Integrated photon-pair sources on periodically poled thin-film lithium tantalate

Chip-integrated photon-pair sources based on spontaneous parametric down-conversion (SPDC) have emerged as a promising solution for scalable quantum light generation. Thin-film lithium tantalate (TFLT) is a compelling χ⁽²⁾ platform, combining strong nonlinearity with a high optical-damage threshold, weak photorefractive response, and ferroelectricity that enables quasi-phase matching. However, SPDC-based photon-pair generation on TFLT has not yet been demonstrated. Here, we combine high-quality periodic poling with low-loss nanophotonic waveguides to realize photon-pair sources on TFLT in both traveling-wave and resonant configurations. In periodically poled straight waveguides, we achieve broadband photon-pair generation with high efficiency $2.1 GHz mW^-1$ and coincidence-to-accidental ratio up to $3.8times10⁵$. We further confirm high-purity single-photon operation via heralded second-order correlation $g^{(2}_\mathrm{H}(0) = 0.0018 \pm 0.0002) and high-fidelity time-energy entanglement through Franson interference \(visibility of98.9 \pm 0.5%\). In periodically poled racetrack resonators, we map out a broad quantum frequency comb spanning the telecom C- and L-bands. By isolating individual frequency-correlated pairs, we measure a high spectral brightness of11 \mathrm{GHz} \mathrm{mW}^{-1} \mathrm{GHz}^{-1}. These results are competitive with the state of the art acrossχ^{(2)}$ integrated platforms, positioning TFLT as a strong contender for integrated quantum light sources, with applications in wavelength-multiplexed quantum communications and photonic quantum information processing.