US scientists observe quantum heat waves at room temperature in a world first

In a global first, physicists at the University of California, Los Angeles, have observed a quantum behavior of heat waves at room temperature instead of the ultra-low temperatures that are typically required. The discovery opens up new possibilities for heat management in next-generation quantum devices, overcoming bottlenecks faced earlier. Whether the laptop that you use every day or quantum computers that research labs and startups are building for the future, thermal management is a major issue that is faced by all computing devices. Heat generated during data processing is an impediment to the processing power and scalability of the device. For quantum computers to become as ubiquitous as silicon-based computing today, it is also necessary that they are able to operate at room temperature. Scientists are working on various approaches to make this possible, but doing so would also require quantum properties to work at room temperature. The recent work at UCLA is proof that this can happen. What is phonon focusing? Phonon focusing is a type of quantum behavior where phonons carry heat in vibrational energy packets through non-metallic material in a specific pattern, much like light rays emerging from a star. This is different from heat-transporting phonons at room temperature, which spread out evenly in all directions. According to Yongjie Hu, a mechanical and aerospace engineer at UCLA, this opens up a new way of thinking about thermal management, as heat can now be guided and redistributed with nanoscale precision at room temperature. This is also a foundation for quantum thermal engineering. “”Looking ahead, the discovery of ambient phonon wave dynamics, together with the ability to directionally control heat flow and precisely tailor phonon coupling to other energy carriers, could open new frontiers beyond classical thermal-management frameworks,” the researchers wrote in a paper. How did they do it? In their work, the researchers used boron arsenide (BA), a recently discovered semiconductor material that is a good transporter of heat. The crystalline structure of the material creates natural funnels for phonons to travel, thereby giving them the freedom to travel without colliding into each other. The team also used a nanoscale gold probe that served as a heat source and a precise sensor for mapping heat propagation, creating conditions for phonon focusing at a room temperature of 80 Fahrenheit (27 degrees Celsius). The researchers observed distinct patterns that are different from classical heat transfer, thereby proving that wave-governed exotic and quantum transport phenomena do not need only ultra-cold conditions to operate. Interestingly, the researchers also found that the three-dimensional arrangement or atomic orientation of the material could create different ray patterns, giving us more control over how heat moves through the material. Although the phonons were observed moving just 250 nanometers in the experiment, this distance is huge for an experiment of this type and is sufficient evidence for phonon focusing, the researchers concluded. “Comprehensive validation and quantitative analysis of the temperature-dependent experiments further confirm the robustness, reproducibility and nanoscale resolution of the technique,” the researchers added in their paper. The team will now work to convert their lab work into realities of the real world. The research findings were published in the journal Nature Physics. Get the latest in engineering, tech, space & science - delivered daily to your inbox.Ameya is a science writer based in Hyderabad, India. A Molecular Biologist at heart, he traded the micropipette to write about science during the pandemic and does not want to go back. He likes to write about genetics, microbes, technology, and public policy.