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The famous double-slit experiment, in time rather than space


image courtesy https://www.imperial.ac.uk/


We are all familiar with the double-slit experiment which goes to prove the dual nature of light showing that light can behave either as a particle or as a wave.


We are also familiar with the space-time concept made familiar to us by Einstein’s famous theory of relativity.


In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur.



Well, what if we could apply these two concepts together to explore the nature of light further? Will light behave as a particle as well as a wave in the fourth dimension of time as well?


This is exactly what physicists at the Imperial College London have been able to demonstrate experimentally. They have achieved a significant milestone in the world of quantum physics by recreating the famous double-slit experiment in time rather than space.


The groundbreaking experiment, led by Professor Riccardo Sapienza of the Department of Physics at Imperial College London, involves firing light through a material that changes its optical properties in femtoseconds, allowing light to pass through at specific times in quick succession.


The team’s achievement opens the door to a whole new spectroscopy capable of resolving the temporal structure of a light pulse on the scale of one period of the radiation.


The original double-slit experiment, performed in 1801 by Thomas Young at the Royal Institution, showed that light acts as a wave. Further experiments revealed that light behaves both as a wave and as particles, exposing its quantum nature. These experiments had a profound impact on quantum physics, revealing the dual particle and wave nature of not just light, but other “particles” including electrons, neutrons, and whole atoms.


In the classic version of the double-slit experiment, light emerging from the physical slits changes its direction, so the interference pattern is written in the angular profile of the light. The Imperial team’s experiment, however, changes the frequency of the light rather than its direction, altering its color and creating colors of light that interfere with each other to produce an interference-type pattern.



The material used in the experiment was a thin film of indium-tin-oxide, the same material used to make most mobile phone screens. The team used lasers on ultrafast timescales to change the reflectance of the material, creating the “slits” for light. The material’s response was much quicker than the team expected, varying its reflectivity in a few femtoseconds.


Overall, the Imperial team’s achievement is a significant milestone in the field of quantum physics, providing deeper insights into the nature of light and opening the door to the development of new technologies that could transform our world. With further research, it is likely that metamaterials will become increasingly important in a wide range of industries, leading to new advancements and discoveries that we can only begin to imagine.

web site: https://www.imperial.ac.uk/

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