Exploiting First and Second Shapiro Steps Towards the Reduction of Bias Lines in Programmable Josephson Arrays

Quantum Digital-to-Analog Converters (DACs) based on programmable Josephson array (PJVS) represent the most advanced devices currently employed in ac voltage calibrations. Pulse-driven Josephson technology, compared to PJVS, provides cleaner and faster voltage signals and is the main topic of frontier developments. Although the extension of PJVS frequency range appears to be arduous, some enhancement are still practicable. In this work we demonstrate the possibility of synthesizing stepwise quantum voltage waveforms with half of the bias lines and fewer Josephson junctions by exploiting both first and second Shapiro steps, with no losses in terms of performances.