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arXiv · 1607.00818

Large Cross-Phase Modulations at the Few-Photon Level

Zi-Yu Liu·Yi-Hsin Chen·Yen-Chun Chen·Hsiang-Yu Lo·Pin-Ju Tsai·Ite A. Yu·Ying-Cheng Chen·Yong-Fan Chen
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Abstract

We demonstrate an efficient cross-phase modulation (XPM) based on a closed-loop double-Λ system. The property of the double-Λ medium can be controlled by changing the phases of the applied optical fields. This phase-dependent XPM scheme can achieve large phase modulations at low-light intensities without requiring cavities or tightly focusing of laser beams. With this scheme, we observe a π-level phase shift with two pulses both consisting of 8 photons in cold rubidium atoms. Such novel scheme provides a simple route to generate strong interactions between photons and may have potential applications in all-optical quantum signal processing.

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Zi-Yu Liu, Yi-Hsin Chen, Yen-Chun Chen, Hsiang-Yu Lo, Pin-Ju Tsai, Ite A. Yu, Ying-Cheng Chen, Yong-Fan Chen. 2016-07-04. Large Cross-Phase Modulations at the Few-Photon Level. https://doi.org/10.1103/physrevlett.117.203601

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