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Theory turned into practice as new work from the Pritzker School of Molecular Engineering at the University of Chicago revealed the surprising ability of diamond defects to concentrate
Theory turned into practice as new work from the Pritzker School of Molecular Engineering at the University of Chicago revealed the surprising ability of diamond defects to concentrate optical energy.
Researchers have developed atomic antennas that provide a million-fold increase in optical energy by using germanium vacancy centers in diamond. This advance enables the study of fundamental physics and opens new avenues of research. Collaboration between theoretical and experimental groups was crucial for this breakthrough.
Just as a radio antenna picks up an airborne broadcast and concentrates the energy into music, individual atoms can collect and concentrate light energy into a strong, localized signal that researchers can use to probe the basic building blocks of matter.
The stronger the intensity gain, the better the antenna. However, scientists have never been able to detect the potentially large density increase of some “atomic antennas” in solid materials because they are solid.
“When atoms are present in solids, they often interact with the environment. “They have a lot of disorder, they get shaken by phonons, and they encounter other distortions that reduce the coherence of the signal,” said Alex High, an associate professor at the Pritzker University School of Molecular Engineering in Chicago.
In a new article published June 7 Nature PhotonicsA multi-enterprise team led by High Lab solved this problem. They used germanium vacancy centers in diamond to create a six-order optical energy gain, a regime difficult to achieve with conventional antenna structures.
This million-fold increase in energy creates what the paper calls an “exemplary” optical antenna and provides a new tool that opens the door to entirely new areas of research.
“This is not just a breakthrough in technology. This is also a breakthrough in fundamental physics,” said PME doctoral candidate Zixi Li, co-author of the paper. “Although it is well known that an excited atomic dipole can generate a near field of enormous intensity, no one has ever demonstrated this in an experiment before.” .”
The main feature of the optical antenna is that it forms an electronic dipole that oscillates upon resonance excitation.
“Optical antennas are basically structures that interact with electromagnetic fields and absorb or emit light at specific resonances as electrons move between energy levels in these color centers,” High said.
As an electron transitions between the excited state and the ground state, it oscillates and concentrates a relatively large amount of energy, making a solid atomic optical dipole, in theory, a perfect antenna.
“This is not just a breakthrough in technology. This is also a breakthrough in fundamental physics.”
— PhD candidate Zixi Li, UChicago Pritzker School of Molecular Engineering
Theoretical ability was preserved by the fact that atoms are in a solid state, subject to all the jostling, electronic interference, and general noise that comes from being part of a cramped structure. Color centers—tiny defects in diamonds and other materials with interesting quantum properties—provided the team with a solution.
“What has been observed over the last seven or eight years is that certain types of color centers may be immune to environmental influences,” High said.
Co-author Darric Chang, from the Institute of Photonic Sciences in Barcelona, Spain, said this opens up interesting research possibilities.
“To me, the most interesting aspect of the color center is not only the improvement of the field, but also the fact that the light emitted is quantum mechanical in nature,” he said. “This makes it interesting to consider whether a ‘quantum optical antenna’ could have different functions and operating mechanisms compared to a classical optical antenna.”
But turning this theory into a practical antenna took years, collaboration with researchers around the world, and theoretical guidance from the University of Chicago Galli Group.
“The collaboration between theory, computation, and experiment pioneered by Alex High has not only improved the understanding and interpretation of fundamental science, but also opened new avenues of research on the computational side,” said PME Liew Family Professor Gilia Galli. writes on paper. “The collaboration has been extremely fruitful.”
Atomic level imaging is a combination of gain and bandwidth (the strength of the signal and the amount of signal that can be examined). Therefore, co-author Xinghan Guo sees the new technique as a complement to existing techniques, not a replacement.
“We offer much higher gains, but our bandwidth is narrower,” said Guo, who recently completed his doctorate at PME and is now a postdoctoral researcher at Yale University. “If you have a very selective signal that has narrow bandwidth but needs a lot of amplification, you can come to us.”
The new technique offers other benefits beyond a stronger signal. Although existing techniques such as single-molecule Raman spectroscopy and FRET spectroscopy amplify the signal by illuminating it with light, these techniques require only nanowatts of energy to activate. This means a strong signal without the bleaching, warming and background fluorescence created by excessive light.
Unlike traditional plasmonic antennas, Germanium cavity centers do not consume energy during their use.
“The magic of the color center is that it is both point-like and retains extreme field enhancement by preventing loss of plasmonic material,” Chang said.
For Hai, the most interesting thing is not the new shape of the antenna, but the potential discoveries they will make.
“The interesting thing is that this is a common feature,” High said. “We can integrate these color centers into multiple systems and then use them as local antennas to develop new processes that create new devices and help us understand how the universe works.”
Source: Port Altele
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