# Physicists measure heat flow through a single-atom glass junction: up to 40% of the quantum limit

- Published: 2026-11-15 06:10 UTC
- Section: Science › Physics
- Tags: phononic break junction, amorphous silicon dioxide, thermal conductance quantum, single-atom contact, ballistic phonon transport, Debye frequency, scanning thermal microscopy, heat dissipation in nanoelectronics, thermal diode, thermal transistor
- URL: https://realtech.media/news/rt-efbbf40421cd6b5222524ab3_physicists_measure_heat/

**In room-temperature experiments, a one-atom amorphous silica junction conducted heat at up to 40% of the quantum limit, about ten times more than crystalline gold.**

![Physicists measure heat flow through a single-atom glass junction: up to 40% of the quantum limit](https://realtech.media/media/2026/11/c12c0a37558660cb.png)
*nature.com*

Physicists built a custom scanning thermal probe with picowatt resolution and used it to measure heat transport through glass junctions thinned to a single atom, according to a paper on nature.com [1]. The probe uses thermal feedback to form phononic break junctions. These are the thermal counterpart of the electronic break junctions that have been used for decades to study electron transport at the atomic scale [1]. According to a summary by science-et-vie.com, the team comes from the University of Colorado Boulder and two institutes in Madrid, led by Longji Cui, and the work was reported in mid-October 2026.

## Heat transport in atomic glass junctions

The junctions were made of amorphous silicon dioxide (a-SiO2), an archetypal glass. As the tip was withdrawn from a nano-contact to an atomic contact, the authors recorded in real time a transition from a bulk diffusive heat insulator to a ballistic, efficient heat conductor [1]. At room temperature, atomically thin glass junctions supported phononic thermal conductance of up to 40% of the quantum limit [1]. This is approximately an order of magnitude higher than the phonon thermal conductance of crystalline gold [1].

According to the science-et-vie.com account, two pieces of silica were pressed together and pulled apart slowly. The glass bridge thinned to one atom in width just before breaking. The wire is short-lived, and the study as described does not say how to stabilize it or integrate it into a circuit.

## Role of disorder and the Debye frequency

The authors combined the measurements with atomic simulations. They conclude that intrinsic structural disorder, which strongly affects macroscopic thermal properties, does not fundamentally constrain heat flow at the atomic limit [1]. Instead, they find that the Debye frequency dictates the phononic thermal conductance [1].

The authors expect the approach to serve as an experimental platform for studying heat flow carried by wave-like coherent phonons. They also expect it to enable the engineering of phononic thermal devices such as a thermal diode and a thermal transistor [1]. The paper notes that heat dissipation limits the performance of nanoscale electronic and quantum devices, while the fundamental limits of phonon-mediated heat transport at the atomic scale had remained unknown [1]. The data are available via Figshare, and the code and potentials used in the theoretical analysis are open source. The experiment measures a fundamental property of matter in the laboratory; it is not a ready-made component.

## Sources

1. [nature.com](https://www.nature.com/articles/s41565-026-02308-9)
2. [science-et-vie.com](https://www.science-et-vie.com/technos-et-futur/des-physiciens-ont-etire-du-verre-jusqua-une-epaisseur-dun-seul-atome-son-comportement-thermique-pourrait-aider-a-miniaturiser-les-appareils-electroniques-266372.html)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-efbbf40421cd6b5222524ab3_physicists_measure_heat/