Quantum dot source-based twin-field quantum key distribution

Photon-number superposition states represent a powerful resource for quantum information processing and can now be deterministically generated using QD platforms. Here, we propose a twin-field quantum fey distribution (TF-QKD) protocol that employs photon-number superposition states of the form $\sqrt{1 - t}|0\rangle + e^{i\phi} \sqrt{t}|1\rangle$, prepared by a microcavity-enhanced QD system. Numerical simulations show that our protocol surpasses previously proposed TF-QKD schemes by using laser in terms of both secret key rate and achievable distance. It breaks the repeaterless bound and enables secure communication over distances exceeding 240 km, even under realistic system conditions. Most importantly, our protocol can be directly implemented using existing QD platforms, demonstrating a practical pathway toward high-performance, solid-state-based long-distance TF-QKD. Our work highlights the potential of advanced quantum communication protocols utilizing non-classical quantum light sources in quantum networks.