Thursday, September 14, 2017

Exotic Photon Trajectories in Quantum Mechanics

Jim and Randy discuss strange trajectories observed in triple slit experiments with metallic plates. Photons seem to pass through one slit, come back through the middle slit, and out the third due to their interactions with surface plasmons. There are implications in this experiment about the way in which wavefunctions need to be interpreted in non-relativistic quantum mechanics.



1. The paper we read for this program: Exotic looped trajectories of photons in three-slit interference by MagaƱa-Loaiza, et al. [arXiv]

2. Our subreddit.


The following post was made to the arXiv_plue subreddit about this paper:

This paper discusses deviations from the predictions of the Born rule (the interpretation of the probability of an observation being the norm of the convolution of the wave functions of the initial and final states) that are observed when the interference effects of a triple slit experiment are examined. By using a three slit experiment rather than a two slit experiment, the authors follow the procedure of Sinha, et al., that showed a null result in 2010. This procedure looks at all seven combinations of the three slits (in a random order), subtracting the three slit interference pattern from the interference patterns of the other six combinations. The combination of the six double and single slit interference patterns should exactly match the the triple slit interference pattern if the Born rule held.

In 2010, they found that the Born rule held, to one part in 100.

This paper (published in Nature Communications) uses surface plasmons on a gold barrier to "enhance the electromagnetic near-fields" near the slits in a way that increases the likelihood of trajectories that cause violations of the Born rule. These trajectories snake and backtrack through the triple slit apparatus.

The comparisons between the single, double, and triple slit interference patterns indicate evidence for these snaking trajectories. Whether this really indicates evidence that the Born rule fails, I'm not sure.