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
New Directions - Paul Courant
Paul Courant is the University Librarian and Dean of Libraries at the University of Michigan, overseeing 19 libraries on the Ann Arbor campus. As Provost at UM he was engaged with campus-wide issues such as affirmative action in admissions and budget shortfalls due to reduced state support. As a professor of economics and public policy as well, Paul Courant brings a unique perspective to the issues of economics of universities, libraries and archives; research support; scholarly communication; and partnerships between faculty and libraries.
For further information:
http://www-personal.umich.edu/~pnc/
http://www.lib.umich.edu/