Scientists create quantum sound device that could transform communications

"Modern communication is largely based on light, including electromagnetic waves and electrical currents. In a medium such as oceans, sound can travel, whereas 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, while the material used in the device was synthesized at Princeton University.

How Fast Electrons Produce Quantum Sound

The team created the device using a two-dimensional crystal that confines electrons to a channel only a few atoms wide. When an electrical current pushes the electrons through this ultra-thin pathway at high speeds, the electrons release their excess energy as bursts of sound-like vibrations known as phonons.

The researchers found that these phonons can be generated in predictable, controllable patterns, an important step toward practical devices that rely on precisely manipulating sound at the quantum level.

Cooling Unlocks Unusual Quantum Behavior

The experiments were carried out at temperatures ranging from about 10 milli-Kelvin to 3.9 Kelvin. At these extremely low temperatures, electrons behave in a much more orderly way, making it easier to observe quantum phenomena, where matter acts like waves rather than ordinary particles.

"At absolute zero temperatures - that is, the world of quantum physics - no sound is created unless electrons travel collectively at the speed of sound or above," Hilke explained. "Earlier work had observed related effects as electron speeds approached the sound barrier. Our study goes further by pushing the system well beyond that point and showing that existing theories need to be reassessed by considering that electrons can be very hot even if the host crystal is close to absolute zero temperature."

Toward Faster Communications and Medical Technologies

The next phase of the research will investigate building the device from other materials, including graphene, which could allow it to operate at even higher speeds.

According to Hilke, future versions of the technology could contribute to faster communication systems, more sensitive detection tools, improved methods for studying biological materials, and advanced medical technologies.

"Phonons are hard to generate and harness in a controlled way, so we are exploring new regimes. At a broad level, this is about how electrical current and energy moves and is converted inside advanced electronic materials," he said.

Study Details

The findings were published in Physical Review Letters in a paper titled "Resonant magnetophonon emission by supersonic electrons in ultrahigh-mobility two-dimensional systems," by Michael Hilke et al.

The research was funded by the Natural Sciences and Engineering Research Council of Canada and the Fonds de recherche du Québec -- Nature et technologie.