Superconductivity was discovered by Kamerlingh-Onnes one hundred years ago, in 1911, but it was not until 1957 that a truly microscopic theory of this phenomenon was developed by Bardeen,Cooper, and Schrieffer (BCS). The current understanding of superconductivity in solids, as well as superfluidity in 3He, rests on the following main ideas of the BCS theory 11,21: (i) The effective force between quasiparticles in a fermionic many-body system can be attractive, leading to the formation of bound states of two quasiparticles, known as the Cooper pairs; (ii) The Cooper pairs "condense" into the ground state characterized by a macroscopically coherent wave function, in which the gauge symmetry of the normal state is broken.
展开▼
