First-ever experiment proves light travels through both space and time

The team’s achievement opens the door to a whole new spectroscopy capable of resolving the temporal structure of a light

[Aug 5, 2023: Staff Writer, The Brighter Side of News]

Imperial physicists have recreated the famous double-slit experiment, which showed light behaving as particles and a wave, in time rather than space. (CREDIT: ICL)

A remarkable breakthrough has been achieved by physicists from Imperial College London, as they have successfully replicated the renowned double-slit experiment within the dimension of time, rather than space.

This pioneering endeavor, spearheaded by Professor Riccardo Sapienza from the Department of Physics, Imperial College London, entails directing light through a substance capable of swiftly altering its optical characteristics in femtoseconds. This remarkable transformation enables the passage of light to occur during precise time intervals in rapid 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.


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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.

The team’s achievement is published in Nature Physics, with the lead researcher, Professor Sapienza, saying: “Our experiment reveals more about the fundamental nature of light while serving as a stepping-stone to creating the ultimate materials that can minutely control light in both space and time.”

The famous double-slit experiment, which showed that light can behave both as a wave and as a particle. (CREDIT: Creative Commons)

Co-author Professor Sir John Pendry also commented on the experiment, saying, “The double time slits experiment 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 team’s experiment holds significant implications for quantum physics and opens the door to the exploration of new technologies that could revolutionize our understanding of the nature of light. Furthermore, the team’s next goal is to explore the phenomenon in a “time crystal,” analogous to an atomic crystal but where the optical properties vary in time. According to co-author Professor Stefan Maier, “The concept of time crystals has the potential to lead to ultrafast, parallelized optical switches.”

Observation of a spectral diffraction pattern from temporal double slits. (CREDIT: Nature Physics)

The Imperial team’s achievement is a groundbreaking milestone in quantum physics, providing deeper insights into the nature of light and opening the door to potential applications with metamaterials providing a new avenue for exploring fundamental physics phenomena like black holes.

In addition to the potential for studying black holes, the team’s work could also have significant implications for the development of new technologies. The ability to minutely control light in both space and time could lead to advancements in fields like telecommunications, computing, and even medicine.

Professor Riccardo Sapienza and Sir John Pendry of the Department of Physics at Imperial College London (CREDIT: ICL)

Telecommunications is one field where the team’s findings could have a significant impact. By controlling the timing and frequency of light, researchers could develop new types of optical switches that are faster and more efficient than current technologies. This could lead to faster internet speeds and more reliable data transmission, among other benefits.

The field of computing could also benefit from the team’s work. By using metamaterials to control the behavior of light, researchers could develop new types of optical processors that are faster and more energy-efficient than current electronic processors. This could lead to the development of computers that are both faster and more energy-efficient, with the potential to revolutionize the field of computing.

Now, a team led by Imperial College London physicists has performed the experiment using ‘slits’ in time rather than space. (CREDIT: ICL)

In medicine, the ability to control the timing and frequency of light could lead to the development of new types of diagnostic and therapeutic tools. For example, researchers could develop new types of imaging technologies that are more precise and less invasive than current techniques. They could also use light to precisely target and destroy cancer cells, leading to more effective cancer treatments with fewer side effects.

The potential applications of the team’s findings are not limited to these fields, however. Metamaterials have the potential to revolutionize a wide range of industries, from energy and transportation to aerospace and defense.

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.


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Joseph Shavit
Joseph ShavitSpace, Technology and Medical News Writer
Joseph Shavit is the head science news writer with a passion for communicating complex scientific discoveries to a broad audience. With a strong background in both science, business, product management, media leadership and entrepreneurship, Joseph possesses the unique ability to bridge the gap between business and technology, making intricate scientific concepts accessible and engaging to readers of all backgrounds.