Burner shaping glass art at a glass blowing studio

Glass is supposed to stop heat, not usher it through at near-quantum efficiency. But a new experiment shows that when amorphous silicon dioxide is pulled into a junction only one atom wide, its behavior changes dramatically: heat travels through the tiny strand in discrete steps, reaching as much as 40% of the quantum limit. The discovery could help engineers rethink heat management in shrinking electronics.

The result comes from a team led by Longji Cui and Sai C. Yelishala, whose study appeared in Nature Nanotechnology on October 13, 2026. Using a custom scanning thermal probe with picowatt sensitivity, the researchers pressed two pieces of glass together and gradually pulled them apart. The contact narrowed from a nanoscale bridge to an atomic thread before finally breaking.

That setup allowed the team to watch glass transition from its familiar role as a poor, disorder-driven thermal conductor to a ballistic conductor at the atomic limit. The paper’s abstract says the junction carried phononic heat at up to 40% of the quantum limit at room temperature—roughly an order of magnitude above the phonon conductance measured in crystalline gold.

The apparent contradiction comes down to scale. In ordinary glass, the irregular arrangement of atoms scatters the vibrations, or phonons, that transport heat. At one atom across, there is essentially no wider structure for those vibrations to ricochet through. Instead, the team’s measurements indicate that the Debye frequency—the highest frequency at which a material’s vibrational modes can operate—sets the ceiling for heat flow more than bulk disorder does.

That matters because silicon dioxide is already deeply embedded in chip manufacturing, where it serves as an electrical insulator between conducting components. As transistors and other devices become smaller, moving heat away from active regions becomes increasingly difficult. A material that blocks electrical current while efficiently carrying thermal energy could eventually support new approaches to nanoscale interconnects, though this experiment is still fundamental research rather than a ready-made cooling component.

The researchers also see the atomic junction as a platform for studying coherent, wave-like phonon transport. Their work points toward possible thermal devices—including a thermal diode or transistor—that could control heat much like electronic components control electrical current. Turning a one-atom laboratory bridge into something manufacturable will require substantial engineering, but the finding overturns a basic assumption: at the smallest scale, glass’s disorder may no longer be the thing that limits heat.

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Burner shaping glass art at a glass blowing studio via Wikimedia Commons with usage type - Commercial license. By Quino Al quinoal - https://unsplash.com/photos/8ji8tBM824Uarchive copy at the Wayback Machine, CC0, https://commons.wikimedia.org/w/index.php?curid=62296426