Ballistic transmission in perpendicular quantum point contacts

Abstract
We have measured the series resistance of a pair of quantum point contacts (QPC’s) oriented with their axes mutually perpendicular. In zero magnetic field the series resistance of the QPC’s is the classical Ohmic sum of the two individual resistances. The degree of ballistic transmission increases sharply as the magnetic field is increased and is also weakly dependent on the width of the QPC. This behavior is interpreted in terms of a simple model involving the classical ballistic trajectory of the electrons.