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Optics Letters

Silicon bidirectional-pumping-assisted multiplexing single-photon sources with high count rates

Baojie Hou, Haoran Ma, Zichao Zhao, Qishen Liang, Fanjie Ruan, Qikai Huang, Donghui Chen, Bin Zhang, Tingge Dai, Yuehai Wang, Huihui Zhu, Jianyi Yang

Published Mar 2, 2026• 0 citations
Publisher

Abstract

The non-deterministic nature of photon sources poses a fundamental challenge to scaling single-photon quantum processors. While multiplexing in space, time, and frequency can enhance heralding efficiency, key bottlenecks remain in the efficiency of the on-chip resource unit and the speed of the external control system. Here, we demonstrate a high-count-rate, spatially multiplexed single-photon source on a silicon chip. By implementing a bidirectional pumping scheme, our architecture halves the number of required photon sources, creating a compact, optimized unit for future large-scale multiplexing sources. In addition, we implement a control system based on a Random-Access Memory First-In-First-Out module to improve the count rate limitation. Experimental results demonstrate a coincidence count rate gain of 1.67 under both pulsed and continuous-wave pumping regimes in our system. This work provides a scalable unit design and a robust control strategy for high-rate quantum photonic circuits.

DOI
10.1364/ol.586532

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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.
Integrated silicon micro-ring resonator (MRR) has been widely used as on-chip single photon source. In this paper, we introduce an approach to generate frequency-degenerate photons by bidirectionally pumping an add-drop micro-ring resonator (MRR) within a Sagnac loop configuration. This scheme facilitates the concurrent generation of photon pairs from both clockwise (CW) and counterclockwise (CCW) directions, transforming a single MRR into a dual-source system. Through CMOS fabrication techniques, we realized the proposed device and conducted measurements of key parameters including the single side count rate (SSCR), coincidence count rate (CCR), and coincidence-to-accidental coincidence ratio (CAR) for both directional outputs. Notably, the CCRs exhibit remarkable similarity between the two sources, reaching approximately 550 Hz at an waveguide power of 0.59 mW. Furthermore, we observed a differential CAR, with the CCW direction yielding a lower value compared to the CW direction, with estimated maxima of 161 and 387, respectively. These findings underscore the viability of utilizing a singular MRR as a dual-source entity. Additionally, we outline the design of an on-chip structure for heralded Hong-Ou-Mandel (HOM) interference, necessitating 4-fold coincidences.Our work holds the promise of advancing the realm of large-scale integrated quantum photonic chips.