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Excited photoemitters can cooperate and simultaneously emit a phenomenon called superfluorescence. Researchers from Empa and ETH Zurich, as well as colleagues from IBM Research Zurich, have recently been able to create this effect with ordered long-range nanocrystal supergrids. This discovery could allow future developments in the fields of LED lighting, quantum detection, quantum communication and future quantum computing. The study has just been published in the famous journal Nature.
Some materials spontaneously emit light if they are excited by an external source, for example a laser. This phenomenon is known as fluorescence. However, in many gases and quantum systems, a much stronger light emission can occur when the transmitters of a set spontaneously synchronize their quantum mechanical phase with each other and act together when they are excited. In this way, the resulting luminous flux can be much more intense than the sum of the individual emitters, leading to an ultra-fast and brilliant emission of superfluorescence. However, this only happens when these transmitters meet strict requirements, such as the same emission energy, a high coupling force with the light field and a long coherence time. As such, they interact strongly with one another but are not easily disturbed by their environment. Until now, this has not been possible with technologically relevant materials. Colloidal quantum dots could simply be the ticket; They are a proven and commercially attractive solution, already used in the most advanced LCD TV screens – and meet all requirements.
Researchers from Empa and ETH Zurich, led by Maksym Kovalenko, as well as colleagues from IBM Research Zurich, have now shown that the most recent generation of quantum dots in lead perovskite offers an elegant and practical way to super-fluorescence on demand. For this, the researchers organized perovskite quantum dots in a three-dimensional super-lattice, which allows coherent collective emission of photons, thus creating superfluorescence. This forms the basis for entangled multiphoton state sources, a missing key resource for quantum sensing, quantum imaging and photonic quantum computing.
Birds of a feather fly together
A coherent coupling between quantum dots, however, requires that they all have the same size, shape and composition, because the "feather birds come together" in the quantum universe as well. "Such long-range ordered supergrids can only be obtained from a very monodisperse solution of quantum dots, the synthesis of which has been carefully optimized in recent years," said Maryna Bodnarchuk. , senior scientist at Empa. With such "uniform" quantum dots of different sizes, the research team could then form supergrids by properly controlling the evaporation of the solvent.
The latest evidence of superfluorescence comes from optical experiments conducted at temperatures of about minus 267 degrees Celsius. The researchers discovered that the photons were emitted simultaneously in a brilliant burst: "It was our moment" Eureka! "As soon as we understood that it was a new source of quantum light," said Gabriele Rainó of ETH Zurich and Empa. team that performed the optical experiments.
Researchers view these experiments as a starting point for further exploiting collective quantum phenomena with this unique class of materials. "The overall properties can be improved relative to the sum of its components, so it's possible to go beyond individual quantum dot engineering," added Michael Becker of the ETH Zurich and IBM Research. Controlled generation of superfluorescence and corresponding quantum light could open new possibilities in LED lighting, quantum sensing, quantum cipher communication and future quantum computing.
Source of the story:
Material provided by Swiss Federal Laboratories for Materials Science and Technology (EMPA). Original written by Cornelia Zogg. Note: Content can be changed for style and length.
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