John Bardeen
Josephson effect controversy

Bardeen became interested in superconducting tunnelling in the summer of 1960 after consulting for the General Electric Research Laboratory in Schenectady, New York where he learned about experiments done by Ivar Giaever at the Rensselaer Polytechnic Institute which suggested that electrons from a normal material could tunnel into a superconducting one.

In June 8, 1962, Brian Josephson, then 23, submitted to Physics Letters his prediction of a super-current flow across a barrier, effect which later became known as the Josephson effect. Bardeen challenged Josephson's theory on a note in his own paper received ten days later by Physical Review Letters:

In a recent note, Josephson uses a somewhat similar formulation to discuss the possibility of superfluid flow across the tunneling region, in which no quasi-particles are created. However, as pointed out by the author (reference 3), pairing does not extend into the barrier, so that there can be no such superfluid flow.

The matter was further discussed on the 8th International Conference on Low Temperature Physics held September 16 to 22, 1962 at Queen Mary University of London. While Josephson was presenting his theory, Bardeen rose to describe his objections. After an intense debate both men were unable to reach a common understanding, and at points Josephson repeatedly asked Bardeen, "Did you calculate it? No? I did."

In 1963, experimental evidence and further theoretical clarifications were discovered supporting the Josephson effect, notably in a paper by Philip W. Anderson and John Rowell from Bell Labs. After this, Bardeen came to accept Josephson's theory and publicly withdrew his previous opposition to it at a conference held in August 1963. Bardeen also invited Josephson as a postdoc in Illinois for the academic year of 1965–1966, and later nominated Josephson and Giaever for the Nobel Prize in Physics, which they received in 1973.
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