Every electronic and optoelectronic device generates heat, and today that heat is managed almost entirely from the outside. Heatsinks, fans, cold plates and refrigerators are bulky exterior measures bolted onto a chip or package after the fact. They treat heat as a single averaged quantity to be removed in bulk, even though the heat is actually produced locally, component by component, deep inside the circuitry.

Quantum thermal devices offer a fundamentally different approach. Because they are tiny, heat-management circuitry can, in principle, be built right next to each electronic or optoelectronic component that needs it.

Instead of one bulk, averaged solution for an entire chip, each component could have its own tailored thermal circuit beside it, steering heat away exactly where it arises. That is the long-term technological promise motivating this field.

Recent technological advances have enabled the development of increasingly sophisticated, sharper displays for electronic devices. Many modern displays use light-emitting diodes, or LEDs, tiny semiconductor-based components that emit light when an electrical current passes through them.

A proof-of-principle experiment used concentrated sunlight to produce entangled photons

The discovery could improve thermal management in electronics and support advances in quantum and next-generation computing technologies.

Heat usually spreads outward through a solid, making it difficult to control once it begins moving. Until now, a wavelike form of heat transport called phonon focusing had been observed only at extremely low, or cryogenic, temperatures, sharply limiting its study and possible applications.

Researchers at the UCLA Samueli School of Engineering have now shown that phonons, quantum vibrations that carry heat through a material, can travel along concentrated, ray-like paths at room temperature. Rather than dispersing evenly in every direction, the heat followed routes determined by the underlying crystal structure, suggesting a new way to direct thermal energy in future electronics and quantum technologies.