Quantum cryptography harnesses quantum light, in particular single photons, to provide security guarantees that cannot be reached by classical means. For each cryptographic task, the security feature of interest is directly related to the photons’ non-classical properties. Quantum dot-based single-photon sources are remarkable candidates, as they can in principle emit deterministically, with high brightness and low multiphoton contribution. Here, we show that these sources provide additional security benefits, thanks to the tunability of coherence in the emitted photon-number states. We identify the optimal optical pumping scheme for the main quantum-cryptographic primitives, and benchmark their performance with respect to Poisson-distributed sources such as attenuated laser states and down-conversion sources. In particular, we elaborate on the advantage of using phonon-assisted and two-photon excitation rather than resonant excitation for quantum key distribution and other primitives. The presented results will guide future developments in solid-state and quantum information science for photon sources that are tailored to quantum communication tasks.

量子密码术利用量子光，特别是单光子，来提供传统方法无法达到的安全保证。对于每个加密任务，感兴趣的安全特征与光子的非经典属性直接相关。基于量子点的单光子源是出色的候选者，因为它们原则上可以确定性地发射，具有高亮度和低多光子贡献。在这里，我们展示了这些来源提供了额外的安全优势，这要归功于发射的光子数状态的相干性的可调性。我们确定了主要量子密码原语的最佳光泵浦方案，并针对衰减激光状态和下转换源等泊松分布源对它们的性能进行了基准测试。尤其是，我们详细阐述了使用声子辅助和双光子激发而不是共振激发来进行量子密钥分配和其他原语的优势。所呈现的结果将指导针对量子通信任务量身定制的光子源的固态和量子信息科学的未来发展。