Single flux quantum circuits with damping based on dissipative transmission lines

We propose and demonstrate the functioning of a special rapid single flux quantum (RSFQ) circuit with frequency-dependent damping. This damping is achieved by shunting individual Josephson junctions by pieces of open-ended RC transmission lines. Our circuit includes a toggle flip-flop cell and Josephson transmission lines transferring single flux quantum pulses to and from this cell, as well as DC/SFQ and SFQ/DC converters. Due to the desired frequency dispersion in the RC line shunts which ensures sufficiently low noise at low frequencies, such circuits are well suited for integrating with the flux/phase Josephson qubit and enable its efficient control.