We experimentally demonstrate that the quantum entanglement between amplitude and phase quadratures of optical modes produced from a nondegenerate optical parametric amplifier (NOPA) can be enhanced and manipulated phase sensitively by means of another NOPA. When both NOPAs operate at deamplification, the entanglement degree is increased at the cavity resonance of the second NOPA. When the first NOPA operates at deamplification and the second one at amplification, the spectral features of the correlation variances are significantly changed. The experimental results are in good agreement with the theoretical expectation.
© 2010 Optical Society of America
Original Manuscript: November 30, 2009
Revised Manuscript: January 26, 2010
Manuscript Accepted: January 29, 2010
Published: March 15, 2010
Yana Shang, Xiaojun Jia, Yumei Shen, Changde Xie, and Kunchi Peng, "Continuous variable entanglement enhancement and manipulation by a subthreshold Type II optical parametric amplifier," Opt. Lett. 35, 853-855 (2010)