An international research team involving Paderborn University has achieved the first successful quantum teleportation of the polarization state of a single photon emitted from one quantum dot to another spatially separated quantum dot. This breakthrough utilized quantum dots and involved experiments conducted over a 270-meter free-space connection, with results recently published in Nature Communications. Led by Prof. Dr. Klaus Jöns and Prof. Dr. Rinaldo Trotta, this work demonstrates that semiconductor quantum dot-based light sources can serve as key technology for future quantum communication networks, representing an essential step towards scalable quantum relays and a practical quantum internet.
Quantum Teleportation Between Quantum Dots
Researchers have, for the first time, successfully demonstrated quantum teleportation between two different quantum dots. This breakthrough involved transferring the polarisation state of a single photon emitted from one quantum dot to a photon from another, spatially separated dot. The experiment utilized a 270-meter free-space connection between university buildings, marking a significant step towards building future quantum communication networks and scalable quantum relays for a quantum internet.
The achieved teleportation fidelity reached 82 ± 1 percent, exceeding the classical limit by over ten standard deviations. This high fidelity demonstrates the quality of maintaining quantum states during the teleportation process. The quantum dots themselves were developed at Johannes Kepler University Linz, with nanofabrication carried out at the University of Würzburg, highlighting a collaborative European research network focused on advancing quantum technology.
This success builds upon over a decade of strategic planning by Professors Jöns and Trotta, who previously mapped out how quantum dots could be used for quantum communication. The team is now focused on demonstrating “entanglement swapping” between quantum dots, aiming to create the first quantum relay using two deterministic sources of entangled photon pairs – sources capable of reliably generating single photons.
Successful European Research Collaboration
Successful quantum teleportation was achieved through long-standing collaboration between multiple European research institutions. Scientists from Paderborn University (Germany) worked closely with a team at the Sapienza University of Rome (Italy), building on a roadmap developed over ten years ago. This collaboration focused on using quantum dots as sources of entangled photon pairs for quantum communication and teleportation protocols. The experiment demonstrated teleportation of a photon’s polarization state between spatially separated quantum dots, a critical step for future quantum networks.
The research leveraged expertise from several locations across Europe. Quantum dots were developed at Johannes Kepler University Linz, while nanofabrication of resonators occurred at the University of Würzburg. The teleportation experiment itself, including a 270-meter free-space link between university buildings, was conducted by the Rome team. Technologies like GPS-supported synchronization, single-photon detectors, and active stabilization systems were essential to overcome atmospheric turbulence during the experiment.
This collaborative effort resulted in a teleportation fidelity of 82 ± 1 per cent—exceeding the classical limit by over ten standard deviations. This achievement paves the way for developing the first quantum relay with two deterministic sources of entangled photon pairs. Simultaneously, a separate research team in Stuttgart and Saarbrücken achieved a similar result, marking a significant milestone for European quantum research and demonstrating the strength of coordinated scientific effort.
The experiment impressively demonstrates that quantum light sources based on semiconductor quantum dots can represent a key technology for future quantum communication networks. The successful quantum teleportation between two different quantum emitters is an essential step towards scalable quantum relays and thus a practical implementation of the quantum internet.
Prof Dr Klaus Jöns
Progress Towards a Functional Quantum Internet
Researchers have achieved a key breakthrough towards a functional quantum internet by successfully demonstrating quantum teleportation between two spatially separated quantum dots. This involved transferring the polarisation state of a photon emitted from one quantum dot to a photon from another, accomplished across a 270-metre free-space connection. This is significant for future quantum communication networks because it moves beyond using a single source for photons, a previous limitation in developing quantum relays.
This experiment achieved a teleportation fidelity of 82 ± 1 per cent, exceeding the classical limit by more than ten standard deviations. This high fidelity indicates the quality of maintaining quantum states during the teleportation process. The success relied on a Europe-wide collaboration, with quantum dots developed at Johannes Kepler University Linz and nanofabrication completed at the University of Würzburg. GPS-supported synchronisation and systems to compensate for atmospheric turbulence were also critical.
This work paves the way for demonstrating “entanglement swapping” between two quantum dots, representing the first quantum relay utilizing two deterministic sources of entangled photon pairs. Deterministic sources generate single photons reliably, a significant challenge previously. Simultaneously, a separate team in Stuttgart and Saarbrücken achieved a similar result using frequency conversion, marking an important milestone for European quantum research.
