For physicists, the double slit experiment is somewhat mythical. And it is this myth that researchers are now proposing to us to revisit. By no longer intervening in the path of light in space, but… in time!
The double slit experience. It’s a bit of a mythical experience. Some do not hesitate, moreover, to present it as the most beautiful of all. An experiment by which the genius physicist Thomas Young (1773-1829) demonstrated, in 1801, the wave nature of light. Direct a beam on a double slit and you will indeed observe, on a screen placed behind, an alternation of lit zones and unlit zones. Interference fringes, as researchers call them. Which, according to classical physics, can only be explained by phenomena of interaction, of interference between light waves which are reinforced when their peaks meet and cancel each other out when, on the contrary, their troughs cross.
Other experiments have shown that light is more than that. It also exhibits particle properties. Hence the consecrated expression of physicists to describe it as wave-particle duality. And the fact that it is now considered a quantum object. This is also the case for other “particles” like electrons or neutrons.
Of the researchers of theImperial College London (United Kingdom) were inspired by the unique experience of the double slit to go even further in their description and their mastery of light. They imagined an experience of the double slit no longer in space, but in time!
Temporal interferences
To create their double time slit, the physicists used a relatively standard material. A thin film of indium tin oxide. The kind that makes up most smartphone screens today. And using high-powered, ultra-fast infrared lasers, they changed the reflectance of this film on time scales of the order of a femtosecond – or 10-15 second. Thus opening up “time slots” for the light.
In the classic version of the double slit experiment, the light changes direction as it passes through the “space slots”. Passing through time slots, created here by physicists, has another effect on light. He makes her change frequency. Change color, then. What finally also form an interference-type pattern from the interactions, this time, between colors that reinforce or cancel each other out.
The physicists of theImperial College London now hope to be able to put their observations to good use. By combining the extremely fine temporal control of light they achieved with spatial control, they might be able to develop new cutting-edge technologies. Even to study fundamental physical phenomena such as black holes in a new way. The researchers particularly want to explore the phenomenon in what they call temporal crystals – analogues of classical crystals, but whose optical properties, instead of varying in space, vary over time. Hoping to develop ultra-fast, parallelized optical switches, for example.
