Engineering Physics

9.7 Josephson’s effect

In 1962, Josephson passed electrical current consisting of correlated pairs of electrons across an insulating gap (~ 10 Å) between two superconductors. This effect is known as Josephson effect.

Josephson effect can be explained in the following way. As shown in Fig. 9.16(a), a rectangular superconducting bar is connected in series with a battery (B), plug key (K) and an ammeter (A). A voltmeter (V) is connected across the superconductor. Since the superconductor has zero resistance, so the voltmeter shows zero reading. Whereas the ammeter shows the current through the superconductor. Next, the superconductor is cut into two pieces as shown in Fig. 9.16(b). If the gap between the two pieces is about 1 cm, then current will ...