Quantum lithography: Toward entangled-photon optics

The advantages of using nonclassical states of light for optical imaging are discussed, with special emphasis on the new field of quantum optical lithography. The classical resolution limit given by the Rayleigh criterion is approximately half of the optical wavelength. However, it has been argued that, by using special quantum states of light and a multiphoton-sensitive material or detector, this limit can be broken. Here, a brief and rigorous overview of this problem is provided, some particularly widespread misconceptions are addressed, and turning quantum lithography into a practical technology is discussed.