Home > Press > Perfect transmission through barrier using sound: New study experimentally proved for the first time a century-old quantum theory that relativistic particles can pass through a barrier with 100% transmission
The phononic crystals are made by artificially placing the acrylic posts in the special pattern. CREDIT The University of Hong Kong |
Abstract:
The perfect transmission of sound through a barrier is difficult to achieve, if not impossible based on our existing knowledge. This is also true with other energy forms such as light and heat.
A research team led by Professor Xiang Zhang, President of the University of Hong Kong (HKU) when he was a professor at the University of California, Berkeley, (UC Berkeley) has for the first time experimentally proved a century old quantum theory that relativistic particles can pass through a barrier with 100% transmission. The research findings have been published in the top academic journal Science.
Just as it would be difficult for us to jump over a thick high wall without enough energy accumulated. In contrast, it is predicted that a microscopic particle in the quantum world can pass through a barrier well beyond its energy regardless of the height or width of the barrier, as if it is "transparent".
As early as 1929, theoretical physicist Oscar Klein proposed that a relativistic particle can penetrate a potential barrier with 100% transmission upon normal incidence on the barrier. Scientists called this exotic and counterintuitive phenomenon the "Klein tunneling" theory. In the following 100 odd years, scientists tried various approaches to experimentally test Klein tunneling, but the attempts were unsuccessful and direct experimental evidence is still lacking.
Professor Zhang's team conducted the experiment in artificially designed phononic crystals with triangular lattice. The lattice's linear dispersion properties make it possible to mimic the relativistic Dirac quasiparticle by sound excitation, which led to the successful experimental observation of Klein tunneling.
"This is an exciting discovery. Quantum physicists have always tried to observe Klein tunneling in elementary particle experiments, but it is a very difficult task. We designed a phononic crystal similar to graphene that can excite the relativistic quasiparticles, but unlike natural material of graphene, the geometry of the man-made phononic crystal can be adjusted freely to precisely achieve the ideal conditions that made it possible to the first direct observation of Klein tunneling," said Professor Zhang.
The achievement not only represents a breakthrough in fundamental physics, but also presents a new platform for exploring emerging macroscale systems to be used in applications such as on-chip logic devices for sound manipulation, acoustic signal processing, and sound energy harvesting.
"In current acoustic communications, the transmission loss of acoustic energy on the interface is unavoidable. If the transmittance on the interface can be increased to nearly 100%, the efficiency of acoustic communications can be greatly improved, thus opening up cutting-edge applications. This is especially important when the surface or the interface play a role in hindering the accuracy acoustic detection such as underwater exploration. The experimental measurement is also conducive to the future development of studying quasiparticles with topological property in phononic crystals which might be difficult to perform in other systems," said Dr. Xue Jiang, a former member of Zhang's team and currently an Associate Researcher at the Department of Electronic Engineering at Fudan University.
Dr. Jiang pointed out that the research findings might also benefit the biomedical devices. It may help to improve the accuracy of ultrasound penetration through obstacles and reach designated targets such as tissues or organs, which could improve the ultrasound precision for better diagnosis and treatment.
On the basis of the current experiments, researchers can control the mass and dispersion of the quasiparticle by exciting the phononic crystals with different frequencies, thus achieving flexible experimental configuration and on/off control of Klein tunneling. This approach can be extended to other artificial structure for the study of optics and thermotics. It allows the unprecedent control of quasiparticle or wavefront, and contributes to the exploration on other complex quantum physical phenomena.
####
For more information, please click here
Contacts:
Melanie Wan
852-285-92600
Copyright © University of Hong Kong
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
The article published in Science:
Related News Press |
Quantum Physics
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
News and information
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Possible Futures
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Optical computing/Photonic computing
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024
Discoveries
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
Announcements
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Photonics/Optics/Lasers
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||