UCLA scientists discover how to guide heat like light at room temperature | ScienceDaily

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UCLA scientists discover how to guide heat like light at room temperature

Scientists have found a way to make heat travel along precise, ray-like pathways at room temperature, potentially opening a new era of smarter electronic cooling.

Date:<br>August 7, 2026<br>Source:<br>University of California - Los Angeles<br>Summary:<br>Scientists have demonstrated that heat can move through a crystal in focused, wave-like rays at room temperature instead of spreading randomly. The breakthrough could make it possible to route heat around sensitive parts of next-generation chips and quantum devices.<br>Share:

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FULL STORY

UCLA researchers have discovered that heat can be guided along precise, ray-like paths through boron arsenide at room temperature. Credit: AI/ScienceDaily.com

Managing heat efficiently inside solid materials is essential for developing faster, more reliable electronics. Until now, a wave-based form of heat transport called phonon focusing had only been observed at extremely low cryogenic temperatures, which made it difficult to study and limited its potential applications.

Researchers at the UCLA Samueli School of Engineering have now shown that phonons, the atomic vibrations that carry heat and display quantum behavior, can move through a material in concentrated, ray-shaped paths at room temperature. Rather than dispersing evenly in every direction, heat can follow routes determined by the structure of a crystal. The finding could lead to new ways of controlling heat in advanced electronics and quantum technologies.

Guiding Heat Through Boron Arsenide

The study, published in Nature Physics, was led by Yongjie Hu, a professor of mechanical and aerospace engineering at UCLA Samueli. His team observed room-temperature phonon focusing in boron arsenide, a crystalline semiconductor known for its high thermal conductivity.

Materials such as boron arsenide may allow engineers to direct heat along planned routes with nanoscale accuracy instead of waiting for it to spread and then trying to remove it. The process is similar in principle to the way optical fibers channel light along a controlled path.

To observe this behavior, the researchers created a technique for mapping temperature at the nanoscale. In conventional materials, heat spread outward in circular patterns, which is consistent with normal diffusive heat conduction. Boron arsenide produced a very different result. The temperature maps revealed distinct ray-shaped patterns aligned with specific directions in the crystal.

Crystal Structure Shapes Heat Flow

The researchers also found that the pattern of heat flow changed in predictable ways when the orientation of the crystal changed. Different planes of boron arsenide produced sixfold, eightfold, and fourfold focusing patterns.

This quantum phonon behavior remained detectable across distances of one micrometer and may extend for tens of micrometers. That range is large enough to be useful in many modern electronic, photonic and quantum devices.

"This is a fundamental observation that enables us to think about thermal management in a new way," said Hu, the study's corresponding author and a member of the California NanoSystems Institute at UCLA. "By enabling heat to be guided, focused and redistributed with nanoscale precision at room temperature, the discovery establishes a foundation for quantum thermal engineering."

Potential Benefits for AI and Quantum Devices

The ability to control heat at the atomic level could help address major limits in AI hardware, microelectronic devices, aerospace systems and other electronics. Overheating can reduce performance, reliability and scalability in all of these technologies.

Hu said the discovery may also make it possible to adjust how phonons interact with electrons and other energy carriers. That capability could support future advances in quantum information systems and sensing technologies.

Earlier observations of phonon focusing were mostly restricted to temperatures only a few degrees above absolute zero. Under those conditions, phonons can travel long distances without scattering very much. At room temperature, phonons generally scatter more frequently and quickly lose the coherence needed for wave-based transport, causing heat to spread through ordinary diffusion.

Why Boron Arsenide Is Different

The new findings build on Hu's earlier work involving the experimental discovery of boron arsenide in 2018. Since then, his group has developed high-performance thermal interfaces and gallium nitride devices that incorporate boron arsenide for cooling. Those results have underscored the material's potential for next-generation semiconductor systems.

Boron arsenide experiences unusually weak phonon scattering, which allows wave-based heat transport to continue even at room...