describes the rate at which heat is transported through a single ballistic phonon channel with temperature
It is given by The thermal conductance of any electrically insulating structure that exhibits ballistic phonon transport is a positive integer multiple of
[1] These measurements employed suspended silicon nitride (Si3N4) nanostructures that exhibited a constant thermal conductance of 16
For ballistic electrical conductors, the electron contribution to the thermal conductance is also quantized as a result of the electrical conductance quantum and the Wiedemann–Franz law, which has been quantitatively measured at both cryogenic (~20 mK) [2] and room temperature (~300K).
[3][4] The thermal conductance quantum, also called quantized thermal conductance, may be understood from the Wiedemann-Franz law, which shows that where
is a universal constant called the Lorenz factor, In the regime with quantized electric conductance, one may have where