Abstract: A quantum semiconductor device has a semiconductor substrate, a plurality of quantum boxes formed adjacent to one another in the semiconductor substrate, and a quantum level control unit for changing the effective size of at least one of the quantum boxes, to thereby change the quantum level of each of the quantum boxes. Consequently, according to the present invention, an influence of charges due to peripheral impurities is small, and thereby a compact quantum semiconductor device can be provided. Further, according to the present invention, a highly integrated high-speed switching circuit can be provided.

Abstract: A quantum semiconductor device comprises a channel region formed with a two-dimensional carrier gas, a Schottky electrode structure provided on the channel region for creating a depletion region in the channel region to extend in a lateral direction such that the two-dimensional carrier gas is divided into a first region and a second region, a quantum point contact formed in the depletion region to connect the first and second regions of the two-dimensional carrier gas in a longitudinal direction, an emitter electrode provided on the channel region in correspondence to the first region of the two-dimensional carrier gas, one or more collector electrodes provided on the channel region in correspondence to the second region of the two-dimensional carrier gas, and another Schottky electrode structure provided in correspondence to the first region for creating a depletion region therein such that a path of the carriers entering into the quantum point contact is controlled asymmetrical with respect to a hypothetic