摘要： 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. 其他題名： Phys Rev Lett 出版者： United States 出版日期： 2016-11-11 出處： Physical review letters, 2016-11, Vol.117 (20), p.203601-203601, Article 203601 資源來源： American Physical Society Journals (APS) 識別號： ISSN: 0031-9007 識別號： EISSN: 1079-7114 識別號： DOI: 10.1103/PhysRevLett.117.203601 識別號： PMID: 27886497
