The nature of the superconducting state of the high-T c superconductors

At the present time it is possible to get a reasonably good understanding of the nature of the superconducting state in the recently discovered, high transition temperature cuprate superconductors based on experimental results published over the past year or two. These experiments now impose significant constraints on possible theoretical models which can be used to explain the superconductivity. We show how these experiments impose these constraints and discuss those questions which remain unanswered.Invited talk at the International Conference on Macroscopic Quantum Phenomen a, Smolenice Castle, Czechoslovakia, September 18–22, 1989.I am indebted to J. P. Collman, C. Caley, M. Holcomb, and G. Yee for valuable discussion, comments and criticism. I acknowledge financial support for this work from the Department of Energy (grant number DEFG03-86ER45245). I wish also to thank the Czechoslovak Academy of Sciences for the opportunity to attend the International Conference on Macroscopic Quantum Phenomena at Smolenice, Czechoslovakia, September 1989 and support for my stay.