Quantum physics is so strange that we need imaginary experiments with hidden cats in boxes and coin-flipping metaphors to even begin to grasp its laws. But even in our classical world, where physics is more intuitive, shades of quantum behavior can be represented using relatively simple scenarios.

By experimenting with small oil droplets flowing through two adjacent channels in a vibrating liquid bath, the researchers discovered that the droplets’ behavior matched a well-known quantum experiment.

“This hydrodynamic pilot wave experiment reveals many properties of quantum systems previously thought impossible to understand from a classical perspective,” says John Bush, an expert in fluid dynamics at the Massachusetts Institute of Technology (MIT).

By simulating the Elitzur-Weidman bomb tester (a well-known example), Bush and his colleague, MIT physicist Valerie Frumkin, were able to obtain details of the quantum state of one object by flicking another object’s wave without disrupting its gentle nature. measurement without interaction.

This approach has been applied to low-intensity imaging technology, but despite its use there is no consensus on what ‘free interaction’ means physically.

In an experiment with a bomb tester, a photon splits into two states simultaneously (superposition). These two states pass through one of two channels, and half the time a ‘bomb’ is found in one of these channels; This is an analogy of an object that can destroy superposition by absorbing a photon and destroying its own quantum state in the process.

If the photon leaves the system, it most likely did not collide with a bomb. The magic of quantum physics is that the state of the split photon when it recombines into a single whole can tell us whether there is a bomb or not, even without ‘detonating’ the bomb – even if the photon has entered a different channel.

It doesn’t make sense in terms of classical physics, but that’s why we have quantum physics. In general, the bomb interferes with the possibilities that superposition creates for the photon. This interference can be detected when the wave-like nature of the photon is measured at the tip. It is therefore surprising to find the same result in this study in a classical setting.

Droplets replaced photons, and the liquid ripples they created acted as superposition possibilities; If these expanding ripples hit the bomb, they affected the droplet due to the recombination of the two channels, even though the droplet occupied another channel.

Technically, this experiment has more in common with an interpretation of quantum experiments called pilot wave theory, in which interacting waves carry tiny particles to control the properties of an object.

Statistically, the classic experiment matched the Elitzur-Weidman bomb tester. Researchers say this shows there is a bridge between the fixed, hard world of classical physics and the fuzzier, less precise quantum world. This helps us better understand why quantum behavior, such as probability waves, “collapses” into discrete states.

“Here we have a classical system that gives the same statistics used when testing the quantum bomb, which is considered one of the wonders of the quantum world,” says Bush. “We actually found that this phenomenon is not that remarkable. This is another example of quantum behavior that can be understood in terms of local realism.”