Thermal conductance quantum
In physics, the thermal conductance quantum describes the rate at which heat is transported through a single ballistic phonon channel of temperature. It is given by:
The thermal conductance of any electrically insulating structure that exhibits ballistic phonon transport is a positive integer multiple of The thermal conductance quantum was first measured in 2000. These measurements employed suspended silicon nitride nanostructures that exhibited a constant thermal conductance of 16 at temperatures below approximately 0.6 kelvin.
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 and room temperature.
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 is an integer, also known as TKNN number. Then
where is the thermal conductance quantum defined above.
