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Revolutionary quantum discovery can make atoms transparent

[May 4, 2023: Staff Writer, The Brighter Side of News]

Artist's visualization of a laser striking atoms in an optical cavity. (CREDIT: Ella Maru Studio)

In a groundbreaking discovery, scientists have observed a new phenomenon dubbed “collectively induced transparency” (CIT), in which groups of atoms suddenly stop reflecting light at specific frequencies. The finding has the potential to expand our understanding of quantum mechanics and help develop more efficient quantum memories.

The research team, led by Caltech’s Andrei Faraon, confined ytterbium atoms inside an optical cavity, a tiny box for light, and blasted them with a laser. As they adjusted the frequency of the laser, they observed a transparency window in which the light passed through the cavity unimpeded.


“We never knew this transparency window existed,” says Faraon, who is also the William L. Valentine Professor of Applied Physics and Electrical Engineering. “Our research has primarily become a journey to find out why.”

An analysis of the transparency window revealed that the phenomenon was the result of interactions in the cavity between groups of atoms and light, similar to destructive interference. The groups of atoms continually absorbed and re-emitted light, which usually resulted in the reflection of the laser’s light. However, at the CIT frequency, a balance was created by the re-emitted light from each of the atoms in a group, resulting in a drop in reflection.


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“An ensemble of atoms strongly coupled to the same optical field can lead to unexpected results,” says co-lead author Mi Lei, a graduate student at Caltech.

The optical resonator, which measures just 20 microns in length and includes features smaller than 1 micron, was fabricated at the Kavli Nanoscience Institute at Caltech.

“Through conventional quantum optics measurement techniques, we found that our system had reached an unexplored regime, revealing new physics,” says graduate student Rikuto Fukumori, co-lead author of the paper.


In addition to the CIT phenomenon, the researchers also observed that the collection of atoms could absorb and emit light from the laser either much faster or much slower than a single atom, depending on the intensity of the laser. These processes, called superradiance and subradiance, are still poorly understood due to the large number of interacting quantum particles.

cQED with driven inhomogeneous emitters. (CREDIT: Nature)

“We were able to monitor and control quantum mechanical light-matter interactions at nanoscale,” says co-corresponding author Joonhee Choi, a former postdoctoral scholar at Caltech who is now an assistant professor at Stanford University.


While the research is primarily fundamental and expands our understanding of the mysterious world of quantum effects, this discovery has the potential to one day help pave the way to more efficient quantum memories in which information is stored in an ensemble of strongly coupled atoms. Faraon has also worked on creating quantum storage by manipulating the interactions of multiple vanadium atoms.

Collectively induced transparency (CIT) in the cavity reflection spectrum, resulting from quantum interference and collective response induced by the interplay between driven inhomogeneous emitters and cavity photons. (CREDIT: Nature)

“Besides memories, these experimental systems provide important insight about developing future connections between quantum computers,” says Manuel Endres, professor of physics and Rosenberg Scholar, who is a co-author of the study.

The research team’s findings were published in the journal Nature.


The CIT phenomenon represents a significant breakthrough in the field of quantum mechanics, which studies the behavior of matter and energy at the smallest scales. The discovery could have far-reaching implications, from advancing our understanding of the fundamental nature of the universe to improving the efficiency of technology.

At its core, the CIT phenomenon is the result of a delicate balance between the collective behavior of groups of atoms and the interactions between those atoms and light. This balance can be disrupted by adjusting the frequency of the laser, creating a transparency window in which the light passes through the cavity unimpeded.

The discovery has been met with excitement from researchers in the field, who see it as a significant step forward in our understanding of quantum mechanics.

“The discovery of CIT is just the beginning of our research into the behavior of matter at the quantum level,” says Faraon. “We look forward to exploring this exciting new frontier and discovering even more about the mysterious world of quantum mechanics.”

The researchers plan to continue studying CIT and its potential applications in quantum technology. They hope to develop new methods for manipulating quantum particles and creating more efficient quantum memories.


Overall, this discovery of CIT could be a game-changer for the field of quantum mechanics and the development of quantum technology. As researchers continue to explore the potential applications of CIT, we can expect to see significant advances in the field of quantum computing and the development of new technologies that take advantage of the unique properties of quantum particles.

For more science and technology news stories check out our New Discoveries section at The Brighter Side of News.


Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.


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