Quantum internet: the second quantum revolution

Quantum teleportation allows information to be transmitted between two linked quantum particles regardless of the distance that separates them. Unlike science fiction teleportation, which sends matter from one point in space to another, quantum teleportation sends information.

In late 2021, a team of researchers at NASA’s Jet Propulsion Laboratory managed to teleport a small set of quantum information by transporting qubits—as if they were photons—for 44 kilometers. 90% of the information was preserved. Can you imagine the possibilities?

What is quantum teleportation?
Quantum teleportation is a way of sending information using the technique of quantum entanglement whereby two particles are linked through space. This quantum entanglement, called “spooky action at a distance” by Einstein, is a phenomenon whereby two individual particles act as a single wave system.

This is a bit complicated, but just so we understand each other: what if two minds, instead of acting separately, shared exactly the same thoughts in real time? These two minds could do an interesting experiment: while one of them is sitting in class and listening to a teacher, the other can repeat in another class what the teacher is saying.

This effect goes beyond this walkie-talkie example, because the particles in question, although two, function as one. They behave as if they were the same thing in space. So what is done to one, the other reproduces, and vice versa. They are connected or intertwined.

It is important to note that this transmission of information cannot go faster than the speed of light, which is the maximum speed at which it is possible to transport information through the universe. These correlations mean that when acting on one particle the other (intertwined) imitates that behavior. It is this sending of information through space at the speed of light that is called quantum teleportation.

As we anticipated, a team of researchers has managed to send several qubits of information (quantum bits) from one place in space to another. Sending information 44 kilometers away may not be a relevant milestone —after all, there is a mirror on the Moon on which experiments are carried out daily, and the signal sent from Earth travels 384,400km one way and the same back. back to the speed of light—but it is.

The first key is in the way that information has been sent. On the one hand, it was necessary to unify two particles in the form of quantum entanglement, that is, to work as one; on the other, to transport one of the two particles to 44 kilometers, and, finally, to enable a system that reads the particle from the other side without influencing it with the measurement in the information.

The second key is precisely in that last point, in the very high fidelity with which the information has been sent (and decoded). This aspect is perhaps the most complex of the entire operation. And it is that it is not possible to measure a system without altering it substantially. To see what a particle does, you have to throw photons at it and see how they bounce back. In fact, this is how we humans see: photons of light bouncing off objects that then reach our eye.

Reading the information of the second particle without modifying said information is a logistical challenge. And to do it with a 90% success rate, an impressive achievement of science. Of course, where does this whole experiment lead? What could it be used for?

The Internet works by connecting computers using electrical, radio, or photonic impulses. Although a physicist would express that they are three manifestations of the same mechanical phenomenon, in the field of engineering how it influences a lot. The fastest way to send information over the internet is through optical fiber on which photons of light bounce until they travel through it.

The idea is great, but fiber optics (like copper cables) have limitations and challenges. Every certain distance, for example, a device is needed to read the information, correct the errors and send it back to the next checkpoint. All this is done in fractions of a second, but compared to the speed of light it is slow and has significant errors.