Two-Photon Airy Disk
  We report an experimental observation of quantum Airy disk diffraction pattern using an entangled two-photon source. In contrast to the previous quantum lithography experiments where the subwavelength diffraction patterns were observed in the far field limit, we perform the Fraunhofer diffraction experiment with a convex lens. The experimental result shows that the two-photon Airy disk is provided with the super-resolution spot, which surpasses the classical diffraction limit. In particular, the spot size can be well controlled by the focal length, which adapted to optical super-focusing. Our experiment can promote potential application of quantum lithography. 
Hai-Bo Wang, Xin-Bing Song, De-Qin Xu, Jun Xiong, Xiangdong Zhang, and   Kaige Wang
quant-ph physics.optics