Sub-Rayleigh lithography using high flux loss-resistant entangled states   of light
  Quantum lithography achieves phase super-resolution using fragile, experimentally challenging entangled states of light. We propose a scalable scheme for creating features narrower than classically achievable, with reduced use of quantum resources and consequently enhanced resistance to loss. The scheme is an implementation of interferometric lithography using a mixture of an SPDC entangled state with intense classical coherent light. We measure coincidences of up to four photons mimicking multiphoton absorption. The results show a narrowing of the interference fringes of up to 30% with respect to the best analogous classical scheme using only 10% of the non-classical light required for creating NOON states. 
Shamir Rosen, Itai Afek, Yonatan Israel, Oron Ambar and Yaron   Silberberg
quant-ph