Researchers at TU Delft there are, together with colleagues from England and Spain , first succeeded in demonstrating empirically that quantum entanglement exists. Quantum Entanglement is counter-intuitive phenomenon that two quantum particles to exhibit together related behavior, or in terms of quantum computing: show a complementary qubit value
<. <- - end of intro text!>! – Highlight -> The phenomenon was already known and also used for communication in laboratory setting up to establish which is impossible to intercept, as the information is transmitted from A to B without passing through intermediate points. On theoretical grounds, the assumption here was not only that the “entanglement” to intercept and route it is impossible but that it takes place immediately (without the passage of time). The latter was so far never really been demonstrated experimentally.
Although the quantum theory it predicted met with the idea that the detection of an object (in particular the read-out of qubit) immediately have an effect on a different object, even if it is located on the other side of the Milky Way, for a long time on great resistance. Albert Einstein for example, refused to accept such a “spooky action at a distance ‘. Together with the physicists Podolsky and Rosen, he suggested in a famous article, known as the ‘EPR’-paper, that quantum mechanics admittedly had proven merits, but because of the strange prediction of entanglement no complete theory could be.
Diamond
Eighty years later shows a team of scientists, led by Ronald Hanson from TU Delft, shows that Einstein had it wrong. They showed that two entangled electrons in diamond separated by over a kilometer campus together, really can have an immediate connection. The experiment, which she published this week in Nature, shows that the “ghostly effect” is real.
“The Quantum mechanics states that a particle, such as an electron, may be located at the same time in two different states. It may even be in two different places at the same time, as long as it is not observed. This phenomenon is called “superposition.” It goes completely against our intuition, “says Ronald Hanson. His research group works with ‘spin’, a tiny magnetic effectje of the electron, which can point up or down. It can also both be at the same time, in superposition. “It gets really interesting when we two electrons ‘intertwine’ so that they together form a whole. Then they are both up and down simultaneously, but once we find one perceive and ‘up’, we determine that the other “down” state. That effect is immediate, even if the other electron could be in a rocket on the other side of the galaxy, “said Hanson.
Bell Test
Hanson’s research is a practical implementation of a 1964 CERN scientist John Stewart Bell thought experiment: the Bell Test. This experiment performs a smart way measurements on the two sides of an entangled pair and exclude the other explanations are suggested by Einstein (‘hidden variables’) off. During the last four decades, many scientists carried out tests Bell, with results showing that the spooky action at a distance indeed existed. But every Bell test contained far back doors, so-called “loopholes”, which nevertheless could not be entirely ruled out that Einstein may be right.
For example, it might be, if the particles are too close to each other, that there is communication between them during the experiment (the “locality loop hole”) so that the observed correlations with a local model can be explained. A second back occurs when the experiment only a small part of can truly measure the entangled pairs. Then is it possible that the observed part is not representative of all entangled pairs: the “detection loophole. The back doors open to explanations without “ghostly influences” are not excluded.
Faster than light
The merit that Hanson and his fellow researchers now claim, is that they are the first to have passed all the loopholes to close concurrently ” We have two laboratories, one in the physics building and one in the Reactor Institute on the other side of the campus. The large distance between the assemblies ensures that neither the detector nor the electrons themselves may exchange information with each other during the experiment. This exchange can never go faster than the speed of light and the distance between the labs is simply too big to bridge in the time that we need to measure the electrons, “says PhD student Bas Hensen, lead author of the publication in Nature . “This is the lokaliteits-loophole poem. We also exclude the detection loophole, because we detect all entangled pairs in our experiment. It is the first Bell Test free of loopholes, and we still see that the invisible and immediate connection of entanglement is real: the ghostly influences are real “.
Security Key
The Delft experiment closes a chapter of one of the most intriguing debates in science, once started among the greats Albert Einstein and Niels Bohr. But the experiment also has an important application: entanglement makes a kind of inherent secure communication. The results of the measurements are also used as a security key. It is fundamentally impossible for hackers to eavesdrop on the key because the key does not travel between two points, but is created out of the entanglement. At least, if there are no loopholes, because they are back doors through which hackers could still sneak in. Quantum mechanics can only make an inherently safe form of communication if all loopholes are closed. The Delft experiment for the first time demonstrated that the loopholes can be all closed.
No comments:
Post a Comment