ExpGysBb84

Tier B: Gobby-Yuan-Shields 2004, BB84-WCP measured over 122 km

8/8 passed in 8ms

Test	What it does	Result
test_gys_dark_floor	Their "less than 0.4%" dark and stray share at 65 km is 0.374% at their alpha = 0.2; the fitted 0.21 gives 0.434%, under 0.5%.	✅ pass
test_gys_pns_reading	Their ~50 km photon-splitting limit under Brassard-Lutkenhaus-Mor-Sanders: untrusted fails everywhere, trusted gives 63.3 km, trusted with sifting 49.0 km at alpha = 0.21 and 51.4 km at 0.20.	✅ pass
test_gys_qber	The fitted e_mod band gives 8.60%-8.94% QBER at 122 km, bracketing their measured 8.9%.	✅ pass
test_gys_short_deficit	Declared miss: the collection factor is 0.936 at 4.4 km against 0.655 at 101 and 122 km, from polarisation drift the paper names and qkd does not model.	✅ pass
test_gys_sift_ladder	Their 23.4 and 9.2 bit/s sifted rates give a ratio of 2.5435 against the model's 2.5473, and collection factors 0.6544 and 0.6554, both below unity.	✅ pass
test_gys_tabulation	Ma, Qi, Zhao and Lo's GYS parameter set is this hardware: Y0 = 1.7e-6 is 2 P_e, and e_detector = 3.3% is the QBER plateau at 4.4 km.	✅ pass
test_gys_three_ways	Visibility, sifted-rate ratio and QBER invert to alpha = 0.20826, 0.20941 and 0.20974-0.21211 dB/km, a 1.9% spread inside [0.20, 0.22].	✅ pass
test_gys_visibility	Visibility at 122 km is 87.89% against their measured 88.4%, and inverting it gives alpha = 0.2083 dB/km inside [0.20, 0.22].	✅ pass