BALLISTIC TRANSPORT IN ELECTRON-STUB-TUNER SUPERLATTICES

An electron stub tuner (EST) consists of a quantum wire to which is attached a lateral branch or stub, of finite length that can be controlled by a gate. The quantum interference between electron waves in the stub and the wire makes the transmission, as a function the stub length, vary periodically between zero and one when one mode is present in the wire. We consider superlattices composed of EST units and show hen; with a suitable choice of unit cell the transmission can have a form approaching: a square wave, which is desirable for applications such as analog -to-digital converters. a unit cell composed of a double stub or crossbar geometry is particularly promising in this regard. We also consider the multi-mode case and show how periodic patterns involving several transmission plateaus are possible.