Coherent absorption of N00N states
  Recent results in deeply subwavelength thickness films demonstrated coherent control and logical gate operations with both classical and single photon light sources. However, quantum processing and devices typically involve more than one photon and non-trivial input quantum states. Here we experimentally investigate two-photon N00N state coherent absorption in a multilayer graphene film. Depending on the N00N state input phase, it is possible to selectively choose between single or two photon absorption of the input state in the graphene film. These results demonstrate that coherent absorption in the quantum regime exhibits unique features opening up applications in multiphoton spectroscopy and imaging. 
Thomas Roger, Sara Restuccia, Ashley Lyons, Daniel Giovannini,   Jacquiline Romero, John Jeffers, Miles Padgett, Daniele Faccio
physics.optics quant-ph