Light is one of the most promising carriers of quantum information. It is robust against decoherence because it does not interact with stray electric and magnetic fields and passes unscathed through transparent matter.
But this prized robustness is also a serious limitation. Photons do not easily interact with each other so processing the information they carry is tricky.
In recent years, however, physicists have worked out how to make photons interact using interferometers and to carry out quantum computations using the output of one interferometer as the input for another. via technology review
December 19, 2011
