Quantum interference devices and methods for processing interference current

A method for processing an interference current comprising the steps of:

• branching an electron wave propagating through a plurality of quantum-structure paths into plural electron waves confined in the plurality of quantum-structure paths;
• combining the electron waves to generate plural kinds of electron waves having different energy levels and varying in magnitude depending on a phase difference between the branched electron waves;
• detecting currents of the plural kinds of electron waves, respectively;
• and
• forming a non-fluctuating current from the detected currents, the non-fluctuating current not being influenced by fluctuations of the current corresponding to the combined electron waves.

An optical communication system comprising:

• a plurality of terminals each of which has a light signal transmitter and a light signal receiver;
• and
• an optical fiber connected to said plurality of terminals for transmitting a light signal,
• wherein the light signal receiver in each of said terminals includes a photodetector for detecting the light signal sent from the other terminals, said photodetector comprising:
• a plurality of quantum-structure paths for propagating an electron wave therethrough;
• means for branching the electron wave into plural electron waves confined in said plurality of quantum-structure paths;
• means for combining the electron waves to generate plural kinds of electron waves having different energy levels and varying in magnitude depending on a phase difference between the branched electron waves;
• means for detecting currents corresponding to said plural kinds of electron waves, respectively;
• operation means for forming a non-fluctuating current from the detected currents, the non-fluctuating current not being influenced by fluctuations of the current corresponding to combined electron waves;
• and
• means for varying a phase difference between the electron waves from said branching means by directing the light signal to said branching means.

A method for producing a quantum interference device, said method comprising the steps of:

• forming a plurality of quantum structure paths for propagating an electron wave therethrough;
• forming a branching structure for branching the electron wave into plural electron waves confined in said plurality of quantum structure paths;
• forming a combining structure for combining the electron waves to generate plural kinds of electron waves having different energy levels and varying in magnitude depending on a phase difference between the branched electron waves, respectively;
• forming a detector for detecting currents of said plural kinds of electron waves;
• and
• forming an operation circuit for forming a non-fluctuating current from the detected currents, the non-fluctuating current not being influenced by fluctuations of the current corresponding to the combined electron waves.