Quantum physics is fundamentally strange, so we need thought experiments with hidden cats in boxes and metaphors of spinning coins to even begin to understand its laws.
Even in our classical world, where physics is more intuitive, shades of quantum behavior can be represented using relatively simple scenarios.
Researchers experimenting with small oil droplets flowing in two adjacent channels in a bath of vibrating fluid discovered that the behavior of the droplets was consistent with a famous quantum thought experiment.
“It turns out that this hydrodynamic pilot-wave experiment shows many aspects of quantum systems that were previously thought to be impossible to understand from a classical perspective,” said John Bush, a fluid dynamicist at the Massachusetts Institute of Technology. of Technology (MIT).
Bush and his colleague, MIT physicist Valeri Frumkin, simulated the Elitzur-Vaidman bomb tester, a well-known example of non-interaction measurements capable of extracting details of an object’s quantum state using mild caressing the wave of another object without disturbing the delicate nature of either of them. .
The method is applied to low-intensity imaging technology, despite its uses, there is no consensus on what the physical meaning of ‘interaction free’ is.
In the bomb tester experiment, a photon splits into two states at once (a superposition). Those two states travel in one of the two channels, and half the time, one of the channels has a ‘bomb’ in it an analogy for something that destroys the superposition by absorbing a photon and has its own quantum state destroyed in the process.
If a photon exits the system, it probably hasn’t hit any of the bombs. Now the magic of quantum physics is that the state of the split photon when it is recombined into a whole can also tell us whether the bomb was there or not even when the photon took the other one. channel without ever ‘detonating’ the bomb.
It doesn’t make sense from a classical physics perspective, but that’s why we have quantum physics. In basic terms, the bomb disrupts the probabilities created by the superposition for the photon. That interference can be detected when the photon’s wave-like behavior is finally measured.
It is therefore surprising to find similar results in this study in a classical setup.
The droplets replace the photons, and the liquid ripples they create act like superposition probabilities. took the other channel himself.
Technically, the experiment has more in common with an interpretation of quantum experiments called pilot-wave theory, where the interacting ripples that carry the small surfing particles guide the characteristics of an object.
Statistically, the classical experiment is consistent with the Elitzur-Vaidman bomb tester. The researchers say it represents a bridge between the fixed, stable world of classical physics and the fuzzier, less specific quantum realm.
This helps us better understand why quantum behaviors such as probability waves appear to ‘collapse’ into discrete states.
“Here we have a classical system that gives the same statistics that appeared in the quantum bomb test, which is considered one of the wonders of the quantum world,” Bush said.
“Actually, we realized that the phenomenon was not so strange after all. And this is another example of quantum behavior that can be understood from a local realistic perspective.”
The research was published in Physical Review A.
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