Non-classical light from superconducting resonators coupled to voltage-biased Josephson junctions

Two coupled Josephson junctions: dc voltage controlled by biharmonic current.

We study transport properties of two Josephson junctions coupled by an external shunt resistance. One of the junctions (say, the first) is driven by an unbiased ac current consisting of two harmonics. The device can rectify the ac current yielding a dc voltage across the first junction. For some values of coupling strength, controlled by an external shunt resistance, a dc voltage across the sec...

Thermal Activation of Superconducting Josephson Junctions

Superconducting quantum circuits (SQCs) are being explored as model systems for scalable quantum computing architectures. Josephson junctions are extensively used in superconducting quantum interference devices (SQUIDs) and in persistent-current qubit systems. Noise excitations, however, have a critical influence on their dynamics. Thus, the primary focus of this research was to investigate the...

Resonant transport through midgap states in voltage-biased Josephson junctions of d-wave superconductors

We study theoretically the ac Josephson effect in voltage biased planar junctions of d-wave superconductors. For some orientations of the superconductors a current peak is found at finite voltage in the current-voltage characteristics. We pick out the relevant physical processes and write down an analytical formula for the current which clearly shows how the midgap state acts as a resonance and...

Fluxon bunching in supercurrent-coupled Josephson junctions.

Anomalous transport in biased ac-driven Josephson junctions: Negative conductances

We investigate classical anomalous electrical transport in a driven, resistively, and capacitively shunted Josephson junction device. Intriguing transport phenomena are identified in chaotic regimes when the junction is subjected to both a time-periodic ac and a constant biasing dc current. The dependence of the voltage across the junction on the dc exhibits a rich diversity of anomalous transp...