Josephson junctions & SQUIDs

ring2Josephson junctions and  SQUIDs (Superconducting Quantum Interference Devices) are one of the most important instruments found in the majority of research laboratories worldwide. They offer a rich spectrum of beneficial  applications: Testing the fundamentals of quantum mechanics, quantum ionformation and chaotic complexity in classical physics;

Commercial applications in industrial metrology,   geophysical systems and medicine as a noninvasive technique for investigating  the  human body.   Yet,  there remain still new phenomena to be uncovered for this system which in turn carry the potential for new applications.  Of special interest are novel transport phenomena in presence of external ac- and dc-currents. In this context, the phenomenon of  absolute negative conductance (ANC) plays a particularly intriguing role. Here, ANC means that the system's response is opposite  to a small external dc current.

1. J. Spiechowicz, P. Hanggi, J. Łuczka,  Josephson junction ratchet: The impact of finite capacitances, Phys. Rev. B 90, 054520 (2014)

2. J. Spiechowicz and J. Łuczka, Efficiency of a SQUID Ratchet Driven by External Current, New. J. Phys. 17, 023054 (2015)