'Quantum Surrealism' Demonstrated in New Study: It's More Useful Than You Might Think

Scientists have demonstrated "quantum surrealism" for the first time. They've shown that particles at the quantum level can be seen as behaving something like billiard balls rolling along a table, and not merely as the probabilistic smears that the standard interpretation of quantum mechanics suggests.

In this latest study, the researchers conducted a new version of an old experiment. They tracked the trajectories of photons as the particles traced a path through one of two slits and onto a screen. However, the researchers went further and observed the "nonlocal" influence of another photon that the first photon had been entangled with.

So what did they find? The results countered a long-standing criticism of an interpretation of quantum mechanics called the De Broglie-Bohm theory. Detractors of the interpretation had said it fails to explain the behavior of entangled photons realistically. However, the results are important because they give a new way to visualize quantum mechanics that's just as valid as the standard interpretation.

"I'm less interested in focusing on the philosophical question of what's 'really' out there," said Aephraim Steinberg, one of the researchers, in a news release. "I think the more fruitful questions is more down to earth. Rather than thinking about different metaphysical interpretations, I would phrase it in terms of having different pictures. Different pictures can be useful. They can help shape better intuitions."

The standard interpretation of quantum mechanics holds that there's no "real" trajectory between the light source and the screen. The best we can do is calculate a "wave function." But the De Broglie-Bohm theory says that photons do have real trajectories that are guided by a "pilot wave" that accompanies the particle. The wave is still probabilistic, but the particle takes a real trajectory from source to target.

Critics, however, point out that if two particles can be entangled, the measurement of one particle affects the other. In some cases, the measurement of one particle would lead to an incorrect prediction of the trajectory of the entangled particle. This resulted in the term "surreal trajectories."

In this case, the researchers showed that surrealism was a consequence of non-locality, which is that particles were able to influence one another instantaneously at a distance. The "incorrect" predictions of trajectories by the entangled photon were actually a consequence of where in their course the entangled photons were measured.

The findings should help researchers understand quantum physics a bit more. And the interpretation should be helpful in some circumstances to visualize real trajectories.

The findings are published in the journal Science Advances.

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