Physics: The 1801 double slit experiment revisited in 2023
As we all recall from high school physics, in 1801 Thomas Young proved the dual wave-particle nature of light. He shot a beam of light into two narrow slits in a piece of metal and saw an interference pattern. Later, the same thing was observed with electrons, then whole atoms and later still with whole molecules. Light and those other things had both wave and particle properties.
The old-fashioned double slit experiment
Simulation of light wave hitting the double slit
(9 sec. video)
And, as we all know, the double slit experiments like this were a way to use 3-dimensional space to demonstrate the dual wave-particle nature of light and matter, at least on a small scale. Now, using the same material that is in cell phone screens, indium tin oxide (ITO), physics nerds have been able to do a double slit experiment where the slits are in time, not space. The image below helps to visualize what is going on.
A laser pulses to cause the ITO layer to cycle between
being reflective for a short time and then transparent
In the time or temporal double slit variant, a light beam hits a very thin layer of ITO, which can very rapidly go from transparent to reflective opaque when pulsed with light. The changes are driven by oscillating super short laser light pulses that flip the ITO layer from cycles of opaque to transparent in about 10 femtoseconds (fs). One fs is 10x(-15) or 1⁄1 000 000 000 000 000 of a second, i.e., (i) one quadrillionth, or (ii) one millionth of one billionth of a second. In essence, what the nerds did was build and successfully operate the machinery for a temporal double-slit-diffraction experiment. That demonstrated the feasibility of time-modulating materials to control light.
Chief temporal double slit experiment nerd
Romain Tirole at the Imperial College London
messing around with his experiment stuff
To the team’s astonishment, the results of the experiment revealed more oscillations than predicted by existing theories, as well as far sharper observations, which points to “unexpected physics” in the findings, according to the study.
“When we measured the spectra, we were very surprised by how clear they showed up on the detectors,” Tirole said. “How visible these oscillations are depends on how fast we can switch our metasurface on and off [and] this means that the speed at which our metamaterial changes is much faster than what was previously thought and accepted. This is exciting as it implies that new physical mechanisms are still to be uncovered and exploited.”
“In our experiment we show that this wonder material has an even faster switching speed, 10-100 times faster than previously thought, which enables a much stronger control of light,” he also noted.
The breakthrough paves the way toward new research into the enigmatic properties of light, and the many emerging technologies that rely on optical phenomena. Tirole and his colleagues are especially eager to try to repeat the experiment with a time crystal, a very strange quantum system that has revolutionized many fields in physics.
“A double slit experiment is the first brick on the road to more complex temporal modulations, such as the much sought time-crystal where the optical properties are temporally modulated in a periodic fashion,” Tirole concluded. “This could have very important applications for light amplification, light control, for example for computation, and maybe even quantum computation with light.”
This new line of research could turn out to be a very big deal. Once physics nerds get a whiff of possible things like unexpected physics, new physical mechanisms and the capacity to fiddle with very strange quantum systems, they are relentless. My sense of this is that if the complexity of such short time manipulation becomes easier, this line of inquiry ought to bear some important fruit within ~ 3 years. That's pretty quick compared to the pace of research into brains, consciousness and the like.
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