Why is the conductance quantized?

1. Mar 8, 2014

wdlang

according to the Landauer formula, the conductance is proportional to the transmission probability.

But the transmission probability is not quantized generally

So why is the conductance quantized?

2. Mar 8, 2014

3. Mar 8, 2014

wdlang

i now see.

So it is not as specular as magnetic quantization in superconductors