Preparing, linking, and unlinking cluster-type polarization-entangled states by integrating modules

Abstract

Integrating the modules of the controlled phase-flip gate, the distributed entanglement gate, and the simplified entanglement gate, we propose schemes for preparing, linking, and unlinking standard cluster-type polarization-entangled states, which are achieved by performing different operations for cluster-type states consisting of even and odd photons, in company with Hadamard gate operations and other single-photon operations.Mediated by weak cross-Kerr nonlinear interactions, two individual photons interact with each other depending on the assistance of the coherent state in Kerr media.Exploiting homodyne measurement and polarization beam splitters, the photon paths take on a certain ambiguity and photons entangle together in the polarization mode.Assisted by a classical feed-forward, these aforementioned modules can be realized with an efficiency approaching unity.Employing the module of the controlled phase-flip gate, standard even-and odd-photon cluster-type states can be prepared, which are distinguished by the different photons performed by Hadamard gate operations.Linking two or more standard cluster-type states, a new standard cluster-type state can be produced after combination of the module of the controlled phase-flip gate and Hadamard gate operations.Dividing, truncating, or pinching a multi-photon cluster-type state can be accomplished by applying the module of the controlled phase-flip gate and single-photon operations including Hadamard gate operations.. . . . . . .