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Entangled Photon Triplets Using Lithium Niobate Nanophotonics

Ayantika Sengupta, Nathan Harper, Emily Hwang, Scott K. Cushing

Published Jan 1, 2026• 0 citations
Publisher

Abstract

We integrate two cascaded downconverters on thin-film lithium niobate to realize a triplet source with 130 kHz/mW efficiency, improving previous sources by an order of magnitude and advancing toward MHz triplet rates for quantum applications.
DOI
10.1364/cleo_fs.2026.ftu1d.4

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Multiphoton states are needed for quantum communication and computation. Multiphoton states are significantly more difficult to generate than one- and two-photon states because two individual down-conversion processes must be cascaded. Only efficiencies of <100<100<100 Hz/mW have been reported to date. We integrate two down-converters on the same thin-film lithium niobate waveguide, significantly enhancing the cascaded process efficiency to 237±36237 \pm 36237±36 kHz/mW. The measured 4.4×10−54.4 \times 10^{-5}4.4×10−5 probability of the second down-converter, which sets the limit on detectable triplet rates, exceeds those of previous triplet sources by an order of magnitude and demonstrates a path towards MHz rates of triplets for quantum applications.
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