Coherent-state linear optical quantum computing gates using simplified diagonal superposition resource states

A. P. Lund, T. C. Ralph
2005 Physical Review A. Atomic, Molecular, and Optical Physics  
In this paper we explore the possibility of fundamental tests for coherent state optical quantum computing gates [T. C. Ralph, et. al, Phys. Rev. A \textbf{68}, 042319 (2003)] using sophisticated but not unrealistic quantum states. The major resource required in these gates are state diagonal to the basis states. We use the recent observation that a squeezed single photon state ($\hat{S}(r) \ket{1}$) approximates well an odd superposition of coherent states ($\ket{\alpha} - \ket{-\alpha}$) to
more » ... ket{-\alpha}$) to address the diagonal resource problem. The approximation only holds for relatively small $\alpha$ and hence these gates cannot be used in a scaleable scheme. We explore the effects on fidelities and probabilities in teleportation and a rotated Hadamard gate.
doi:10.1103/physreva.71.032305 fatcat:e73nlu5oc5fhzlatvmofev2rrm