Rather than focusing on the macro picture of what quantum mechanics “really” is, scientists at the Canadian Institute for Advanced Research (CIFAR) wanted to gain a different perspective on a classic experiment to perhaps shape better intuitions.
Researchers demonstrate that particles at the quantum level can in fact be seen as having real-trajectories, rather than just the probabilistic smears that the standard interpretation of quantum mechanics suggests. Scientists recreated the famous double-slit experiment and used a novel new technique to measure the trajectories of photons. The findings were published in the journal Science Advances.
“I’m less interested in focusing on the philosophical question of what’s ‘really’ out there. I think the fruitful question 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,” said team member Aephraim Steinberg at CIFAR.
The standard interpretation of quantum mechanics adheres to the uncertainty principal, which tells us that we can never really know a particles position/ trajectory with complete certainty. Even if we tried to measure a trajectory, the particles mysteriously “collapse” into a particle location, disturbing the system.
In order to measure the photons trajectories in the double-slit experiment, scientists subjected many identical particles to very weak measurements that barely disturbed it, avoiding a collapse. After analyzing and averaging the data, the method showed trajectories that looked similar to classical ones, like those of balls flying through the air.
However, criticism of the technique arose when taking into account quantum entanglement. Quantum entanglement states that if two particles are entangled, a measurement of one particle would affect the other. The critics point out that sometimes a measurement of one particle would lead to an incorrect prediction of the trajectory of the entangled particle.
Scientists found out that this incorrect assumption was actually a consequence of where in their course the entangled particles were measured. The fact that entangled particles can influence one another instantaneously adds to the complexity of the trajectories. Researchers used the term “surrealistic trajectories” to describe them, distinguishing them from “realistic trajectories.”
The team doesn’t challenge the standard interpretation of quantum mechanics and agrees it’s consistent with experimental results and evidence. However, scientists suggest it’s likely helpful to visualize real-trajectories, rather than a mathematical probabilistic wave-function. The results seem to support an interpretation of quantum mechanics known as De Broglie-Bohm theory, which says that particles do have real-trajectories that are accompanied by a “pilot wave.”