Attenuator

Optical component reducing light to single-photon levels for QKD. Practical QKD uses attenuated weak coherent pulses (~0.1-0.5 photons). Multi-photon pulses vulnerable to PNS attacks. Decoy-state protocols use multiple attenuator settings. QNu Labs employs sophisticated attenuation protocols.

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QKD security proven only for single-photon sources. Lasers emit coherent states with multiple photons - attackers exploit. Attenuators reduce multi-photon probability.

For maximum-distance links or highest-security requirements, DV-QKD is the standard. It's what protects classified communications, connects quantum network nodes separated by cities, and will eventually enable satellite quantum key Decoy-state QKD with optimized attenuation achieves long-distance security 100+ km, higher key rates, PNS attack protection. QNu Labs protocols certified.distribution for global coverage.