High Temperature Superconductivity  Here at the physics
department of the National University of Singapore, Tony Leggett
is about to speak on “Cuprate superconductivity: the current
state of play”. I’ll take notes and throw them on this blog in a
rough form. As always, my goal is to start some interesting
conversations. So, go ahead and ask questions, or fill in some
more details. Not everything I write here is something I
understand!  Certain copper oxide compounds can be
superconductive at relatively high temperatures — for example,
above the boiling point of liquid nitrogen, 77 kelvin. These
compounds consist of checkerboard layers with four oxygen atoms
at the corners of each square and one copper in the middle. It’s
believed that the electrons move around in these layers in an
essentially two-dimensional way. Two-dimensional physics allows
for all sorts of exotic possibilities! But nobody is sure how
these superconductors work. The topic has been around for about
25 years, but according to Leggett, there