Experimentally feasible generation protocol for polarized hybrid entanglement

Abstract

We propose a scheme to generate polarized hybrid entanglement in the form of $|H\ensuremath{\rangle}|\ensuremath{\alpha}\ensuremath{\rangle}+|V\ensuremath{\rangle}|\ensuremath{-}\ensuremath{\alpha}\ensuremath{\rangle}$ by interference between a superposition of coherent states and a polarization entangled photon pair. In the scheme two sets of interferences with perpendicular polarizations are designed to erase ``which path'' information. The joint output fields of the two sets of interferences are used to herald the generation of the polarized hybrid entanglement. The advantage of the protocol is its experimental feasibility since it not only realizes effective interference but also retains the polarization information in the output fields of interferences. We also analyze the effect of imperfect experimental conditions on the generated hybrid state, including inefficiency on-off single-photon detectors with dark counts and available approximate resource states. The theoretical analysis shows that the fidelity of the heralded hybrid state with small amplitude can be maintained at a high level under actual experimental conditions.