Quantum Interferometric Optical Lithography: Exploiting Entanglement to Beat the Diffraction Limit

Classical optical lithography is diffraction limited to writing features of a size λ/2 or greater, where λ is the optical wavelength. Using nonclassical photon-number states, entangled N at a time, we show that it is possible to write features of minimum size λ/\(2N\) in an N-photon absorbing substrate. This result allows one to write a factor of N² more elements on a semiconductor chip. A factor of N = 2 can be achieved easily with entangled photon pairs generated from optical parametric down-conversion. It is shown how to write arbitrary 2D patterns by using this method.