Physics 111 Advanced Laboratory. Professor Sumner Davis This video accompanies the Josephson Junction Experiment, providing students with an introduction to the theory, apparatus, and procedures. Superconducting phenomena are among the most fascinating features in physics, and the Josephson Effect is the most interesting of all. In 1962, Brian Josephson predicted that electron pairs could tunnel without resistance through an insulating barrier between two superconductors. Here we use a point contact between niobium wire with a thin oxide layer and a niobium screw at liquid helium temperatures. Both the DC and AC Josephson effects are observed and measured. A DC current can flow through the junction with no potential difference, but when a DC voltage is applied together with a small alternating voltage, the I-V curve shows a characteristic step structure. From this step structure the value of 2e/h can be calculated easily and accurately, an exciting consequence of the properties of the junction. In this experiment you will learn some low temperature techniques and four wire measurements that are used in many research laboratories. http://advancedlab.org

Chem 1A, 002 - Spring 2013 Creative Commons 3.0: Attribution-NonCommercial-NoDerivs

Philosophy 135, 001 - Spring 2014 Creative Commons 3.0: Attribution-NonCommercial-NoDerivs

Public Health Preparedness and Emergency Response Professor Thomas Aragon