Quantum-information processing for a coherent superposition state via a mixedentangled coherent channel

TLDR

Entangled two‑mode coherent states are examined in a $2\times2$ Hilbert space, noting that environmental vacuum causes partial but not complete loss of entanglement. The study investigates teleporting a coherent superposition state using a mixed entangled coherent channel. An entanglement concentration scheme based on joint Bell‑state measurements is developed, and the teleportation protocol employs this mixed channel. Higher initial coherent amplitude accelerates entanglement decay, and the resulting decohered channel yields teleportation fidelity below the classical threshold of 2/3, rendering it ineffective.

Abstract

An entangled two-mode coherent state is studied within the framework of $2\times 2$ dimensional Hilbert space. An entanglement concentration scheme based on joint Bell-state measurements is worked out. When the entangled coherent state is embedded in vacuum environment, its entanglement is degraded but not totally lost. It is found that the larger the initial coherent amplitude, the faster entanglement decreases. We investigate a scheme to teleport a coherent superposition state while considering a mixed quantum channel. We find that the decohered entangled coherent state may be useless for quantum teleportation as it gives the optimal fidelity of teleportation less than the classical limit 2/3.