the key to our success.”

Technological excellence across numerous research locations

The achievement relied on expertise and facilities spread across several research institutions in Europe. Quantum dots used in the experiment were fabricated with extremely high precision at Johannes Kepler University Linz. Resonators required for the optical systems were manufactured through nanofabrication by researchers at the University of Würzburg.

Scientists at Sapienza University of Rome carried out the teleportation experiment itself. Their setup included a 270-meter free-space optical connection between two university buildings. The protocol used GPS-assisted synchronization along with ultra-fast single-photon detectors and stabilization systems designed to counteract disturbances caused by atmospheric turbulence. The experiment achieved teleportation state fidelity reaching as high as 82 ± 1 percent. This value exceeds the classical limit by more than ten standard deviations, demonstrating that the quantum teleportation process worked reliably.

Looking ahead: first quantum relay with two deterministic sources

The researchers say the next goal will be to demonstrate entanglement swapping between two quantum dots. Achieving this would create the first quantum relay based on two deterministic sources of entangled photon pairs.

Deterministic quantum sources are capable of producing individual photons with a high level of reliability, essentially on demand. Developing such sources has been one of the major technical challenges in quantum photonics.

Simultaneous progress

At nearly the same time, another research group based in Stuttgart and Saarbrücken reported a related achievement using frequency conversion methods.

Together, these independent efforts represent an important step forward for quantum science in Europe and for the development of technologies that could eventually support a large-scale quantum internet.

Reference: “Quantum teleportation with dissimilar quantum dots over a hybrid quantum network” by Alessandro Laneve, Giuseppe Ronco, Mattia Beccaceci, Paolo Barigelli, Francesco Salusti, Nicolas Claro-Rodriguez, Giorgio De Pascalis, Alessia Suprano, Leone Chiaudano, Eva Schöll, Lukas Hanschke, Tobias M. Krieger, Quirin Buchinger, Saimon F. Covre da Silva, Julia Neuwirth, Sandra Stroj, Sven Höfling, Tobias Huber-Loyola, Mario A. Usuga Castaneda, Gonzalo Carvacho, Nicolò Spagnolo, Michele B. Rota, Francesco Basso Basset, Armando Rastelli, Fabio Sciarrino, Klaus D. Jöns and Rinaldo Trotta, 17 November 2025, Nature Communications.
DOI: 10.1038/s41467-025-65911-9

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