A team of researchers at MIT has performed an experiment that confirms a fundamental principle in quantum mechanics: light behaves as both a wave and a particle. The study, led by Wolfgang Ketterle, used ultracold atoms to demonstrate the double-slit experiment’s results.
The double-slit experiment, first performed by Thomas Young in 1801, demonstrates that light can behave as a wave, producing an interference pattern when passing through two narrow slits. However, this raises a fundamental question: can we observe light behaving as both a wave and a particle at the same time?
Albert Einstein proposed adding a mechanical balance to measure which path a photon took, but Niels Bohr argued that the Heisenberg uncertainty principle would blur any such measurement, preserving the mystery of quantum mechanics. Recent studies have confirmed Bohr’s stance, but this new experiment takes it further by using single atoms and single photons.
The researchers cooled over 10,000 rubidium atoms to near absolute zero and arranged them into a crystal-like grid, with each site roughly 0.00004 inches apart. They then sent in one photon at a time, which scattered off the two adjacent atoms before reaching a camera that recorded interference fringes.
By adjusting the “fuzziness” of the atoms, the team was able to observe both wave-like and particle-like behavior. When the atoms were sharply localized, they produced bright, evenly spaced stripes, hallmarks of wave interference. However, when the fuzziness increased, the stripes dissolved into a speckled blob, revealing particle-like hits instead.
The study’s results confirm Bohr’s quantum view and have implications for fields such as light-based computers, precision sensors, and secure communication channels. The findings also dovetail with recent simulations that reached an identical verdict.
Source: https://www.earth.com/news/light-has-two-identities-that-are-impossible-to-see-at-once-quantum-certainty