Researchers at McGill University have developed a new quantum device that produces tiny sound-like particles called phonons at temperatures just above absolute zero. This advance could help pave the way for phonon lasers, a technology that could potentially be used for communications, medical diagnostics, and advanced sensing.
“Modern communication is primarily based on light, which includes electromagnetic waves and electrical currents. In media like the ocean, sound can travel, but light and electrical currents cannot,” said Michael Hilke, associate professor of physics and study co-author. “In the human body, sound waves can also be a useful tool.”
The device was designed and tested by researchers at McGill University and the National Research Council of Canada, and the materials used in the device were synthesized at Princeton University.
How electrons produce quantum sound
The researchers created the device using a two-dimensional crystal that confines electrons in channels a few atoms wide. When an electric current pushes electrons along this tiny path at high speed, they release excess energy in bursts of sound-like vibrations known as phonons.
Researchers have discovered that these phonons can be generated in predictable and controllable patterns. This is an important step toward practical devices that rely on precisely manipulating sound at the quantum level.
Cooling reveals anomalous quantum behavior
Experiments were performed at temperatures ranging from approximately 10 millikelvin to 3.9 kelvin. At these extremely low temperatures, electrons behave more orderly, making it easier to observe quantum phenomena in which matter behaves like waves rather than ordinary particles.
“At absolute zero, or in the world of quantum physics, there is no sound unless electrons collectively move at or above the speed of sound,” Hilke explained. “Previous work had observed related effects as the electron velocity approached the sound barrier. Our work goes further and shows that existing theory needs to be reevaluated by pushing the system far beyond that point and taking into account that electrons can be very hot even when the host crystal is at a temperature close to absolute zero.”
Aiming for faster communication and medical technology
The next stage of research will look into building devices from other materials such as graphene, which could allow them to operate at even higher speeds.
Future versions of the technology could contribute to faster communication systems, more sensitive detection tools, improved methods for studying biological materials, and advanced medical techniques, Hilke said.
“Phonons are difficult to generate and utilize in a controlled way, so we are exploring new regimes. At a broad level, this is how electrical current and energy are transferred and transformed in advanced electronic materials,” he said.
Research details
The survey results are physical review letter In a paper titled “Resonant magnetophonon emission by supersonic electrons in ultrahigh mobility two-dimensional systems” Written by Michael Hilke et al.
This research was funded by the Natural Sciences and Engineering Research Council of Canada and the Quebec Natural Sciences Foundation.
