Atoms and photons interact in free space in one of nature’s most fundamental processes. The dipolar interaction strength between the two systems is determined by fundamental constants, with one of its limiting factors being the mode volume of the propagating photons.
Superconductivity induced by proximity effect is particularly interesting in graphene.
Strong light-matter interactions in microcavities have been long known to provide means to alter optical and nonlinear properties of the coupled system. As a result of this interaction, one typically observes the emergence of new polaritonic eigenstates of the coupled system.
Recently, the introduction of new impurity states in the superconducting gap has received a lot of attention. Indeed, the search of a new superconducting state dubbed topological superconductivity is strongly based in the combination of doping classical (s-wave) superconductors with magnetic impurities that arrange in a chiral fashion.
The narrow-band semiconductor PbTe superconducts with a Tc an order of magnitude greater than comparable low-density metals, but only when it is doped with valence-skipping elements.