This is a fundamental result; the conductance does not take on arbitrary values but is quantized in multiples of the conductance quantum formula_10, which is expressed through the electron charge formula_11 and the Planck constant formula_12. The integer number formula_7 is determined by the width of the point contact and roughly equals the width divided by half the electron wavelength. As a function of the width of the point contact (or gate voltage in the case of GaAs/AlGaAs heterostructure devices), the conductance shows a staircase behavior as more and more modes (or channels) contribute to the electron transport. The step-height is given by formula_14.