Twin-field quantum key distribution without phase post-selection based on heralded pair-coherent source

Twin-field quantum key distribution protocols and their variants break the linear key rate limit in non-relay scenarios, with without phase post-selection versions further reduce experimental complexity through simplified protocol structures. However, traditional implementations based on weak coherent source are constrained by low single-photon pulse rates and high-vacuum-state noise, limiting key rates and transmission distances. This study proposes a protocol integrating heralded pair-coherent source without phase post-selection quantum key distribution, combined with a four-intensity decoy-state method for optimized parameter estimation. Simulations demonstrate that heralded pair-coherent source without phase post-selection twin-field quantum key distribution achieves a key rate improvement of more than 10 times higher compared to weak coherent source schemes under finite data size, extends transmission distances by over 100 km and maintains robustness in high-loss channels. These breakthroughs validate its practical value for real-world medium-to-long-haul quantum communication scenarios.