Abstract Quantum communication networks rely on quantum cryptographic protocols including quantum key distribution (QKD) based on single photons. A critical element regarding the security of QKD protocols is the photon number coherence (copyright). i. e. https://www.alarecre.com/Looney-Tunes-Marvin-the-Martian-Big-Head-Galaxy-S23-Waterproof-Case-p116784/