Experimental and computational results on programmable Josephson junction array (JJA) chips based on superconductor-insulator-superconductor (SIS) junctions are presented. Implications of circuit design and fabrication process on the performance are discussed. We introduce a method to decrease the attenuation of the pump microwave. Different designs are compared, suggesting that 1 V chips opera...

We fabricate superconductor–graphene– superconductor Josephson junctions with superconducting regions made of lead (Pb). The critical current through graphene may be modulated by the external magnetic field; the resulting Fraunhofer interference pattern shows several periods of oscillations, suggesting that the junction is uniform. Deviations from the perfect Fraunhofer pattern are observed, an...

We study the supercurrent in a superconductor/ferromagnet/superconductor graphene junction. In contrast to its metallic counterpart, the oscillating critical current in our setup decays only weakly upon increasing the exchange field and junction width. We find an unusually large residual value of the supercurrent at the oscillatory cusps due to a strong deviation from a sinusoidal current-phase...

We show that a huge thermoelectric effect can be observed by contacting a superconductor whose density of states is spin split by a Zeeman field with a ferromagnet with a nonzero polarization. The resulting thermopower exceeds kB/e by a large factor, and the thermoelectric figure of merit ZT can far exceed unity, leading to heat engine efficiencies close to the Carnot limit. We also show that s...

Andreev reflection in ferromagnet-superconductor junctions is derived in a regime in which Zeeman splitting dominates the response of the superconductor to an applied magnetic field. Spin-up and spin-down Andreev reflections are shown to be resolved as voltage is increased. In the metallic limit, the transition from Andreev to tunnel conductivity in the spin-up channels has a non trivial behavi...

| An integrated multipurpose setup for the automated testing of superconductor devices and circuits has been designed, implemented, and installed in the RSFQ Laboratory of the State University of New York at Stony Brook. The ex-tendible and modular design of the setup allows a wide variety of low-frequency superconductor experiments to be carried out including those that require immediate inter...

– We study the current-phase relation of the superconductor/normal/superconductor (SNS) junction imbedded in a superconducting loop. Considering the current conservation and free energy minimum conditions, we obtain the persistent currents of the SNS loop. At finite temperature we can explain the experimentally observed highly non-sinusoidal currents which have maxima near the zero external flu...

To reveal the influence of the exchange interaction on the Josephson effect, the d.c. Josephson current in unconventional-superconductor / ferromagnet / unconventional-superconductor junctions is studied. When the two superconductors have d-wave symmetry, the Josephson current is drastically suppressed with the increase of the exchange interaction. On the other hand, when the two superconductor...