Single flux quantum circuits with damping based on dissipative transmission lines

TL;DR

This paper introduces a novel RSFQ circuit with frequency-dependent damping using dissipative transmission lines, enhancing integration with Josephson qubits by reducing low-frequency noise.

Contribution

It presents a new damping approach for RSFQ circuits using RC transmission lines, improving qubit integration and noise performance.

Findings

Successful demonstration of the circuit operation

Effective frequency-dependent damping achieved

Potential for improved qubit control and integration

Abstract

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, 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.