MIT physicists have conducted an idealized version of the double-slit experiment, demonstrating the dual nature of light with atomic-level precision. Their findings, published in *Physical Review Letters*, confirm that light exhibits both particle and wave characteristics, but these properties cannot be observed simultaneously.
The double-slit experiment, first performed by Thomas Young in 1801, traditionally involves shining light through two parallel slits and observing the resulting interference pattern on a distant screen. This pattern suggests that light behaves as a wave. However, when attempts are made to detect which slit the light passes through, the interference pattern disappears, indicating particle-like behavior. This phenomenon has been a central topic in quantum mechanics, highlighting the wave-particle duality of light.
In their recent experiment, the MIT team used individual atoms as slits and weak beams of light to scatter single photons. By preparing the atoms in different quantum states, they were able to modify the information obtained about the photon's path. The researchers found that the more information obtained about the path (i.e., the particle nature) of light, the lower the visibility of the interference pattern. This supports the principles of quantum mechanics, particularly the uncertainty principle, which states that certain pairs of physical properties, like position and momentum, cannot both be precisely known simultaneously.
Additionally, the team explored Einstein's theoretical model involving slits suspended on tiny springs. They discovered that even without a physical support mechanism, the fundamental nature of the wave-particle duality persisted. This finding aligns with the predictions of quantum theory and provides further insight into the behavior of light at the quantum level.
The research was led by Wolfgang Ketterle, the John D. MacArthur Professor of Physics at MIT, and co-authored by Vitaly Fedoseev, Hanzhen Lin, Yu-Kun Lu, Yoo Kyung Lee, and Jiahao Lyu. The study was supported by the National Science Foundation, the U.S. Department of Defense, and the Gordon and Betty Moore Foundation.
This work coincides with the United Nations declaring 2025 as the International Year of Quantum Science and Technology, celebrating the formulation of quantum mechanics 100 years ago. The MIT study not only clarifies a historic scientific debate but also contributes to the ongoing exploration of quantum phenomena and the fundamental nature of reality.