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Today's Topics:
1. Quantum state teleported between quantum dots at telecoms
wavelengths (Stephen Loosley)
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Message: 1
Date: Sun, 18 Jan 2026 20:01:55 +1030
From: Stephen Loosley <[email protected]>
To: "link" <[email protected]>
Subject: [LINK] Quantum state teleported between quantum dots at
telecoms wavelengths
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
Quantum state teleported between quantum dots at telecoms wavelengths
By Isabelle Dum? 14 Jan 2026
https://physicsworld.com/a/quantum-state-teleported-between-quantum-dots-at-telecoms-wavelengths/
Physicists at the University of Stuttgart, Germany have teleported a quantum
state between photons generated by two different semiconductor quantum dot
light sources located several metres apart.
Though the distance involved in this proof-of-principle ?quantum repeater?
experiment is small, members of the team describe the feat as a prerequisite
for future long-distance quantum communications networks.
?Our result is particularly exciting because such a quantum Internet will
encompass these types of distant quantum nodes and will require quantum states
that are transmitted among these different nodes,? explains Tim Strobel, a PhD
student at Stuttgart?s Institute of Semiconductor Optics and Functional
Interfaces (IHFG) and the lead author of a paper describing the research.
?It is therefore an important step in showing that remote sources can be
effectively interfaced in this way in quantum teleportation experiments.?
In the Stuttgart study, one of the quantum dots generates a single photon while
the other produces a pair of photons that are entangled ? meaning that the
quantum state of one photon is closely linked to the state of the other, no
matter how far apart they are. One of the photons in the entangled pair then
travels to the other quantum dot and interferes with the photon there. This
process produces a superposition that allows the information encapsulated in
the single photon to be transferred to the distant ?partner? photon from the
pair.
Quantum frequency converters
Strobel says the most challenging part of the experiment was making photons
from two remote quantum dots interfere with each other. Such interference is
only possible if the two particles are indistinguishable, meaning they must be
similar in every regard, be it in their temporal shape, spatial shape or
wavelength. In contrast, each quantum dot is unique, especially in terms of its
spectral properties, and each one emits photons at slightly different
wavelengths.
To close the gap, the team used devices called quantum frequency converters to
precisely tune the wavelength of the photons and match them spectrally. The
researchers also used the converters to shift the original wavelengths of the
photons emitted from the quantum dots (around 780 nm) to a wavelength commonly
used in telecommunications (1515 nm) without altering the quantum state of the
photons.
This offers further advantages: ?Being at telecommunication wavelengths makes
the technology compatible with the existing global optical fibre network, an
important step towards real-life applications,? Strobel tells Physics World.
Proof-of-principle experiment
In this work, the quantum dots were separated by an optical fibre just 10 m in
length.
However, the researchers aim to push this to considerably greater distances in
the future.
Strobel notes that the Stuttgart study was published in Nature Communications
back-to-back with an independent work carried out by researchers led by Rinaldo
Trotta of Sapienza University in Rome, Italy. The Rome-based group demonstrated
quantum state teleportation across the Sapienza University campus at shorter
wavelengths, enabled by the brightness of their quantum-dot source.
Quantum photonics network passes a scaling-up milestone
?These two papers that we published independently strengthen the measurement
outcomes, demonstrating the maturity of quantum dot light sources in this
domain,?
Strobel says. Semiconducting quantum dots are particularly attractive for this
application, he adds, because as well as producing both single and entangled
photons on demand, they are also compatible with other semiconductor
technologies.
Fundamental research pays off
Simone Luca Portalupi, who leads the quantum optics group at IHFG, notes that
?several years of fundamental research and semiconductor technology are
converging into these quantum teleportation experiments?.
For Peter Michler, who led the study team, the next step is to leverage these
advances to bring quantum-dot-based teleportation technology out of a
controlled laboratory environment and into the real world.
Strobel points out that there is already some precedent for this, as one of the
group?s previous studies showed that they could maintain photon entanglement
across a 36-km fibre link deployed across the city of Stuttgart.
?The natural next step would be to show that we can teleport the state of a
photon across this deployed fibre link,? he says. ?Our results will stimulate
us to improve each building block of the experiment, from the sample to the
setup.?
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