Variance 〈(δ<em>X</em><sub>+</sub>)<sup>2</sup>〉 versus <em>r</em><sub>1</sub> for the fixed collective phase Φ = 0

2013-09-05T00:00:00Z (GMT) by Qing Xu Xiangming Hu
<p><strong>Figure 5.</strong> Variance 〈(δ<em>X</em><sub>+</sub>)<sup>2</sup>〉 versus <em>r</em><sub>1</sub> for the fixed collective phase Φ = 0. The other parameters are <em>q</em> = (0, 0.2, 0.5, 1, 5, 10). (a) <em>s</em> = 0.5, (b) <em>s</em> = 1, (c) <em>s</em> = 2, and (d) <em>s</em> = 5. The curves for <em>q</em> = (1, 5, 10) can hardly be distinguished. The variance drops below the standard quantum limit 1 in a wide range of parameters. This indicates the existence of the two-mode squeezing and entanglement under loose conditions.</p> <p><strong>Abstract</strong></p> <p>We show that it is possible to use an atom–cavity reservoir to prepare the two-mode squeezed and entangled states of a hybrid system of an atomic ensemble and an optical field, which do not directly interact with each other. The essential mechanism is based on the combined effect of a two-mode squeezing interaction and a beam–splitter interaction between the system and the reservoir. The reservoir mechanism is important for quantum networking in that it allows an interface between a localized matter-based memory and an optical carrier of quantum information without direct interaction.</p>