| 摘要 |
Entanglement-based QKD systems and methods with active phase tracking and stabilization are disclosed. The method includes generating in an initial state-preparation stage (Charlie) pairs of coherent photons (P1) at a first wavelength. Second harmonic generation and spontaneous parametric downconversion are used to generate entangled pairs of photons (P5) having the first wavelength-State detection stages (Alice and Bob) optically coupled to Charlie receive respective entangled photons from Charlie. The relative phase delays of the entangled photons are tracked using reference optical signals (P3) generated by Charlie and having the same wavelength as the entangled photons. Classical detectors (132A, 132B) detect the reference signals while single-photon detectors (130A, 130B) and a control unit (control unit C) generates an phase-correction signal that maintains the relative phases of the three phase delay loops (40, 100A,100B ) via adjustable phase-delay elements (MA, MB).
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