Network teleportation: the unprecedented achievement of Dutch researchers paving the way for a quantum Internet

Madrid Quantitative Statistics Advance in small giant steps. Small because the achievements involved involve a unique breaking of limitations, but massive because each step opens up a world of endless possibilities. This is the state of the research he led Ronald Hansonphysicist QuTech Lab subordinate Delft University (Netherlands) who achieved -according to After this Wednesday temper nature– Teleport quantum information Through a primitive network without a direct connection between the sender and receiver. Basic teleportation has already been achieved (Hanson et al.’s team has already shown it), but only between two points, called Alice s Bob, or between adjacent nodes. Now join this pair Charlie from a distance. The three form the first network which, although primitive, allows us to think of a quantum internetwith infinite computing possibilities and observing a hitherto unknown world.

Roland Hanson details the importance of this Quantum Primary Network: “For quantum communication, our work demonstrates how technology can be used instant transfer In a real network environment, with nodes that have no direct connection. In the future quantum internet, this teleportation will be the main method for transmitting quantum information over large distances. Our network can be thought of as a modular quantum computer (where the nodes are the modules); Our work shows that Contract They can exchange quantitative information, even though they are not on a single chip.”

To understand Hanson’s team’s progress, we must start from previous achievements that they themselves shared with other great researchers in this science. The first is to demonstrate that teleportation is possible in the quantum world. Ash Peres (France 1934, Israel 2005) lay the foundations in Physical Review Letters in 1993. Then a journalist asked him: “In the case of teleportation of a person, will the body pass before the soul?” The physicist replied: “Not the body, but only the soul.”

This anecdote is important to understand Quantum teleportation, where the substance is not transmitted through a medium, but the information that imparts its properties. As Hanson explains: “The main feature of quantum teleportation is that the quantum information itself is transmitted at a distance: it does not travel through space or through fibers. The entangled pair (entangledIn English) from qubitwhich is the resource to implement teleportation (“teleporter”), is prepared using a signal over the fibers. Another term has been coined for this phenomenon Albert Einstein When you present this possibility In 1935 with Boris Podolsky and Nathan Rosenin what is called the EPR paradox:remote work scary“.

In this way, when a particle is previously entangled with another, both particles cease to be individual particles with their own specific states and become a system with a single wave function. Any measurement that occurs on Alice is immediately repeated on Bob. This is how Hanson explains: “Measuring one, on the spot, also causes the other to choose a state; in a sense, measuring one also measures the other. This is very different from manipulation of qubit: If we spin Alice, nothing will happen to Bob. So, ghostly work remotely [que planteó Einstein] Refers only to instant link in the measurement results. If things other than the measurement were also transmitted instantly, it would indeed be possible to send messages faster than the speed of light. “

Teleportation has been tested for a quarter of a century, from photons to the most complex atoms and systems. five years ago, Jian Wei Panthe leading researcher in this field working for University of Science and Technology of ChinaWith his team, he was able to teleport photons from the Earth to the satellite Messiusin orbit at an altitude of 1400 km.

Jian-Wei Pan himself explained to this paper how these achievements, fundamental to quantum computing, face a “tremendous challenge”: the existence of noise and defects. “We need to use quantum error correction and fault-tolerant processes to overcome noise and scale the system,” he says.

If the presence of noise and defects can cause the quantum process to fail in a single computer under laboratory conditions, then the problem is compounded in Network operation. This was the great achievement of Hanson’s team: efficient quantum transport between non-adjacent nodes in the network.

In this sense, the Dutch researcher explains: “Noise and defects are a challenge for quantum information processing. In a quantum network, sending information through nodes can lead down the interfering fibers, but this would make the quantum information vulnerable to fiber channel noise and losses. Alternatively, then instant transfer It allows quantum information to be transmitted between remote nodes without suffering from these noise sources. Teleportation required tangle as a supplier. Bob helps create this tangle between Alice and Charlie, who do not share direct physical contact. “

The process continued Previous research where Hanson got a network to work between neighboring nodes. The challenge was to add a third node and create a state between the three that would appear Quantitative correlations.

In the new experience, Alice s Charlie They do not have direct contact with each other, but they are both connected Bob. Alice’s and Bob’s processors set up the process by creating a meshed state between their processors, and Bob stores it while creating a meshed state with Charlie. Hanson summarizes: “After establishing a mesh state between Alice and Charlie, the state to be teleported is created and then executed.” “What happens next is something that is only possible in the quantum world: as a result of the measurement, the information disappears from Charlie’s side and immediately appears on Alice’s side,” he explains. Dutch University.

Juan Jose Garcia Ripolla research scientist in Institute of Fundamental Physics of the Supreme Council for Scientific Research (CSIC) and co-founder of Inspiration-Q, Hanson and his team’s work is very relevant: “It’s a very complex experiment that demonstrates all the principles needed to create quantum communication networks.”

For García Ripoll, who was not involved in the Dutch study, “Sending not only classical information (bits) but also quantum states requires a mechanism that allows the distribution of tangled case Between two remote points and a quantum memory that allows the information to be transmitted while creating this communication channel on the basis of entanglement, it is possible.”

In Hanson’s experiment, NV . centers“a type of diamond inclusion that functions,” explains the Spanish scientist, “like a qubit and can be optically manipulated. This qubit, through the emission of Photonsallows you to create long-distance entanglement.” NV-center is a defect where a carbon atom In the diamond crystal lattice it is replaced by a nitrogen atom (n) and Vacant adjacent network site (Fifth).

One NV allows detection of magnetic moment and has wide applications in quantum technology. According to García Ripoll, “The NV or color center can also speak to the magnetic moments of the surrounding atoms and in the experiment [de Hanson] They use this for quantum memory: transfer information from the NV to a file nuclear spin close (in a carbon-13 isotope).” “The information to be transmitted can be kept secure for a long time, freeing the NV to perform the task of establishing a link with another communication node,” he adds.

“Apart from the quality of the experiment, a demonstration of a sophisticated quantum communication setup, with three nodes and a few Algorithms Also very elaborate, it lays the foundations for extending the idea to very promising scalable assemblies for entanglement distribution and quantum communication”, concludes García Ripoll.

to Adam’s hairphysical from Seville University His first measurement of a quantum sequence is recognized as one of the major developments in physics, it is too early to talk about a quantum internet, although the experiment as a teleportation to a new remote node is relevant.

Capello tries to simplify the achievement to explain this: “You have a quantum state in a city that could be Seville and you want to send it to another city, Madrid. You need an entangled state of qubits between Seville and Madrid. This is a standard teleportation protocol. The interesting thing about the experiment is that it doesn’t Entanglement can only be demonstrated at a certain distance. Let’s say, in the example of cities, the distance is 500 km. If you want to send qubits from Seville to San Sebastian, you have to save a file Setting the distance. This is what Hanson described: It is no longer Seville – Madrid, it is Seville – San Sebastian. Double the distance.

“It’s a preliminary overview of what the network could be – summarizing -. In other words, it’s no longer a point to point, but rather more nodes can start to share. But talking about a quantum internet is the promise of a lot. Teleportation of quantum information is very useful and will involve a lot Applications. no doubt”.

By the same token, physicists Oliver Slattery s Young Soo Kim They highlight the progress made by Hanson and his team as an important and “decisive” step in creating the next generation of a quantitative and secure Internet. They also highlight the importance of innovations developed to realize the process: preparation, manipulation, and reading of quantitative states.

However, both physicists point out: “Further improvements to multiple system features will be needed to enable Multiple rounds of teleportation It produces large-scale quantum networks.”

By Raoul Lemon