Téléportation quantique - réalité ou fiction ?

Using Optical Fiber For Quantum Teleportation

Global digital communication relies on the quick and efficient transfer of data at the speed of light through a complex network of optical fibers. This is acceptable for classical computing, which uses binary strings of 0 and 1.

However, as quantum computing becomes increasingly close to being a commonly used tool for encryption, scientific research, and other applications, the question of how to transfer quantum data from one quantum computer to another arises.

For a long time, this was believed to be almost impossible. Each quantum computer was destined to work in isolation from each other, reducing their potential.

This is quickly becoming an important problem to solve for the tech industry, especially as new scalable designs of quantum chips have just been unveiled.

So this is an important stepping stone that researchers at Northwestern University, Ciena Corporation, and NuCrypt LCC have discovered: quantum state can be preserved and transferred in optical fiber alongside a “normal” data stream.

They published their results in Optica, titled “Quantum teleportation coexisting with classical communications in optical fiber¹".

Quantum Teleportation

Bien qu'elle ressemble à un concept fantaisiste tiré d'un film de science-fiction, la téléportation quantique est en fait un phénomène réel étudié depuis des décennies.

Cela se produit lorsque deux particules différentes sont "appariées/liées" ensemble, ce que l'on appelle l'intrication quantique.

In this case, when two particles are linked, regardless of the distance between them, they exchange information over great distances — without physically carrying it. In some cases, it could even be possible that the information exchange happens quicker than the speed of light, something theoretically impossible.

La manière dont il fonctionne et ce qu'il signifie pour l'aspect fondamental de notre réalité fait encore l'objet de vifs débats parmi les physiciens quantiques. Cependant, nous savons qu'il s'agit d'un effet quantique très réel et mesurable, qui pourrait permettre des communications parfaitement sécurisées et instantanées.

Radically Different Communications

A Needle In A Moving Haystack

Until now, it was assumed that no quantum state could be transferred through optical fiber, as any individual entangled photon would be drawn in the other billions traveling with it and lose its unique quantum state.

“By performing a destructive measurement on two photons — one carrying a quantum state and one entangled with another photon — the quantum state is transferred onto the remaining photon, which can be very far away.

The photon itself does not have to be sent over long distances, but its state still ends up encoded onto the distant photon. Teleportation allows the exchange of information over great distances without requiring the information itself to travel that distance.”

Jordan Thomas – Ph.D. at Northwestern University.

The key insight was to measure if there was not some specific condition in the optic fiber that would not disrupt the quantum entanglement.

After conducting in-depth studies of how light scatters within fiber optic cables, the researchers found a less crowded wavelength of light to place their photons, the 1290-nm quantum channels. Then, they added special filters to reduce noise from regular Internet traffic.

Of course, while this sounds easy, the actual experimental setup was all but simple, with the published scientific paper giving us a glimpse of how complex the whole experiment truly was:

Source : Optica

New Telecommunications

As optical fiber transfer photons from point A to point B, it was already known they could carry a quantum state in them. But this is the first time that it has been demonstrated that this can happen at the same time other non-quantum data are transferred as well.

This means that a very different information transfer process is occurring, one relying on a single photon at a time instead of the usual million of photons.

“In optical communications, all signals are converted to light. While conventional signals for classical communications typically comprise millions of particles of light, quantum information uses single photons.”

Pr Prem Kumar – Director of the Center for Photonic Communication and Computing at Northwestern University

From Initial Prototype To Larger Ambitions

More Optical Fiber

The first test was conducted on a 30km-long (18.6 miles) optical fiber, with high-speed Internet traffic passing through.

The next step for the researchers will be to experiment with much longer distances, to see how far they could push for this new method of distant communication.

This has so far been conducted with lab-only optical fiber. Another set of tests will experiment with real-world in-ground optical cables and see how well they work with the preexisting global network of Internet optical fiber.

Expanding Quantum Applications

Another part of the ongoing investigation will be to use two pairs of entangled photons, rather than one pair. This would check what is happening about another quantum phenomenon called, entanglement swapping.

Entanglement swapping is a protocol to transfer quantum entanglement from one pair of particles to another, even if the second pair of particles has never interacted.

This is an important extra tool for potential future quantum telecommunications because it would lead to distributed quantum applications like quantum networks. These networks may support safely transferring quantum information over long routes.

“Quantum teleportation has the ability to provide quantum connectivity securely between geographically distant nodes. But many people have long assumed that nobody would build specialized infrastructure to send particles of light.

If we choose the wavelengths properly, we won’t have to build new infrastructure. Classical communications and quantum communications can coexist.”

