Large Cross-Phase Modulations at the Few-Photon Level

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 wi...

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Published inPhysical review letters Vol. 117; no. 20; p. 203601
Main Authors Liu, Zi-Yu, Chen, Yi-Hsin, Chen, Yen-Chun, Lo, Hsiang-Yu, Tsai, Pin-Ju, Yu, Ite A, Chen, Ying-Cheng, Chen, Yong-Fan
Format Journal Article
LanguageEnglish
Published United States 11.11.2016
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Summary: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 laser beams. With this scheme, we observe a π-level phase shift with two pulses, both consisting of eight photons in cold rubidium atoms. Such a novel scheme provides a simple route to generate strong interactions between photons and may have potential applications in all-optical quantum signal processing.
ISSN:1079-7114
DOI:10.1103/PhysRevLett.117.203601