Scientists Successfully Teleport Photons Using Telecom Wavelengths, Paving the Way for a Global Quantum Internet
Featured paper: Telecom-wavelength quantum teleportation using frequency-converted photons from remote quantum dots
Disclaimer: This content was generated by NotebookLM. Dr. Tram doesn’t know anything about this topic and is learning about it.
For decades, the idea of instantaneous travel—or teleportation—has been relegated to the realm of science fiction. But in the world of quantum mechanics, teleportation is a very real, though complex, phenomenon. It’s not about moving matter, but about instantly transferring the information (or quantum state) of one particle onto another.
Now, a team of researchers led by Tim Strobel has achieved a groundbreaking milestone in this field. In a paper published in late 2025, they describe the successful realization of full-photonic quantum teleportation using semiconductor quantum dots (QDs), marking a major step toward building a viable, global quantum internet.
This isn’t just cool science; it’s a fundamental demonstration of reliable quantum hardware necessary for scalable networks.
The Dream of a Global Quantum Internet
Imagine an internet secured by the unbreakable laws of physics, capable of connecting distant super-fast quantum computers and sensors. This is the promise of the quantum internet, and its foundation relies on two things: sources of quantum light (photons) that carry information, and quantum memories to store that information.
Semiconductor quantum dots (QDs)—tiny structures capable of emitting quantum light—have shown immense promise as crucial components in this future network. QDs are efficient sources of both single photons and entangled photon pairs. The ability to achieve quantum teleportation is a crucial cornerstone for making these quantum networks a reality.
However, building a global network requires sending these fragile quantum signals across long distances.
The Wavelength Challenge: Why Fiber Optics Matter
Currently, the backbone of our classical internet is built on standard optical silica fibers. These fibers work best when the light traveling through them is at telecommunication wavelengths (around 1550 nm), as this is where light experiences the least loss and lowest dispersion. If you want quantum information to travel globally, you need your quantum light sources to operate at these telecom wavelengths.
The challenge is that the most efficient quantum dots usually emit light in the near-infrared (NIR) spectrum, around 780 nm. This is the equivalent of trying to transmit a clear message through a noisy channel—the signal degrades quickly over long distances in standard telecom fiber.
Strobel and his colleagues devised an elegant solution: Quantum Frequency Conversion (QFC).
The Quantum Translator: Converting Near-Infrared to Telecom
The researchers used two independent, specialized devices called polarization-preserving quantum frequency converters (QFCs). You can think of these converters as high-tech quantum translators. Their job was to take the photons emitted by the QDs at their native NIR wavelength (~780 nm) and precisely convert them to a common, desired telecom wavelength (1515 nm).
Crucially, this conversion process needed to be “polarization-preserving”. In quantum mechanics, a photon’s polarization (its orientation) is the specific piece of quantum information (or qubit) being carried. If the conversion process messed up the polarization, the quantum information would be lost. The sources confirm that this process worked, fully preserving the high degree of entanglement during conversion. Being at these technologically relevant telecom wavelengths now enables the crucial step of long-distance propagation along standard silica fibers.
The Teleportation Recipe
The experiment required two remote GaAs QDs, each playing a specific role:
- Source I (QD1): The Messenger. This quantum dot served as a single-photon source (SPS), emitting Photon 1. This photon carried the polarization state (the message, $\mid \xi_{1}\rangle$) that was to be teleported.
- Source II (QD2): The Entangled Bridge. This QD generated a pair of entangled photons (Photons 2 and 3). Entangled photons are linked in such a way that measuring the state of one instantly tells you the state of the other, no matter the distance.
Both the message photon (P1) and one entangled partner (P2) were first frequency-converted to the telecom wavelength. They were then sent to a specialized Bell State Measurement (BSM) setup.
The BSM is the core mechanism of teleportation. When the BSM successfully measured Photons 1 and 2 together, it effectively projected them onto a maximally entangled state. This action instantly teleported the original polarization state of Photon 1 onto the second entangled photon, Photon 3, which was traveling separately in the near-infrared receiver.
Beating the Classical Limit
The success of the experiment is measured using a metric called average teleportation fidelity ($\bar{f}$). This measures how accurately the quantum state was transferred. To prove true quantum teleportation, the fidelity must exceed a threshold known as the classical limit, which is 2/3 (or approximately 0.667).
The researchers successfully prepared and teleported three different foundational polarization states. For a highly filtered, 70-picosecond time window—a necessary technique due to the inherent properties of the quantum dots—they measured an average teleportation fidelity of 0.721(33).
This result is significantly above the classical threshold. While the fidelity dropped slightly for longer time windows, the result clearly demonstrates successful quantum teleportation between photons generated by distinct sources.
The scientists also noted that the ability to perform Two-Photon Interference (TPI)—a requirement for the BSM—was key, yielding a visibility of 30(1)% without special filtering, which improved dramatically to 79(1)% with temporal post-selection.
The Road Ahead
This experiment highlights the maturity of quantum dot technology as a robust and reliable source of quantum light. The success of converting photons to telecom wavelengths while preserving their quantum state is crucial for future implementations. Though the physical fiber lengths in this laboratory demonstration were small, the low-loss properties of telecom fibers mean that the high fidelity achieved here could be maintained even if the fiber length were extended by several kilometers.
Future goals focus on optimizing the quantum dot sources themselves to increase the TPI visibility further, which is currently a limiting factor. Achieving improvements here could push the average teleportation fidelity higher, potentially up to 0.85 in an optimized, ideal scenario.
This achievement marks a vital building block—the successful teleportation of a photonic state onto an entangled partner—necessary for more complex quantum architectures, such as entanglement swapping, which is essential for extending quantum communication across truly vast distances.
The ability to perform reliable quantum teleportation using semiconductor components that interface seamlessly with the telecom infrastructure brings the vision of the global quantum internet closer to reality.