Anomalous superconducting effect in coherently coupled Josephson junctions

T. Claeson, Floriana Lombardi, Thilo Bauch +5 more

D. Z. Haxell, Marco Coraiola, Manuel Hinderling +9 more

High Resolution Image Download MS PowerPoint Slide We perform switching current measurements of planar Josephson junctions (JJs) coupled by a common superconducting electrode with independent control over the two superconducting phase differences. We observe an anomalous phase shift in the current–phase relation of a JJ as a function of gate voltage or phase difference in the second JJ. This demonstrates the nonlocal Josephson effect, and the implementation of a φ 0 -junction which is tunable both electrostatically and magnetically. The anomalous phase shift is larger for shorter distances between the JJs and vanishes for distances much longer than the superconducting coherence length. Results are consistent with the hybridization of Andreev bound states, leading to the formation of an Andreev molecule. Our devices constitute a realization of a tunable superconducting phase source and could enable new coupling schemes for hybrid quantum devices.

D. Rogula, M. Sztyren

Sadashige Matsuo, Takaya Imoto, Tomohiro Yokoyama +6 more

A Josephson junction (JJ) is a key device for developing superconducting circuits, wherein a supercurrent in the JJ is controlled by the phase difference between the two superconducting electrodes. When two JJs sharing one superconducting electrode are coherently coupled and form the Andreev molecules, a supercurrent of one JJ is expected to be nonlocally controlled by the phase difference of another JJ. Here, we evaluate the supercurrent in one of the coupled two JJs as a function of local and nonlocal phase differences. Consequently, the results exhibit that the nonlocal phase control generates a finite supercurrent even when the local phase difference is zero. In addition, an offset of the local phase difference giving the JJ ground state depends on the nonlocal phase difference. These features demonstrate the anomalous Josephson effect realized by the nonlocal phase control. Our results provide a useful concept for engineering superconducting devices such as phase batteries and dissipationless rectifiers.

R. Bonifacio, Daniel N. Rogovin, Marlan O. Scully

C. Guarcello, R. Citro, O. Durante +6 more

This paper investigates the behavior of an rf-superconducting quantum interference device formed by embedding two anomalous Josephson junctions in a superconducting ring with a non-negligible inductance. The authors show that an in-plane magnetic field can be used to induce and control the hysteretical response of the device. In this way, the proposed system can be effectively used to detect and measure the anomalous Josephson effect.