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There are experiments that, despite their simplicity, have managed to turn science upside down in a very short period of time. The double slit experiment is one such experiment. When light hits two narrow, parallel slits, it deflects them and creates an interference pattern of dark and light lines on the monitor screen behind them. The English physicist Thomas Young conducted the experiment for the first time in 1801, and his result was considered evidence that light behaves as a wave. A few decades later, when other scientists sent entire particles such as electrons, atoms, or even molecules through the slits instead of light rays, they were surprised to find that these, too, behaved like waves when they passed through the slits. Although common sense would lead one to expect that individual objects would fly through one opening or the other and congregate in two places behind the slits, the interference pattern forms very similar to what Young observed. The so-called wave-particle duality of quantum objects has changed the way we look at the world. It is one of the fundamental statements of quantum mechanics, and the double-slit experiment is now one of the most famous experiments in the history of science.
The nine-person team led by first author Romain Tirol mimicked Young’s double-slit experiment—but instead of spatially separating the slits, the researchers directed light through temporally separated apertures. To do this, they used a type of mirror that can be turned on and off very quickly. They discovered that there was also an interference effect in the time dimension. However, you do not see light or dark lines, rather the light changes its frequency and therefore its color. Although this fact follows well-known physical laws, this is the first time that scientists have succeeded in proving this feat experimentally. What’s more, the experiment produced an unexpected result. …
Did you already know…
Dalibard, J. et al.: Atomic wave diffraction and interference using time slits. Physical Review Letters 77, 1996
Ingeta, N.: 4D optics using time-varying metamaterials. Science 379, 2023
Pendry, J.P. et al.: Control of electromagnetic fields. Science 312, 2006
Sapienza, R. And others: Double-slit temporal diffraction at optical frequencies. Nature Physics 19, 2023
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