Simple protocol for secure decoy-state quantum key distribution with a loosely controlled source

The method of decoy-state quantum key distribution (QKD) requests different intensities of light pulses. Existing theory has assumed exact control of intensities. Here we propose a simple protocol which is secure and efficient even there are errors in intensity control. In our protocol, decoy pulses and signal pulses are generated from the same father pulses with a two-value attenuation. Given the upper bound of fluctuation of the father pulses, our protocol is secure provided that the two-value attenuation is done exactly. We propose to use unbalanced beam-splitters for a stable attenuation. Given that the intensity error is bounded by $\pm5$, with the same key rate, our method can achieve a secure distance only 1 km shorter than that of an ideal protocol with exactly controlled source

Observation of clinical efficacy of pattern scan laser photocoagulation on diabetic retinopathy

AIM: To evaluate the clinical efficacy of pattern scan laser photocoagulation(Pascal)on proliferative diabetic retinopathy(PDR).<p>METHODS: A total of 93 patients with retinopathy(186 eyes)were randomly divided into treatment group(96 eyes of 48 patients)who treated with panretinal photocoagulation(PRP)using Pascal at one time and control group(90 eyes of 45 patients)who treated with PRP using multi-wavelength krypton laser in 4-5 times. The visual acuity, FFA, OCT, visual field will be evaluated of each patient before and after the treatment.<p>RESULTS: The visual acuity findings were stated as below: the overall effective rate of visual acuity in treatment group is 85.4% while it is 82.2% in control group. The overall effective rate in two groups has no significant difference. The retinal sensitivity has no significant decrease in the treatment group while which decreased significantly in the control group.<p>CONCLUSION: The clinical efficacy of Pascal on treating the PDR is better than which of the regular argon laser. The field of vision has no significant narrowed after the Pascal treatment which can efficiently shorten the length of treatment and reduce the pain sensation