Abstract
Parametric single-photon sources are well suited for large-scale quantum networks due to their potential for photonic integration. Active multiplexing of photons can overcome the intrinsically probabilistic nature of these sources, resulting in near-deterministic operation. However, previous implementations using spatial and temporal multiplexing scale unfavorably due to rapidly increasing switching losses. Here, we break this limitation via frequency multiplexing in which switching losses remain fixed irrespective of the number of multiplexed modes. We use low-noise optical frequency conversion for efficient frequency switching and demonstrate multiplexing of three modes. We achieve a generation rate of 4.6 × 104 photons per second with an ultra-low g(2)(0) = 0.07 indicating high single-photon purity. Our scalable, all-fiber multiplexing system has a total loss of just 1.3 dB, such that the 4.8 dB multiplexing enhancement markedly overcomes switching loss. Our approach offers a promising path to creating a deterministic photon source on an integrated chip-based platform.
Highlights
Parametric single-photon sources are well suited for large-scale quantum networks due to their potential for photonic integration
There have been a number of promising demonstrations of multiplexed sources using the spatial and temporal degrees of freedom of a photon[26,27,28,29,30,31,32]. For both spatial and temporal multiplexing, switching losses increase with the number of modes N, which deteriorates enhancement achieved from multiplexing beyond a few modes
We show that Bragg scattering four-wave mixing (BS-FWM) is efficiently tunable over a large bandwidth of more than 1 THz and our system can be scaled to include a large number of frequency modes, which is critical for deterministic photon generation using multiplexing
Summary
Parametric single-photon sources are well suited for large-scale quantum networks due to their potential for photonic integration. Parametric sources can be fully integrated onto monolithic CMOS-compatible platforms to generate narrow band entangled photons with high brightness[17,18,19] These sources are fundamentally limited by multi-photon generation, resulting in probabilistic operation with a maximum heralding efficiency of 25% from a single source. We present a proof-ofprinciple demonstration of frequency multiplexing using three frequency modes in an entirely fiber-based setup that leverages on low-loss off-the-shelf dense wavelength division multiplexing (DWDM) components With this low-loss and low-noise setup we achieve generation rates of 46 kHz multiplexed photons with coincidences-to-accidentals ratio exceeding 100 and g(2)(0) of 0.07. We show that BS-FWM is efficiently tunable over a large bandwidth of more than 1 THz and our system can be scaled to include a large number of frequency modes, which is critical for deterministic photon generation using multiplexing
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