23 December 2004 Entanglement beats the diffraction limit
The experiment carried out by an ICFO researcher has been selected as a Highlight of the year 2004 by the Institute of Physics A new technique for producing multi-photon entangled states has been recognized by the Institute of Physics as one of the \"Highlights of the year\" for 2004. The technique, which makes it possible to break the diffraction limit and build super-high resolution interferometers was developed by ICFO researcher Morgan Mitchell with Jeff Lundeen and Aephraim Steinberg of the University of Toronto. The work was published in the 13 May 2004 issue of Nature.

In situations such as microscopy or optical lithography, diffraction limits the size of structures that can be seen or written to about half a wavelength. This limit applies to classical waves and to independent photons, but not to groups of entangled photons. Using linear optics and post-selection, Mitchell and co-workers demonstrated a new technique for producing diffraction-beating entangled photons. With a polarization interferometer they demonstrated super-resolution, beating the classical limit by a factor of three.