Superconducting nanotransistor based digital logic gates

We describe the fabrication and digital logic operation of superconducting nanotransistors. The nanotransistor is a superconducting weak-link device that has integrated hot-phonon injector heaters to control its switching critical current. The fabrication process utilizes a self-aligned method, where the heater acts as a mask for reactive ion etching to define the device pattern. This device is much simpler to fabricate than previously reported controllable superconducting transistors and the principle of operation makes it possible to use a single nanotransistor connected to a load resistor as a NOT logic gate, allowing lower power consumption and improved levels of integration.