Quantum teleportation, so the information will travel (ultra safe) of the future

A team of researchers from the Delft University of Technology, claims to have found a deterministic system to teleport qubits that exploit information between atoms and solid state devices three feet apart from each other

Study just published in Science seems to be a decisive step in the development of quantum networks and quantum computers. It would be well to ultra-secure electronic communication. No thanks to strange algorithms are always ready to be craccati by computer experts ill-intentioned, but thanks to the laws of physics are the promise of quantum networks, networks that exploit the laws of quantum mechanics to signal the presence of spies in the channel in which information travels.

Setting them is a challenge that involves the so-called quantum teleportation, a reality in testing since 1998. But if the experiments to date have focused on long-distance for the most part only photons - particles of light that is not interacting with each other, not can create a system perfectly efficient nor store information locally - a great step forward has just been done by a team of researchers from the Delft University of Technology, led by Ronald Hanson.

It took two chips consist of diamonds, stored liquid helium, at 270 degrees Celsius below zero, and laser beams. But in the end they succeeded. Using gemstones created in a laboratory, Dutch scientists ensure that they were the first to have found a deterministic system to teleport quantum information between atoms and solid-state devices that behave like real hard disk. A perfectly efficient and replicable method that has been tested over a distance of three meters. Against the initial half meter and 88 per cent chance of success achieved by Jen-Wei Pan two years ago. The margin of failure is now equal to zero, and the quality of the data transmitted is around 77 percent.

The result of the study just published in Science seems to pose a decisive issue for the possible development of a practical quantum networks, but also of quantum computers: futuristic cars that exploiting the rules of mechanics theorized in the early twentieth century, such as overlapping and correlation of states, will be able to have the exceptional computational capabilities.

"The group Hanson - comment on Repubblica.it Alberto Peruzzo and Alberto Politi, two of the Italians who in 2012 created the first processor can work on quantum states - has shown that this type of teleportation is possible with one hundred percent efficiency. Therefore, while up to now have been made demonstrations probabilistic, ie patterns that work a fraction of the time, hence the method always works. The result is a new step towards the construction of new computing and communication devices based on quantum bits ".

It's not Star Trek. Quantum teleportation is very far from the imaginary created by science fiction. Forget that dematerialize objects suddenly from the desk, only to reappear on the other side of the world. Instead, there is a passage of quantum information from one physical system to another. All without moving the material which they are linked. Explain Cristian Bonato, thirty-four Paduan researcher at Delft, was not involved in the experiment: "This type of information does not take advantage of the classical bits, which can take two binary states: O and 1., But the so-called quantum bits, in accordance with the principle of quantum superposition, can be 1 and 0 at the same time. quantum bits I also have another ability: that of being transferred from one particle to another by using the teleportation is possible due to a unique property of quantum mechanics. "

The principle in question is called entanglement, a sort of mysterious "braiding", whereby two particles once they have come into contact with each other, remain connected even when they are separated and placed at a great distance, for example, one on the ground and the 'other on the moon. Taking advantage of this correlation, a measure of the state of one automatically implies a change in the opposite state of the other. An intuitive phenomenon that does not exist in classical physics and did little to Albert Einstein. A "scary effect at a distance," was the definition used by the genius of physics in a letter to Max Born, who had led even to doubt the validity of quantum mechanics.

Einstein was wrong? "According to Einstein - continues Bonato - the laws of quantum mechanics were so strange that it is not plausible. Physicist believed that the anomaly was due to the fact that we do not have sufficient knowledge to identify the true laws existing in nature because there are hidden variables which we have access. " It all comes down to 1964, when the physicist John Stewart Bell proposed an experiment can distinguish between quantum mechanics and theories of "hidden variables", based on the correlation between how many. The next step for researchers will try the experiment at a mile and a half away, in August. "By increasing the distance between the particles, we can guarantee that does not have time to communicate with each other in any way possible because signals can only propagate at the speed of light. Way we can definitely check out the concept of entanglement and close the debate about whether that quantum mechanics is the correct and necessary description of reality or not.'ll find out soon whether Einstein was right or wrong. "

The experiment details. More in detail, the team led by Hanson has used the same defects that characterize the color of the diamond, where one of the carbon atoms is missing and another is replaced by a nitrogen atom. The first step was to create the entanglement between two individual electrons in the two chips stored in two cryostats containing liquid helium, used to maintain the temperature to about 270 degrees below zero. "Once prepared the nodes of the network and the quantum channel through a complex sequence of laser pulses, microwave and radiofrequency, my colleagues have teleported the quantum state of the nucleus of nitrogen content in a diamond in the single electron present in the other diamond, place three meters away. Transferring the same procedure much more chip away it's just a matter of engineering-type. Will be linked by a mile of optical fiber, but the basic principle is the same. "

Secure network and quantum computers: practical applications and limitations. The most immediate way in which you can take advantage of this new result will be the creation of a quantum network. "In such networks, the information will be encoded on single photons and stored in local nodes consisting of, for example, by single electrons and nuclei in the diamond. Has the advantage that structures are basically safe for the Heisenberg uncertainty principle: simplifying, it is not can simultaneously learn two characteristics of a quantum object. therefore any attempt to introduce the so-called espionage and disruption would be easily detectable. teleportation protocol, shown in Delft, allowing just transfer quantum information from one node to another network, maintaining the ability to detect the intrusion of lights in the channel. "

But the creation of a quantum network is far away. "This is still an experimental phase physics," says Bonato. "We're not close to a salable product. True, the method of teleportation works deterministically., But only every time the channel is in the entangled state. Precisely the preparation of entanglement is the bottleneck of the system: for now we can achieve about once every minute. course, can be improved: at the moment we are working on optical cavities that should make it easier for the coupling between electrons and photons in diamond, thus allowing us to reach a higher speed. Not to speak of the fact that many, though full of potential, they are also extremely fragile. therefore marketing is still not expected and did not speak before ten years. "