Today Kai Wu and I gave a presentation at Jan Zaanen’s group meeting called the “Stripe Club”. Our presentation was named “The motion of a single exciton in a bilayer quantum antiferromagnet” (PDF, 1.9 MB). In summary: we developed a spin wave theory for the bilayer Heisenberg model in order to describe the motion of an exciton through such a bilayer, which we solved using the self-consistent Born approximation. Recently, we obtained numerical results for the exciton spectral function. It appears to be that the Ising-type ladder spectrum reappears even though quantum fluctuations are taken into account, as you can see in the following ‘teaser’ result for alpha=0.2.