It sounds a bit like science fiction, but researchers in Canada say they have built a quantum device that can generate controlled bursts of sound-like particles at temperatures just above absolute zero.
The team at McGill University, working with the National Research Council of Canada, developed the device using a two-dimensional crystal that confines electrons to a channel only a few atoms wide. The material used in the device was synthesized at Princeton University.
When an electrical current pushes electrons through that ultra-thin pathway at high speeds, the electrons release excess energy as bursts of sound-like vibrations known as phonons.
Researchers said they were able to generate those phonons in predictable, controllable patterns, a step toward devices that manipulate sound at the quantum level and, eventually, phonon lasers.
“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 experiments were carried out at temperatures ranging from about 10 milli-Kelvin to 3.9 Kelvin. At those temperatures, the researchers said electrons behave in a more orderly way, making quantum phenomena easier to observe.
“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 said.
“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.”
The next phase of the research will test the device with other materials, including graphene, which the researchers said could let it operate at 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.
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 Z. T. Wang, M. Hilke, N. Fong, D. G. Austing, S. A. Studenikin, K. W. West and L. N. Pfeiffer.
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