Frequency conversion of an entangled state (6 pages)

Wei‐Bin Yan, Zhong-Ju Liu, Ling Zhou

Toshiki Kobayashi, Atsushi Yabushita

J. C. Martínez

Aihong Tan, Xiaojun Jia, Changde Xie

The quantum characteristics of sum-frequency process in an optical cavity with an input signal optical beam, which is a half of entangled optical beams, are analyzed. The calculated results show that the quantum properties of the signal beam can be maintained after its frequency is conversed during the intracavity nonlinear optical interaction. The frequency-conversed output signal beam is still in an entangled state with the retained other half of the initial entangled beams. The resultant quantum correlation spectra and the parametric dependences of the correlations on the initial squeezing factor, the optical losses and the pump power of the sum-frequency cavity are calculated. The proposed system for the frequency conversion of the entangled state can be used in quantum communication network and the calculated results can provide direct references for the design of experimental systems.

Xiaohui Qian

Anshou Zheng, Xin-you Lü, Jibing Liu

A single-photon frequency conversion process with a Sagnac interferometer (Bradford et al 2012 Phys. Rev. Lett. 108 103902 and Bradford and Shen 2012 Phys. Rev. A 85 043814) is described by the input–output formalism. The result shows that a perfect frequency conversion can be obtained in an appropriate parameter regime via constructive interference. Based on the frequency-conversion process, an alternative scheme is provided for the generation of entanglement between distant particles including two-body entanglement and multi-body Greenberger–Horne–Zeilinger entanglement. We study the effect of the parameters' deviation and spontaneous decay of the excited state and waveguide mode on the transmission amplitudes, and also on the frequency-conversion efficiency. In addition, the influence of the experimental parameters on the fidelity of the entangled state is discussed.