It was 1935 and Erwin Schrödinger was already tired of reading nonsense. It was not a decade since the birth of modern quantum mechanics, but the world had already filled with delusional pseudophilosophical reflections on what reality really was.
It was then that poor Erwin inflated his noses and decided to talk to us about his cat.
The happy cat of Schrödinger. Of his cat, of a closed opaque box and, in addition, of a container with a poisonous gas. The container in question is controlled by an opening device that only works if a radioactive particle disintegrates over a certain period of time.
After that period, the probability that the cat is dead is 50% and that it is also alive of 50%. “If we do not open the box,” the standard version of this ‘paradox’ tells us, “the cat will be alive and dead at the same time.” Or, in other words, we could be calm: as long as we did not open the box, the cat would not be really dead.
According to many interpreters, in fact, it would be the one that opens the box that kills the cat.
No one understands poor Erwin. The interesting thing about all this is that, although it has been used to the fed up to illustrate The idea of quantum overlapSchrödinger used it to demonstrate how absurd it was to apply categories of quantum mechanics to the real world (macroscopic). For the Austrian physicist, the happy cat would be alive or dead regardless of the opening of the box or not.
But … what if not? However, half a century after all this, there were a group of researchers from the University of Berkeley who did not have it so clear. For some years it was known that we were missing a key piece to understand the process of molecular disintegration.
That is, “the ability of individual particles to disintegrate is well known” (this is, for example, the physical fact that there is Behind carbon-14); What happens is that according to what we knew about physics, that could not be. The particles should not disintegrate.
Between 1984 and 1985, John Clarke, Michel H. Devoret and John M. Martinis They performed a series of experiments With a closed electrical circuit with superconductors and showed that, well, Schrödinger was wrong.
How was it wrong? As I say, the intention of the cat’s mental experiment was “to demonstrate the absurdity of this situation, since the special properties of quantum mechanics usually disappear on a macroscopic scale. The quantum properties of a complete cat cannot be demonstrated in a laboratory experiment.”
However, since these researchers were successful in demonstrating that the very strange properties of the quantum world can also be seen in a larger system, none of this is so clear.
This explains very well people like Anthony Leggett Because, although “a macroscopic system composed of numerous pairs of Cooper remains many orders of magnitude smaller than a kitten”, the key of the experiment is that “there are phenomena that involve a large number of particles that, together, behave as they predict quantum mechanics.”
A Nobel to kill a cat. “It would surprise you very much if the ball suddenly appeared on the other side of the wall. In quantum mechanics, this type of phenomenon is called a tunnel effect and is precisely the type of phenomenon that has given it the reputation of being strange and not very intuitive,” explained the award committee. That is precisely what these researchers showed that it could happen at the macroscopic level.
But they did something else. And I do not mean to lay the foundations that have allowed us to create the technological system we know: from the transistors of the computer microchips that we see everywhere to quantum cryptography. No. I mean blurring the wall that separated the world from the very small with the world we know.
Along the way, “they killed a cat”; But because of the gap they opened, one of the best science we have was sneaked.
Image | Nobel Foundation
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