Science fiction or near future? You wonder trends all summer long. This week we explore just how realistic teleportation can be. A form of teleportation does exist, but moving people at the speed of light will forever be a utopia. What appears to be a well-established navigation tool in science fiction is still woven into the small world of quantum theory.
Harry Potter and Star Trek fans will always dream about it. Potter and his friends can navigate the magic of “Phenomena”, while in the world of Captain James T. Spock uses a machine to break down the DNA of a crew member to put it back together elsewhere as if the distance didn’t exist.
Harry Potter and Star Trek fans will always dream about it. Potter and his friends can navigate the magic of “Phenomena”, while in the world of Captain James T. Spock uses a machine to break down the DNA of a crew member to put it back together elsewhere as if the distance didn’t exist. Although teleportation may seem unlikely, a number of experiments have been conducted in the last quarter of a century which seem to indicate that this phenomenon is approaching. In 1998, Professor Anton Zeilinger at the University of Vienna succeeded in moving a photon from one bank of the Danube to the other. Twenty years later, a research group from the QuTech Laboratory at Delft University of Technology (TU Delft) conducted an experiment that once again confirmed that it is possible to teleport quantum information. They can entangle two separate electrons that share each other’s properties. Have the first steps towards teleportation been taken? Teleportation, as seen in science fiction, begins with the idea that it is possible to collect all the information about an object down to the subatomic level, transmit that information faster than light and reconstruct the object somewhere else. “But in quantum theory, it’s a fundamental law that you can’t move particles faster than light,” says Frank Verstreet, professor of physics at Ghent University. Word fell: quantum theory. You need it to describe the world at the subatomic level. In order to make teleportation possible, an object – or a person – must be decoded to this level. Only in this field of physics do so many seemingly counter-intuitive laws appear that almost quantum theory becomes a philosophical discipline. In fact, quantum physics is a kind of probabilistic interpretation of reality, in which every small particle is in a quantum state. This is the wave curve that consists of a set of variables such as position, direction, and speed at which the particle is moving. For teleportation, you have to collect all the information about the object’s quantum state before sending it. However, according to another physical principle, it is impossible to fully determine the quantum state of an object. Physicists refer to the Heisenberg uncertainty relationship for this purpose. As early as 1927, he described that in quantum mechanics there are pairs whose magnitudes cannot be precisely recorded at the same time. In other words: if you determine the position of the particle precisely, then the velocity becomes uncertain. For similarity, think of dice. You have a one in six chance to roll three. But the more likely you are to do the third roll, the less likely you are to roll anything else. In quantum mechanics, it is possible for two particles simultaneously to have many seemingly mutually exclusive properties. For example, qubits, which are quantum versions of classical zeros and others for digital information, can be both zero and one at the same time. If you transfer this thought from the subatomic level to the sensory world, you reach Schrödinger’s cat. In that 1935 thought experiment, a cat was locked in a box containing a radioactive atom, a Geiger counter, and a bottle of hydrocyanic acid. When the atom decomposes, the Geiger counter hits and the bottle of hydrocyanic acid breaks. In this case, the cat dies. If it does not expire, the cat will live. In quantum theory, a cat can be alive and dead at the same time, as long as you don’t open the box to see if the atom has eroded. For Schrödinger, this experiment was enough to conclude that quantum mechanics was just a theoretical model, but not a description of the real world, where a cat cannot be alive and dead at the same time. Quantum theory proves useful in understanding small particles in physics. And we now have the tools to do experiments at the atomic level and see things that Schrödinger thought impossible. For example, experiments at Delft have shown that you can transmit information about the position and direction of an electron via teleportation without changing it. “We did it without moving the electron itself,” says Levine Vandersiben, Flemish scientific director of QuTech in Delft, the Institute of Quantum Technology at TU Delft and the Dutch Organization for Applied Scientific Research TNO. “In our experiments with teleportation of quantum information, an electron is present in both places. We are only transmitting information about the state of the electron.” This is not easy. This requires the two electrons to be entangled first. The bottom line is that with two entangled electrons on one side a change in information occurs, but also instantaneously with the electron on the other side. This is a multi-layered link. Suppose you toss a coin and write the result on two pieces of paper. You send one to someone in New York and the other to someone in Los Angeles. Nobody can know what is in those envelopes, but if the result is in one coin, it will be the same with the other. Entanglement first appeared in a paper by Albert Einstein in the 1930s. He saw in it evidence that quantum mechanics is incomplete. According to him, there must be ghostly forces at work that can make two molecules in different places so closely related, that they share all their properties. By illuminating two electrons with the same laser beam and entangling them with the emitted light, the Delft researchers showed that entanglement is indeed possible. In 2014 they did it at a distance of 3 metres, four years later at a distance of 1.3 kilometres. QuTech’s test is a step toward transmitting quantum information over great distances. Through an optical cable it becomes possible to transmit information at the speed of light. But if high-speed internet is the only advantage, does teleportation make sense? “There are certainly useful applications for that insight,” Vandersypen says. “Here at Delft we’re working on a quantum version of the internet. It’s not just about speed, it’s also about security. No one can listen or make a change unnoticed. Because if someone tries to intercept a photon, it affects the quantum state. And it’s observed. “. Is an alternative to blockchain technology more suitable than a future application in space travel? Vandersypen: “You can see a parallel with blockchain technology, both of which increase the security of cryptography. But the difference is that blockchain starts from the assumption that the most powerful computers cannot crack the key, while the quantum version relies on the natural laws to ensure security. The quantum Internet is Simply impenetrable to hackers.”
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