Stable switch action based on quantum interference effect

Although devices working on quantum principles can revolutionize the electronic industry, they have not been achieved yet as it is difficult to control their stability. We show that one can use evanescent modes to build stable quantum switches. The physical principles that make this possible is explained in detail. Demonstrations are given using a multichannel Aharonov - Bohm interferometer. We propose a new $S$ matrix for multichannel junctions to solve the scattering problem.