Thanks to the internet, an email can be sent between two people much faster than a letter in the mail a few years ago; or two hundred years ago when you had to use a carrier pigeon or a carrier horse.
Similarly, computing and quantum cryptography represent major advances in technology, as crucial as the development of laser rays.
One of the reasons we don’t yet have a quantum Internet lies in the fact that we cannot send quantum information over long distances.
However, today, teams of researchers are able to teleport quantum information while continuing to break records in terms of distance.
Quantum Teleportation: a new distance record
In 2014, for the first time ever, the team at the University of Geneva, led by the physicist Nicolas Gisin, successfully managed to teleport a photon at its quantum state on more than 25 km and this, instantly.
The particle found itself in a crystal, via a fiber optic cable.
The previous record in this area established the instantaneous displacement of a proton’s quantum state on six kilometres.
Today, research conducted by the United States and Japan has set a new record, by teleporting a photon inside an optical fiber over a distance of 102 Km (four times higher than the previous record set in Switzerland).
This fantastic experience brings us a little closer to teleportation proving that the perfect transfer of information is increasingly well mastered and that, in the near future, we’ll be transmitting information through photons rather than by email.
This distance record establishes a new level in the world of quantum teleportation and also opens the way towards a future global quantum network intended for secured satellite communications.
All information provided by a photon being instantly on another remote photon, the process would provide not only an ultra-fast internet (the information repeating and circulating at an infinite speed) but also absolutely secure, resistant to all kinds of hacking.
How does Quantum Internet Work?
Although the name is inspired by the teleportation commonly used in fiction (e.g. Star Trek teleportation) quantum teleportation concerns only the transfer of information of « quantum states”, from one place to another without having to move a physical particle along with it.
From ” bit ” to ” qubit “
Our Internet has a physical infrastructure and our computer sends messages on the Internet as a sequence of bytes, each byte being itself a sequence of bits (0s and 1s).
These two binary states, 0 and 1, are transported by thousands of kilometres of cables crisscrossing the oceans or by optical fibers, from one computer to another and circulating on the Internet via routers.
With quantum computing, our quantum computer transmits via network “quantum bits “ or “qubits” instead of bit.
The qubit actually corresponds to the information conveyed by a system within a “superposed state”.
For example, if I want to communicate by quantum Internet with one of my friends, I will generate a photon in a superposed state and send it to my friend. My friend gets the photon carrying the information and this way we can both communicate.
It is these photons that encode and carry encrypted information and will play the role of “bits packet”.
The Quantum Computer
The “superposed” state of these photons (known as the superposition principle) states that a particle a particle may have several different states.
Applied to computers, this mechanism greatly enhances the ability of signals that carry the information. Instead of having only two values , as it is now the case for the “bits”, made of 0 or 1, the ” qubits ” can take a multitude of values.
The quantum computer will therefore use the concept of quantum superposition via the qubit or “quantum bit” which can have the values “0” and “1” at the same time (remember Schrödinger and his “dead or alive” cat?).
For information, a photon with 250 quantum states may contain more information than there are atoms in the universe.
Currently, the technology used to send a quantum message between A and B, with a single optical fiber cable length. However, redirecting the message to a C, D or E recipient is problematic since the process alters the message.
For example, the quantum web of Los Alamos National Labs – Laboratory of the US Energy Department does not work like a computer to computer network, as the classic internet work. The quantum web is in the form of a central server that connects all nodes in a network, but no other connection between the nodes.
Photons loaded with Information
This is achieved through the phenomenon in quantum mechanics known as quantum entanglement, which allows two quantum objects (placed in an ” entangled state”) to share the same “quantum state”. The two particles have a correlation, despite the fact that they aren’t touching and transmitting information to one another.
This means that if you influence an object, you also influence the other, despite the large spatial distances.
By using two “entangled” photons and by encoding the information in these “quantum states”, the physicists have demonstrated the ability to transmit quantum information from one place to another.
Of course, we are talking here of quantum state and not the photon as a whole. The photon’s state acts as information that can be teleported along great distances using the optical fiber. The quantum state of the photon is able to preserve information under extreme conditions, including the difference between traveling as light or becoming stored in the crystal like matter.
Félix Bussières, who works in the team of Nicolas Gisin explained that:
“the quantum state of the two elements of light, these two entangled photons which are like two Siamese twins, is a channel that empowers the teleportation from light into matter.”
Perfect security for data exchange
Communications security is not a new issue. The Internet that we currently use is fast but not very secure. What if quantum cryptography is the perfect solution to secure Internet?
With quantum cryptography, considered the most powerful way to secure the communication systems, it is impossible to copy data encoded in a quantum state and the very act of reading data encoded in a quantum state changes the state.
It is thus possible to transmit a secret encryption key between two remote systems, ensuring its security.
“A quantum internet would be slower but completely safe, “said Professor Alex Lvovsky at the International Conference on Quantum Information in Moscow.
The technology is of great interest to Banks, military services and other organizations that are always looking for the perfect security solution.
“We think that within 25 years, all the asymmetrical systems will fall. Until then, it will be necessary to find an alternative solution. It will be a very significant change, “says Renaud Lifshitz, a security researcher.
But before it will be made available to the average people, quantum internet will first be available to military services, science and big business, such as banks, whose activity and survival depends on the security of their sensitive data. Or, it will be made available to the public, but not entirely (e.g. use of the quantum Internet only when we need to transmit sensitive data such as a credit card number).
Applied to Internet, quantum cryptography has some limitations. It is possible to ensure the integrity of the transmitted key only from point A to point B, since transmitting a message to a point C would require reading the message, in order to copy it and therefore editing it. Physically, it also requires limiting transmissions to a few tens of kilometres.
Therefore, this attractive hypothesis is not ready immediately: researchers must use ultra-sensitive detectors that can measure the energy of a single photon; moreover, the ” quantum effect” occurs only at very low, almost interstellar, temperatures ( -273 ° C).