Scientists from the QuTech Institute at the University of Delft in the Netherlands have made a significant breakthrough in the field of quantum computing. They succeeded in teleporting information in a quantum way, paving the way for a future quantum Internet.
Quantum computing, infinite potential
First of all, it must be understood that quantum computing is completely different from classical computing, since it uses the properties of the quantum world, that is to say of the infinitely small. Indeed, elementary particles do not behave at all in the same way as what we experience in our daily lives, hence the interest of researchers for their properties in the field of computing. For example, they can exist in different states simultaneously.
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It is enough to compare the qubits and the bits to realize the potential of this technology. Bits are processed by classical computers to store information and can only exist as 0 or 1. The qubit, an analog of the bit in quantum computing, can exist as 1 and 0 simultaneously, allowing a quantum computer to perform calculations, for example, far more complex than its traditional counterparts.
For now, the field of quantum computing is still in its infancy; but every step forward is important because it brings us closer to a world of endless possibilities. Eventually, but it’s impossible to know when, quantum computers should be able to perform tasks in minutes that would take existing supercomputers thousands of years.
A three-node quantum network
The Dutch researchers involved in the study discussed today and published in the journal Nature, developed the first three-node quantum network in 2021, and it was this same network that was used for the experiment. You should know that quantum information can be transported by fiber optics, but the photons are lost over long distances, and therefore the information they contain also disappears. The quantum teleportation of information therefore seems to be an ideal solution, but it is still necessary to succeed in implementing it.
QuTech’s three-node network is not fully connected. Placed in a separate laboratory, several meters apart from each other, each of the three nodes dubbed Alice, Bob and Charlie contains a qubit of information made from nitrogen vacancy centers, which are defects in the network carbon atoms of diamond. Only one of the nodes, Bob, contains a memory qubit designed from an adjacent carbon atom. Bob is connected to Alice and Charlie, but the latter two are not connected to each other, as explained in the video below:
Quantum entanglement, essential for the teleportation of information
The first step in teleporting quantum information from a transmitter (Alice) to a receiver (Charlie) is to establish entanglement between their respective qubits. Quantum entanglement is a phenomenon in which two particles form a linked system, and exhibit quantum states that are dependent on each other regardless of the distance between them.
Thus the two cease to be individual particles with definite states of their own and become a system with a single wave function. To achieve this, Alice establishes an entanglement with Bob, and any action that occurs in her is instantly replicated in him. It is then Bob’s turn to set up an entanglement with Charlie. Result: Bob allows Alice and Charlie to establish an entanglement between themselves if they are not connected.
” After preparing an entanglement between Alice and Charlie, the state to be teleported is created and then executed. Then something happens that is only possible in the quantum world: following the measurement, the information disappears on Charlie’s side and immediately appears on Alice’s side. “, explains Ronald Hanson, physicist at QuTech and lead author of the study.
In other words, the information was teleported from one node to another, without crossing either space or fibre; in this way, it cannot be lost en route as is the case with optical fiber, and it is very secure, an essential element for building a functional network.
This diagram details how Alice, the transmitter of information and Charlie, her receiver, achieve quantum entanglement thanks to Bob. Schema: Nature
A small step with big implications
This is not the first time that researchers have achieved quantum teleportation. Five years ago, researchers from the Chinese University of Science and Technology succeeded in teleport photons from Earth to the Micius satellite, in orbit at an altitude of 1,400 kilometers. On the other hand, the quantum teleportation of information carried out by Dutch scientists is a first, and it is much more complex. It can indeed give us a glimpse of what a quantum Internet network would look like.
” Besides the quality of the experiment, the demonstration of a sophisticated quantum communication configuration with three nodes and very elaborate communication algorithms, lays the foundation for its extension to scalable configurations of entanglement distribution and quantum communication which are very promising “, says García Ripoll, researcher at the Institute of Fundamental Physics of the Spanish National Research Council (CSIC) and co-founder of Inspiration-Q, to the daily El País.
Now, scientists want to increase the number of memory qubits, which will allow for more complex protocols to be run, but also for the technology to be used outside of a lab. Of course, this advance is only a first (small) step towards the deployment of a vast quantum network, which should not see the light of day for at least ten years, but it is not, either, to to take lightly.
If the quantum Internet is still far away, experts are already preparing for the possible dangers it represents. For example, the National Institute of Standards and Technology (NIST), located in the United States, is already working on quantum-strength encryption to prevent future quantum cyberattacks.