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arXiv · 2601.05558

Narrowband four-photon states from spontaneous four-wave mixing

Yifan Li·Justin Yu Xiang Peh·Chang Hoong Chow·Boon Long Ng·Vindhiya Prakash·Christian Kurtsiefer
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Abstract

We observe time-correlated four photons within a correlation window of 20ns from spontaneous four-wave mixing via a double-Lambda scheme in a cold cloud of Rb-87 atoms. In contrast to high-power pulsed pumping of chi^(2) nonlinear processes in crystals, our scheme generates correlated four-photon states by direct continuous-wave pumping at nominal powers. We verify the presence of genuinely correlated four-photon states over accidentals by higher-order intensity cross-correlation measurements and accidental subtraction. We infer a time-correlated four-photon generation rate of 2.5(4)x10^6 counts per second close to saturation. The photons produced are near-resonant with atomic transitions, and have a bandwidth in the order of MHz, making them readily compatible with quantum networking applications involving atoms.

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Yifan Li, Justin Yu Xiang Peh, Chang Hoong Chow, Boon Long Ng, Vindhiya Prakash, Christian Kurtsiefer. 2026-01-09. Narrowband four-photon states from spontaneous four-wave mixing. https://arxiv.org/abs/2601.05558

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