Observation of dc voltage on segments of an inhomogeneous superconducting loop

Abstract

In order to verify a possibility of a dc voltage predicted on segments of an inhomogeneous superconducting loop the Little-Parks oscillations are investigated on symmetrical and asymmetric Al loops. The amplitude of the voltage oscillations $\Delta V$ measured on segments of symmetrical loop increases with the measuring current $I_{m}$ and $\Delta V = 0$ at $I_{m}= 0$ in accordance with the classical Little-Parks experiment. Whereas the $\Delta V$ measured on segments of asymmetric loop has a maximum value at $I_{m}= 0$. The observation of the dc voltage at $I_{m}= 0$ means that one of the loop segments is a dc power source and others is a load. The dc power can be induced by both thermal fluctuation and a external electric noise.