<P> He was an active professor at Illinois from 1951 to 1975 and then became Professor Emeritus . In his later life, Bardeen remained active in academic research, during which time he focused on understanding the flow of electrons in charge density waves (CDWs) through metallic linear chain compounds . His proposals that CDW electron transport is a collective quantum phenomenon (see Macroscopic quantum phenomena) were initially greeted with skepticism . However, experiments reported in 2012 show oscillations in CDW current versus magnetic flux through tantalum trisulfide rings, similar to the behavior of superconducting quantum interference devices (see SQUID and Aharonov--Bohm effect), lending credence to the idea that collective CDW electron transport is fundamentally quantum in nature . (See quantum mechanics .) Bardeen continued his research throughout the 1980s, and published articles in Physical Review Letters and Physics Today less than a year before he died . </P> <P> In 1956, John Bardeen shared the Nobel Prize in Physics with William Shockley of Semiconductor Laboratory of Beckman Instruments and Walter Brattain of Bell Telephone Laboratories "for their researches on semiconductors and their discovery of the transistor effect". </P> <P> At the Nobel Prize ceremony in Stockholm, Brattain and Shockley received their awards that night from King Gustaf VI Adolf . Bardeen brought only one of his three children to the Nobel Prize ceremony . King Gustav chided Bardeen because of this, and Bardeen assured the King that the next time he would bring all his children to the ceremony . He kept his promise . </P> <P> In 1957, Bardeen, in collaboration with Leon Cooper and his doctoral student John Robert Schrieffer, proposed the standard theory of superconductivity known as the BCS theory (named for their initials). </P>

Physisist who won a 2009 presidential medal of freedom