arXiv:quant-ph/0703132
Elaboration of linear-optical implementations of Deutsch algorithm utilizing entanglements
Koji Nagata, Sangkyung Lee, Jaewook Ahn
Abstract
We propose multiple implementations of linear-optical processing of Deutsch algorithm using entangled state. Recently Oliveira {\\it et al.} [ J. Opt. B \\textbf{7}, 288 (2005) ] experimentally demonstrated the use of polarization and transverse spatial modes of the electromagnetic field as qubits for Deutsch algorithm, in which three Hadamard gates and a function are used. In our new implementations, the answer to the Deutsch problem is successfully determined even without the use of Hadamard gates. Instead, we use a polarization-momentum entangled bi-photon state. Coincidence measurements of photon arrivals coupled with polarization state analyzers identify answers to Deutsch problem. The entanglement-witness analysis is applied to validate the fidelity or the performance of the schemes.