量子テレポーテーション – 事実かフィクションか？

光ファイバーを用いた量子テレポーテーション

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.

しかし、量子コンピューティングが暗号化、科学研究、その他の用途で一般的に使用されるツールにますます近づくにつれて、量子データをある量子コンピュータから別の量子コンピュータへ転送する方法という問題が浮上しています。

長い間、これはほぼ不可能だと考えられていました。各量子コンピュータは互いに孤立して動作する運命にあり、その可能性が制限されていました。

これはテック業界にとって重要な課題となりつつあり、特に新しいスケーラブルな量子チップ設計がちょうど発表されたことが背景にあります。

したがって、Northwestern University、Ciena Corporation (CIEN ) 、NuCrypt LCC の研究者が発見した重要なステップは、光ファイバー内で「通常」のデータストリームと並行して量子状態を保存・転送できることです。

They published their results in Optica, titled “光ファイバーにおける古典通信と共存する量子テレポーテーション¹”.

量子テレポーテーション

While sounding like some fanciful concept from a science-fiction movie, quantum teleportation is actually a real phenomenon studied for decades.

これは、2 つの異なる粒子が「ペア/結合」される現象、すなわち量子もつれと呼ばれるものが起こるときに発生します。

この場合、2 つの粒子がリンクされると、距離に関係なく情報を遠距離で交換します――物理的に情報を運ぶことなくです。場合によっては、情報交換が光速よりも速く起こる可能性さえあり、理論的には不可能とされています。

その仕組みや現実への意味は量子物理学者の間で激しく議論されていますが、これは非常に実在し測定可能な量子効果であり、完全に安全で瞬時の通信を可能にする可能性があります。

根本的に異なる通信

動く干し草の中の針

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.

光ファイバー内で光が散乱する様子を詳細に研究した結果、研究者は光子を配置するために混雑が少ない 1290 nm の量子チャネルという波長を見つけました。その後、通常のインターネットトラフィックからのノイズを低減する特別なフィルターを追加しました。

もちろん、これは簡単に思えるかもしれませんが、実際の実験設定は決して単純ではなく、公開された科学論文は実験全体がいかに複雑であったかを垣間見せています:

出典: Optica

新しい電気通信

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

初期プロトタイプから大きな野望へ

より多くの光ファイバー

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.

量子応用の拡大

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.

量子コンピューティングへの投資

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.io, our recommendations for the best brokers in the USA, Canada, Australia, the UK, as well as many other countries.

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 “The Current State of Quantum Computing ” and the largest companies in the sector in “5 Best Quantum Computing Companies” & “Top 10 Non-Silicon Computing Companies”.

量子コンピューティング企業

1. Alphabet Inc.

Google は量子コンピューティングに非常に積極的で、主に Google Quantum AI ラボとサンタバーバラの Quantum AI キャンパスを通じて活動しています。

Google の量子コンピュータは 2019 年に歴史的な成果を上げ、Sycamore マシンで「量子優位性」を達成したと主張しました。このマシンは 200 秒で計算を完了し、従来のスーパーコンピュータなら 10,000 年かかるとされています。

This is now dwarfed by its newest chip’s performance, called Willow. 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.

しかし、Google の最大の貢献はソフトウェア分野にある可能性があります。ここでの実績はハードウェア（検索、GSuit、Android など）を上回っています。

すでに、Google の Quantum AI は科学者が量子アルゴリズムを開発するのを支援するソフトウェアスイートを提供しています。

It also openly advocates for “researchers, engineers, and developers to join us on this journey by checking out our open source software and educational resources, including our new course on Coursera, where developers can learn the essentials of quantum error correction and help us create algorithms that can solve the problems of the future.”

このオープンなアプローチのおかげで、Google はハードウェアだけでなくクラウドソリューションでもリーダーシップを取っています。Google は量子コンピューティングソフトウェアと量子プログラミングの標準を設定する企業の一つとなり、分野の将来の進化を導く有利な立場にあります。

一方、Waymo の自動運転車を含む AI ソリューションは、検索と広告産業で圧倒的な支配力を保持する Alphabet (GOOG ) にとって新たな収益源になる可能性があります。

You can learn more about Google non-quantum-related activities, especially ads and AI, in our dedicated report from 2024年12月.

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.

出典: Ciena Corporation

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

出典: 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 due to many AI applications requiring new localized data centers, due to laws about privacy and cross-border data flow, as well as the emergence of disaggregated data centers, requiring more optical network capacity.

出典: 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.

研究参照：

^{1. Thomas, J. M., Yeh, F. I., Chen, J. H., Mambretti, J. J., Kohlert, S. J., Kanter, G. S., & Kumar, P. (2024). 光ファイバーにおける古典通信と共存する量子テレポーテーション. Optica, 11(12), 1700–1707. https://doi.org/10.1364/OPTICA.11.001700}