Pr Prem Kumar – Director of Center for Photonic Communication and Computing at Northwestern University

This would be a big step in quantum-powered encryption, as by utilizing swapped entanglements between particles’ pairs, it is possible to generate secure encryption keys that should be protected against eavesdropping.

Another effect would be to allow for ultra-long distance transfer of quantum states, through a method called quantum repeaters. By performing entanglement swapping regularly, it could “refresh” the quantum state and avoid any data loss over long distances.

Investir dans l'informatique quantique

Quantum computing is still an emerging field, but investors can already access it through companies that are developing it.

You can invest in quantum-related companies through many brokers, and you can find here, on securities.ioNos recommandations pour les meilleurs courtiers en les États-Unis, Canada, Australie, le Royaume-Uni, ainsi que de nombreux autres pays.

If you are not interested in picking specific quantum computing companies, you can also look into quantum computing ETFs like Defiance Quantum ETF (QTUM), which will provide a more diversified exposure to capitalize on the quantum computing industry.

You can learn more about quantum computing in “L'état actuel de l'informatique quantique” and the largest companies in the sector in “5 Best Quantum Computing Companies" & "Les 10 premières entreprises d'informatique hors silicium".

Entreprise d'informatique quantique

1. Alphabet Inc.

Google est très actif dans le domaine de l'informatique quantique, principalement par l'intermédiaire de son laboratoire Google Quantum AI et de son campus Quantum AI à Santa Barbara.

L'ordinateur quantique de Google est entré dans l'histoire en 2019 lorsqu'il a affirmé avoir atteint la "suprématie quantique" avec sa machine Sycamore. La machine a effectué en 200 secondes un calcul qui aurait pris 10 000 ans à un superordinateur classique.

This is now dwarfed by its newest chip’s performance, called Saule. This is the very first quantum computing chip is an error rate low enough, that the more qubits you add, the less error you get. It makes it the very first scalable quantum chip design.

Mais la plus grande contribution de Google sera peut-être dans le domaine des logiciels, une activité dans laquelle il a un palmarès impressionnant, en fait meilleur que dans le matériel (recherche, GSuit, Android, etc.).

D'ores et déjà, Quantum AI de Google met à disposition une suite de logiciels conçus pour aider les scientifiques à développer des algorithmes quantiques.

Elle plaide également ouvertement en faveur de "chercheurs, ingénieurs et développeurs à nous rejoindre dans cette aventure en consultant notre site internet logiciel libre et des ressources éducatives, y compris notre nouveau cours sur Courseraoù les développeurs peuvent apprendre l'essentiel de la correction quantique des erreurs et nous aider à créer des algorithmes capables de résoudre les problèmes du futur."

Thanks to this open approach, Google is now leading in hardware as well as its cloud solutions. Google might be one of the companies setting the standards of quantum computing software and quantum programming, giving it a privileged position to direct the field’s future evolution.

Meanwhile, AI solutions, including Waymo’s self-driving car, might become the new revenue driver for Alphabet, which still holds a massively dominant position in the search & ads industries.

Vous pouvez en savoir plus sur les activités de Google qui ne sont pas liées au quantique, en particulier les annonces et l'IA, dans notre rapport dédié de décembre 2024.

2. Ciena Corporation

A partner is the research project that demonstrated quantum teleportation in optical fiber, Ciena Corporation is a global leader in optical and routing systems, services, and automation software.

Ciena is by far the world’s largest company ex-China in the optical market, controlling more than 25% of the market. It is present in 70 countries.

Source : Ciena Corporation

The company sees the demand for bandwidth as exploding in the next 4 years, driven by the demand from AI applications.

Source : Ciena Corporation

This has prompted the company to use its strong position in optical networks to expand into new markets relevant to the AI boom, notably en raison de many AI applications requiring new localized data centers, en raison de laws about privacy and cross-border data flow, as well as the emergence of disaggregated data centers, requiring more optical network capacity.

Source : Ciena Corporation

If existing networks of optical fiber prove to be usable for transmitting quantum data, this could prove a new booming sector for the optical network industry. This would make the future of the sector even more promising, as quantum computing could give it a massive boost after the already exploding demand from AI applications.

Référence de l'étude :

^{1. Thomas, J. M., Yeh, F. I., Chen, J. H., Mambretti, J. J., Kohlert, S. J., Kanter, G. S., & Kumar, P. (2024). Quantum teleportation coexisting with classical communications in optical fiber. Optica, 11(12), 1700–1707. https://doi.org/10.1364/OPTICA.11.001700}