Superconducting interface circuit

摘要

Hitachi, Ltd. succeeded in fabricating a superconducting interface circuit in the integrated research activities for Extreme Information processing Functions with a Single Flux Quantum as a Carrier sponsored by the Science and Technology Agency and taking out signals from a superconducting flux quantum circuit that operates a super high speed of 40 to 50GHz at room temperature. The Single Flux Quantum (SFQ, Φ{sub}0=h/2e (h=blank constant, e=elementary charge) circuit that uses the superconducting phenomenon as a information carrier is expected as a circuit that operates at tens of GHz to 100GHz. However, the SFQ circuit is still at the small level of integration and the key of this circuit put to practical use is the connection to a semiconductor circuit. On the other hand, it was difficult take out the signals from the SFQ circuit for use under the room temperature condition even if it operated at super high speed because it is in the cryogenic environment and its output signal level is very small, that is, 0.1 mV. Therefore the superconducting interface circuit was indispensable that amplifies superconducting signals.