Researchers at the Institute of Semiconductor Optics and Functional Interfaces (IHFG) at the University of Stuttgart have achieved a decisive breakthrough in the development of quantum repeaters by successfully teleporting quanta between photons originating from two distinct quantum dots. This advancement, detailed in Nature Communications, addresses a critical hurdle in establishing a secure quantum internet. By utilizing quantum teleportation – a process transferring information between photons while preserving its unknown state – the team, led by Prof. Peter Michler, aims to overcome the limitations of signal loss in optical fibers, which currently require renewal approximately every 50 kilometers. This innovation serves as a crucial step towards building functional nodes for a future quantum internet.
Researchers at the University of Stuttgart achieved a breakthrough in developing quantum repeaters, a key component for a future quantum internet. They successfully teleported quantum information between photons originating from different quantum dots – a first-of-its-kind achievement. This addresses a major technical hurdle, as generating indistinguishable photons from separate locations is extremely challenging. The experiment utilized nanometer-sized semiconductor islands to generate photons with defined properties, paving the way for extending quantum communication distances.
A core challenge in building a quantum internet is the limited range of light signals in optical fibers, typically requiring renewal every 50 kilometers. Traditional amplification isn’t possible with quantum information, necessitating quantum repeaters. These repeaters transfer information from one photon to another via quantum teleportation, as long as the information remains unknown. The Stuttgart team demonstrated this process over a 10-meter distance, building on previous work showing entanglement integrity after a 36-kilometer transmission within Stuttgart.
Current success rates for teleportation stand at just over 70%, with fluctuations in quantum dots creating slight differences in photons. Researchers are focused on improving semiconductor fabrication techniques to minimize these variations. The project, part of the “Quantenrepeater.Net (QR.N)” network involving 42 partners, aims to test quantum repeater technology in optical fiber networks and build upon the groundwork laid by the earlier “Quantenrepeater.Link (QR.X)” initiative.
Quantum Repeaters and Information Transfer
Researchers at the University of Stuttgart have achieved a breakthrough in developing quantum repeaters by successfully teleporting quantum information between photons originating from different quantum dots. This involved transferring the polarization state of one photon to another, utilizing entangled photon pairs and “quantum frequency converters” to compensate for differences between the photons. This is crucial because quantum information cannot be simply amplified like conventional signals in fiber optic cables, necessitating these repeaters to renew the information.
The experiment relied on generating nearly identical photons from separate quantum dots, a significant technical challenge. Semiconductor islands with fixed energy levels were developed to produce individual photons with defined properties. These quantum dots were initially separated by only 10 meters, but prior work demonstrated entanglement remained intact after 36 kilometers of transmission through Stuttgart. The current teleportation success rate is just over 70%, with ongoing efforts to improve it through advancements in semiconductor fabrication.
Quantum repeaters are essential nodes for a future quantum internet, designed to overcome the limitations of signal degradation in fiber optic cables. The research is part of the “Quantenrepeater.Net (QR.N)” project, involving 42 partners, and builds on previous work to explore and test this technology. The goal is to create a secure communication network leveraging quantum physics, protected against eavesdropping by relying on the laws of quantum mechanics.
For the first time worldwide, we have succeeded in transferring quantum information among photons originating from two different quantum dots.
Prof. Peter Michler
Advancing Quantum Teleportation Technology
Researchers at the University of Stuttgart achieved a breakthrough in quantum repeater technology by successfully teleporting quantum information between photons originating from different quantum dots. This marks the first time this has been accomplished, overcoming a significant hurdle in building a quantum internet. The experiment utilized nanometer-sized semiconductor islands to generate photons with defined properties, enabling the transfer of polarization state from one photon to another via entanglement and quantum frequency converters.
This advancement addresses a key limitation of quantum communication: signal loss over distance. Traditional light signals require amplification every 50 kilometers, a process incompatible with quantum information which cannot be copied. Quantum teleportation, facilitated by quantum repeaters, allows information to be transferred between photons, renewing the signal without violating quantum principles. The Stuttgart experiment linked quantum dots separated by 10 meters, with prior work demonstrating entanglement over 36 kilometers within Stuttgart city limits.
Current success rates for teleportation stand at just over 70%, and researchers are working to improve this through advancements in semiconductor fabrication. The goal is to minimize fluctuations in the quantum dots, generating more identical photons to optimize the process. This research, funded by the Federal Ministry of Research, Technology and Space as part of the “Quantenrepeater.Net (QR.N)” project, is a crucial step toward a more secure, quantum-based internet infrastructure.
