Conversion of Knill-Laflamme-Milburn Entanglement to Greenberger-Horne-Zeilinger Entanglement

摘要

Schemes for converting photonic polarized-entangled Knill-Laflamme-Milburn (KLM) states to Greenberger-Horne-Zeilinger (GHZ) states are proposed using weak cross-Kerr nonlinearity and X-quadrature homodyne measurement. Analyses show that the two-qubit (Bell state) and three-qubit conversion cases have very high fidelities and close-to-unity probabilities. The conversion processes are robust against photon loss. The schemes linking these two entangled states may be helpful to the study of quantum information processing based on them.