Effects of squeezing on quantum nonlocality of superpositions of coherent states

Abstract

We analyze effects of squeezing upon superpositions of coherent states (SCSs) and entangled coherent states (ECSs) for Bell-inequality tests. We find that external squeezing can always increase the degrees of Bell violations, if the squeezing direction is properly chosen, for the case of photon parity measurements. On the other hand, when photon on/off measurements are used, the squeezing operation can enhance the degree of Bell violations only for moderate values of amplitudes and squeezing. We point out that a significant improvement is required over currently available squeezed SCSs in order to directly demonstrate a Bell-inequality violation in a real experiment.

7 pages, 4 figures, accepted for publication in Phys. Rev. A

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• Entangled coherent states versus entangled photon pairs for practical quantum information processing
• Efficient noiseless linear amplification for light fields with larger amplitudes
• Bell inequality tests using asymmetric entangled coherent states in asymmetric lossy environments
• Bell inequality test with entanglement between an atom and a coherent state in a cavity
• Implementation of traveling odd Schr$\ddot{o}$dinger cat states in circuit-QED
• Parity-Swap State Comparison Amplifier for Schrödinger Cat States