Bipolar Quantum Voltage Generator Based on Zero Crossing Shapiro Steps in Asymmetric 2J-SQUIDs

On an asymmetric two-junction superconducting quantum interference device (2J-SQUID) driven by one sinusoidal rf signal, the observation of zero-crossing Shapiro steps have been reported. In this paper, the loop inductance, L and the ratio of critical currents of Josephson junctions of the 2J-SQUID were optimized by a simulation. Using three voltage states those this asymmetric 2J-SQUID has, the bipolar quantum voltage generator that has three asymmetric 2J-SQUIDs and two control lines, was designed based on obtained parameters. Within the bias current -voltage curves with seven different combinations of the control currents, seven quantized voltages were obtained at the zero bias current.