Branched Electron Current from Quantum Point Contacts and Novel Device Concepts

Simulations have been performed of electron current flow through quantum point contacts demonstrating that novel device concepts ought to be feasible for fabrication. Using a finite difference method, wave packets, characterized at a temperature of approximately 44 K and at different transverse quantum modes, are shown to propagate through a quantum point contact with branched paths. A quantum switching effect is then generated when the number of occupied transverse modes is changed by tuning the width of a quantum point contact. The transmission probabilities and angular probability distribution for electrons ejected from quantum point contacts of typical shapes are calculated, which allows us to investigate how the geometrical parameters affect the branched electron flow. Based on the findings, two types of quantum switch devices were designed, one containing a parabolic reflector. The properties of the two devices are compared, particularly regarding the switching efficiency. Such concepts may not only lead to low-temperature devices but may also help make higher-temperature quantum devices more feasible.