Photon-loss-tolerant Zeno controlled-SIGN gate

Abstract

We model an optical implementation of a controlled-SIGN gate that makes use of the quantum Zeno effect [Franson et al., Phys. Rev. A 70, 062302 (2004)] in the presence of photon loss. Gate operation is severely affected. However, we show that by using photon loss codes proposed for linear optical quantum computation (LOQC), performance is greatly enhanced, outperforming LOQC equivalents. The technique can be applied to other types of nonlinearities, making the implementation of nonlinear optical gates much more attractive.