Experimental Twin-Field Quantum Key Distribution over 1000 km Fiber Distance.

Quantum key distribution (QKD) aims to generate secure private keys shared by two remote parties. With its security being protected by principles of quantum mechanics, some technology challenges remain towards practical application of QKD. The major one is the distance limit, which is caused by the fact that a quantum signal cannot be amplified while the channel loss is exponential with the distance for photon transmission in optical fiber. Here using the 3-intensity sending-or-not-sending protocol with the actively-odd-parity-pairing method, we demonstrate a fiber-based twin-field QKD over 1002 km. In our experiment, we developed a dual-band phase estimation and ultra-low noise superconducting nanowire single-photon detectors to suppress the system noise to around 0.02 Hz. The secure key rate is 9.53×10^{-12} per pulse through 1002 km fiber in the asymptotic regime, and 8.75×10^{-12} per pulse at 952 km considering the finite size effect. Our work constitutes a critical step towards the future large-scale quantum network.

[Expression level and clinical significance of CD44 and CD33 in 77 patients with benign lymphoadenosis of oral mucosa].

PURPOSE: To investigate the expression and clinical significance of CD44 and CD33 in benign lymphoadenosis of oral mucosa(BLOM). METHODS: From January 2017 to March 2020, seventy-seven BLOM wax blocks from the Department of Pathology of Qingdao Traditional Chinese Medicine Hospital were selected as the experimental group, and 63 cases of normal oral mucosal tissue wax blocks during the same period were selected as the control group. Immunohistochemical method was used to detect the positive expression of CD44 and CD33 in the two groups.Spearman correlation analysis was used to analyze the correlation between the positive expression of CD33 and the positive expression of CD44 in the diseased tissues of BLOM patients.The general information about patients were collected.The relationship between the expression of CD33 and CD44 in the diseased tissues of BLOM patients and the clinicopathological characteristics of BLOM patients were analyzed. SPSS 21.0 software package was used for statistical analysis of the data. RESULTS: The positive expression rates of CD33 in the control group and the experimental group were 95.24% and 63.64%, respectively, and the difference was statistically significant(P＜0.05). The positive expression rates of CD44 in the control group and the experimental group were 93.65% and 67.53%, respectively, and the difference was statistically significant(P＜0.05). The results of Spearman correlation analysis showed that the positive expression of CD33 in the diseased tissues of BLOM patients was positively correlated with the positive expression of CD44 (r=0.834, P=0.002). The expression of CD33 and CD44 in the diseased tissues of patients with BLOM were related to clinical type, degree of inflammation, presence or absence of lymphoid follicles, and lymphocyte infiltration(P＜0.05), but not related to age, gender, course of disease, location, and epithelial surface keratinization(P＞0.05). CONCLUSIONS: The positive expression rate of CD33 and CD44 in the BLOM tissues decreased, which was closely related to the clinical type, degree of inflammation, presence or absence of lymphoid follicles, and lymphocyte infiltration.