They show that the teleportation of quantum bits in a network without cables or waves is possible, with a view to a safer internet

As ideal as it sounds, it doesn’t seem physically possible that you can teleport. That you close your eyes, avoid a boarding line, take a flight and appear on the other side of the world. Things don’t go like this for macroscopic objects. The teleportation of particles or molecules has hardly been possible. But in the world of physics of the smallest, what matters is the information. And that’s a little easier to move. Quantum teleportation is possible.

Albert Einstein called it the ‘spooky effect at a distance’. Technically, it is known as ‘quantum entanglement’. A phenomenon that only occurs in the world of the immensely small, of subatomic particles, and is the basis for a possible internet of the future to be hypersecure. Now they have taken a further step in this direction and have achieved the teleportation of a quantum bit of information between two nodes that are not connected to each other.

Objects that share quantum entanglement share properties. What happens to one automatically affects the other, even if they don’t see each other or connect them with any cable or wave. This can be done with particles that contain information, as if they were envelopes with letters. Those letters would be the bits, in digital information, that is, zeros or ones. In the world of quantum computing, bits have an advantage: they can be zeros, ones, or zeros and ones at the same time.

When Charlie’s quantum state was changed, Alice’s state also changed, meaning that the information traveled in quantum teleportation through Bob, but not through him. Compared to the world of TV airwaves, it would be as if Bob were a repeater antenna. But a phantom repeater, which doesn’t even receive or emit signals, is just there on guard duty, in case something happens between Alice and Charlie. With that alone, the signal can already travel.

The new experiment goes a little further, here the phenomenon of ‘entanglement exchange’ has come into play, which is the same as teleportation, but now what is transporta is precisely an intertwined state of two qubits

Thus, “if we entangle node A (Alice) with node B (Bob) and also node B with a third node C (Charlie), the interlacing exchange causes A and C to become intertwined, even though They have never interacted with each other. And, in principle, we could go on like this with any number of nodes. The experimental problem is that quantum entanglement is very fragile, and it is very difficult to carry out this process without losing information”.

A cordless intertwining
In the example of the video that heads this information we have changed the characters a little, to simplify. Usually it is Alice (point A) and Bob (point B) who engage in a ‘conversation’, exchanging information. If Bob – in our example – wants to send an encrypted message to Alice he can use a fiber cable. That is typical of the conventional internet. But quantum information requires, for example, entangled photons of light. If they get lost along the way (something that is very normal in cables), that interlacing is broken.

Quantum teleportation spares us that problem. That photon of light (or whatever particle it is, which will be a messenger) can disappear from one place to appear in another. From Bob’s side to Alice’s side. More precisely, the information that defines the state of that particle, as long as there is entanglement between our characters.

“Like in science fiction movies”
It’s really a teleportation like in science fiction movies. The state, or the information, actually disappears on one side and appears on the other, and because it doesn’t travel through the space in between, [the data] can’t be lost either.

Although the use of quantum entanglement for teleportation has been theoretically possible for decades, it has only been successfully tested here. The qubits at the nodes include ‘memory’, which can hold quantum states for longer periods of time than standard qubits.

This could be interpreted as a first (very preliminary) step towards a quantum communication network. However, it must be taken into account that the great experimental difficulty means that the quality of the information transmission is still very low. This can be measured by calculating the so-called ‘fidelity’ of the transmitted state, that is, the resemblance between the actual final state of the qubit and the state we wanted to transmit.

A quantum internet is not the same as a faster internet. Even though nodes share information (change) instantly.