Imperial physicists have recreated the famous double-slit experiment, which showed that light behaves like particles and waves in time, not space. In a groundbreaking development, physicists at Imperial College London have recreated the historic double-slit experiment, which showed that light behaves like a particle and a wave in time, not space. Using materials that can change their optical properties in femtoseconds, the team successfully passed light through a thin film of indium oxide and tin, creating temporary “slits” for light to pass through. The experiment not only provides insight into the fundamental nature of light, but also serves as a stepping stone to the development of advanced materials for controlling light, both in space and time. These materials could potentially contribute to the development of new technologies and aid the study of fundamental physical phenomena such as black holes.

The experiment relies on materials that can change their optical properties in fractions of a second, which can be used in new technologies or to probe fundamental questions in physics. The original double-slit experiment, performed at the Royal Institution by Thomas Young in 1801, showed that light behaved like a wave. However, further experiments showed that light actually behaves like a wave and particles, revealing its quantum nature.

These experiments had a profound impact on quantum physics, revealing the binary particle-wave nature of not only light but also other “particles” including electrons, neutrons, and whole atoms.

Now a team led by physicists at Imperial College London has conducted an experiment using “gaps” in time instead of space. They achieved this by passing a material that changes its properties in femtoseconds (quadrillions of a second) and allowing light to pass quickly through it only at certain times.

Professor Riccardo Sapienza, principal investigator in Imperial University’s Department of Physics, said: “Our experiment reveals more about the fundamental nature of light, while also providing a springboard to the creation of cutting-edge materials that can precisely control light both in space and time.” “

The original two-slit setup involved directing light onto an opaque screen with two thin, parallel slits. Behind the screen was a light detector passing through it.

To pass through the slits as a wave, the light splits into two waves that pass through each slit. When these waves intersect again on the other side, they “interfere” with each other. Where the crests of a wave meet, they reinforce each other, but where the crest and trough meet, they cancel each other out. This creates a banded pattern on the detector that receives more or less light.

Light can also be split into “particles” called photons, which can be recorded as they strike the detector one by one, gradually creating a striated interference pattern. Even when the researchers fired only one photon at a time, the interference pattern continued to appear as if the photon had split in half and passed through both slits.

In the classical version of the experiment, the light coming out of the physical slits changes direction, so the interference pattern is recorded in the angular profile of the light. Instead, the time intervals in the new experiment change the frequency of the light, which changes its color. This created light colors that interact with each other, amplifying and canceling certain colors, forming an interference-type pattern.