Teleportation is no longer only associated with science fiction. Today it is now possible in a kind of reality, more precisely in the infinitely small and in quantum bits in particular, which are known as qubits. Where digital information is based on bits – strings of 0s and 1s – qubits are superpositions of 0s and 1s, thus greatly multiplying the field of possibilities and computing power.
What does this have to do with teleportation? These qubits have been teleported by a joint American-Canadian team over a distance of 44 Km and with fidelity of 90 %. Take heed however that as opposed to what the word teleportation may lead us to believe, in this case there is no transfer of matter or energy, and this is where we leave science fiction behind.
In the case of quantum teleportation, it isn’t the particles themselves that are transported but their state. According to the quantum entanglement principle, described in 1935 by Einstein and two other physicists, Podolsky and Rosen, two particles form a system linked in such a way that modifications to the characteristics of one lead to simultaneous changes to the other.
Some research teams had already attempted to reproduce this teleportation experimentally. In January 2003, scientific journal Nature announced that the team of Nicolas Gisin, from the physics department of the University of Geneva (UNIGE), had performed the first ever long-distance teleportation in History, by transporting the state of a photon onto another photon situated 2 km away. The same team struck again three years later according to a UNIGE press release.
Today, in North America, the experiments carried out by researchers from Fermilab, AT&T, Caltech (California Institute of Technology), Harvard University, NASA’s Jet Propulsion Laboratory, and the University of Calgary therefore set a new record for distance. In choosing a traditional fibre optic network, they have demonstrated, among other things, that it is possible to use existing infrastructures.
This exploit, which led to a publication in the journal PRX Quantum, has opened the door a bit more to a quantum internet, as identified in a U.S. Department of Energy report published in February 2020. By guaranteeing unparalleled flow rate and security of exchanges, the potential benefits of this quantum internet are numerous. It would in particular be physically impossible to intercept information without altering it and being detected.
For example, wireless networks use the Wi-Fi Protected Access (WPA) protocol to secure data between a Wi-Fi hotspot and a terminal, whereby a key enables decryption of the encrypted communication. If the key is intercepted by a hacker, they can read all of the exchanges.
As for photons linked by quantum entanglement, they are inseparable, so it is therefore impossible for a third party to observe one without altering the other. Any attempt at spying will be immediately detected by the emitter.
“If someone attempts to read the information that is contained in the photons, you will realise” explains Dr Christophe Simon, a professor of physics at the University of Calgary, on Radio Canada. “Observation changes the system, therefore it is not really possible to observe a quantum system without changing it.”
Such quantum secure communication systems already exist but remain limited to fundamental research. For the Canadian scientist, in time they will become accessible as small photonic chips on board our computers.
According to the U.S. Department of Energy, the initial users of this inviolable information system would be banking and health services, national security and aircraft communications: “Eventually, the use of quantum networking technology in mobile phones could have broad impacts on the lives of individuals around the world.”
No loss of value
The quantum internet is also set to become the extension of the quantum computer, whose performances are increased greatly in comparison to traditional computers. China thus recently claimed to have reached quantum supremacy with a quantum computer 100 trillion times faster than the most advanced supercomputer.
This network of the future, linking up quantum computers with one another, could allow the exchange of large quantities of data, according to an article published by the University of Calgary.
From this point of view, the experimentation carried out by the American-Canadian team, with its fidelity of 90 %, is a “step toward a workable quantum network”, as stated by the authors of a study published in PRX Quantum.
“We are very proud to have achieved this milestone on sustainable, high-performing, and scalable quantum teleportation systems,” says Maria Spiropulu, a professor of physics at Caltech. “The results will be further improved with system upgrades we are expecting to complete by the second quarter of 2021.”
This fidelity is de facto a key element. With traditional optic fibre, the photons, elementary particles of light, transmit information but lose strength over distance. Quantum teleportation would enable the transmission of information over distance with no loss of value.
The Sino-American Battle
In any event, this promising experimentation should shed light on a national quantum internet project in the United States, as revealed in a press release in July 2020 by the U.S. Department of Energy. Plans are already underway to create a quantum internet network linking up several Chicago research institutes.
China has also entered the battle. In 2017, researchers from The Middle Kingdom communicated, in an article in Science, that they had succeeded in the quantum transmission of data from space to several stations in Tibet, over 1,200 kilometres away.