Entanglement of coherent states and decoherence*

The possibility of producing entangled superpositions of strong coherent states is discussed. A recent proposal by Howell and Yeazell (2000 Phys. Rev. A 62 012102) of a device that entangles two strong coherent states is modified. It is shown that the modified scheme can generate non-classical states that violate Bell inequality. Moreover, a detailed analysis of the effect of losses and decoherence on the degree of entanglement is accomplished. It reveals the high sensitivity of the device to any disturbances and the fragility of generated states.