Schrödinger's cat retained superposition after cutting into two boxes

Scientists from Yale University have taught a small lesson in quantum magic with the help of a new version of Erwin Schrödinger's famous mental experiment with a cat that is in quantum superposition , that is, in two states at the same time. This is quite a common state of quantum particles, for example, photons. The superposition is maintained until a measurement is made, after which the photon selects one of two possible states.

Now physicists have taken the experiment to a new level . Scientists have cut an imaginary cat into two halves (Alice and Bob) and put them in two boxes. The experiment was carried out in real laboratory conditions. The role of Schrodinger's cat played electromagnetic waves.

During the experiment, two aluminum boxes were designed for electromagnetic particles - microwave resonators, inside which photons can exist only at certain wavelengths. The resonators are interconnected by a channel from a superconducting sapphire chip and an aluminum conductor through which an electrical signal passes.
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The essence of the experiment is that “intricate” photons were launched into the resonators, that is, photons interconnected at the quantum level. Physicists have determined that the confusion of photons really remains in the boxes. That is, if in the first box the photon assumed a certain state, then the photon associated with it in the second box has the opposite state. In other words, at the connected photons at each instant of time two opposite states, as at Schrodinger's cat.

“The mechanical counterpart of this could be a pendulum that moves left and right at the same time,” explained Chen Wang, one of the authors of the scientific work.



To prove the confusion of photons without measuring their state, physicists counted the number of photons in each box, writes New Scientist. In each of them, sometimes there was an even number of photons, and sometimes an odd number, but the sum was always even, which corresponds to the integral state of the Schrödinger cat.

Thus, Schrödinger's cat and quantum entanglement are really preserved when divided into two halves - this is a key principle in the technology of creating quantum computers.

The scientific work was published in the journal Science (doi: 10.1126 / science.aaf2941).