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Journal of Modern Optics

Preparing entangled states of two atoms through the intensity-dependent interaction with the two-mode squeezed vacuum

Fuli Li, Peng Peng, Zhang‐qi Yin

Published Jun 30, 2006• 5 citations

Abstract

Two four-level atoms resonantly interacting with a two-mode squeezed vacuum field through the intensity-dependent Jaynes–Cummings-like model are considered. It is shown that the atoms can evolve into pure entangled states at certain time. Moreover, the pure entangled states can probabilistically be projected onto extremely entangled states by quantum jump technique. It is shown that the success probability monotonously increases with increasing degree of squeezing without any decoherence processes. However, it is found that if decoherence processes such as atomic spontaneous emission and photon leakage out of the cavity take place, the total success probability first increases but then decreases with increasing degree of squeezing and finally approaches zero as the squeezing becomes stronger and stronger. Therefore, the high degree of squeezing in the initial state of the cavity field is not always helpful for a high probability of creating extremely entangled states when spontaneous emission and cavity decay exist. Given spontaneous emission and photon leakage rates, there is an optimal squeezing degree for which the total success probability becomes maximum.

DOI: 10.1080/09500340600798900

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The evolution of the entanglement degree of two-mode fields and atom with the intensity-dependent coupling is investigated using von Neumann entropy. The results for the initial fields in both coherent states and two-mode squeezed vacuum state are calculated. The influence of the field intensity on the entropy is discussed. It is found that the field and atom are generally in maximum entanglement but subject to periodic pulsed disentanglement completely under the condition of strong initial field.

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