Conductance quantum
The conductance quantum, denoted by the symbol G0, is the quantized unit of electrical conductance. It is defined by the elementary charge e and Planck constant h as: G 0 = 2 e 2 h = 4 α ϵ 0 c {\displaystyle G_{0}={\frac {2e^{2}}{h}}=4\alpha \epsilon _{0}c} = 7.748091729...×10−5 S. It appears when measuring the conductance of a quantum point contact, and, more generally, is a key component of the Landauer formula, which relates the electrical conductance of a quantum conductor to its quantum properties.