Complete and faithful hyperentangled-Bell-state analysis of photon systems using a failure-heralded and fidelity-robust quantum gate.

Hyperentangled-Bell-state analysis (HBSA) represents a key step in many quantum information processing schemes that utilize hyperentangled states. In this paper, we present a complete and faithful HBSA scheme for two-photon quantum systems hyperentangled in both the polarization and spatial-mode degrees of freedom, using a failure-heralded and fidelity-robust quantum swap gate for the polarization states of two photons (P-SWAP gate), constructed with a singly charged semiconductor quantum dot (QD) in a double-sided optical microcavity (double-sided QD-cavity system) and some linear-optical elements. Compared with the previously proposed complete HBSA schemes using different auxiliary tools such as parity-check quantum nondemonlition detectors or additional entangled states, our scheme significantly simplifies the analysis process and saves the quantum resource. Unlike the previous schemes based on the ideal optical giant circular birefringence induced by a single-electron spin in a double-sided QD-cavity system, our scheme guarantees the robust fidelity and relaxes the requirement on the QD-cavity parameters. These features indicate that our scheme may be more feasible and useful in practical applications based on the photonic hyperentanglement.

Implementation of single-photon quantum routing and decoupling using a nitrogen-vacancy center and a whispering-gallery-mode resonator-waveguide system.

Quantum router is a key element needed for the construction of future complex quantum networks. However, quantum routing with photons, and its inverse, quantum decoupling, are difficult to implement as photons do not interact, or interact very weakly in nonlinear media. In this paper, we investigate the possibility of implementing photonic quantum routing based on effects in cavity quantum electrodynamics, and present a scheme for single-photon quantum routing controlled by the other photon using a hybrid system consisting of a single nitrogen-vacancy (NV) center coupled with a whispering-gallery-mode resonator-waveguide structure. Different from the cases in which classical information is used to control the path of quantum signals, both the control and signal photons are quantum in our implementation. Compared with the probabilistic quantum routing protocols based on linear optics, our scheme is deterministic and also scalable to multiple photons. We also present a scheme for single-photon quantum decoupling from an initial state with polarization and spatial-mode encoding, which can implement an inverse operation to the quantum routing. We discuss the feasibility of our schemes by considering current or near-future techniques, and show that both the schemes can operate effectively in the bad-cavity regime. We believe that the schemes could be key building blocks for future complex quantum networks and large-scale quantum information processing.

[Investigation of HIV and syphilis infection status and risk sexual behavior among men who have sex with men in four cities of China].

OBJECTIVE: To investigate HIV and treponema pallidum infection status, risky sexual behavior among men who have sex with men (MSM) and its impact factors in China. METHODS: Snowball sampling was used to recruit subjects from April to August in 2008 in Beijing, Harbin, Zhengzhou and Chengdu city. Serological test of HIV and treponema pallidum were conducted and a questionnaire survey was undertaken among subjects. The questionnaire included social demographics, characteristics of sexual partners and sexual behaviors. RESULTS: A total of 1693 subjects was enrolled in present study, which included 1390 MSM/M (82.1%) and 303 MSMW (17.9%). The infection rate of HIV among MSM/M and MSMW subjects were 7.0% (97/1390) and 6.6% (20/303), respectively. The infection rate of treponema pallidum among MSM/M and MSMW subjects were 11.9% (166/1390) and 13.2% (40/303), respectively. The proportions of MSM/M subjects who never used or sometimes used condoms when having same-sex anal intercourse in recent 6 months were 8.6% (120/1390), 45.3% (630/1390), respectively. The according proportions among MSMW subjects were 10.2% (31/303), 44.6% (135/303), respectively. Among MSM/M subjects, the risk factors of risk sexual behaviors included having less than 6 sexual partners (OR = 6.03, 95%CI: 2.54 - 14.28), no same-sex regular sexual partner (OR = 2.18, 95%CI: 1.30 - 3.65), no same-sex casual sexual partner (OR = 2.90, 95%CI: 1.79 - 4.71), T-pattern only during anal intercourse (OR = 1.64, 95%CI: 1.13 - 2.37) or P-pattern only (OR = 1.58, 95%CI: 1.04 - 2.41). Among MSMW subjects, the risk factors of same-sex risk sexual behaviors included having less than 6 sexual partners (OR = 12.95, 95%CI: 2.38 - 70.52), no same-sex regular sexual partners (OR = 0.42, 95%CI: 0.21 - 0.85), never used condom during heterosexual intercourse (OR = 3.53, 95%CI: 1.48 - 8.42). CONCLUSION: The infection rate of HIV and treponema pallidum among MSM subjects were quite high, and the same-sex risk sexual behaviors among MSM subjects were ubiquity, whose risk factors including having less than six of sexual partners, no same-sex casual sexual partner, T-pattern or P-pattern only during anal intercourse and never used condemn during heterosexual intercourse among MSMW subjects no same-sex regular partner was a risk factor in MSMS population, while having same-sex regular partners was a risk factor in MSMW population.

[Effect of superparamagnetic iron oxide on differentiation of rat bone marrow stem cells into chondrocytes in vitro].

OBJECTIVE: To observe the effect of superparamagnetic iron oxide (SPIO) on the differentiation of rat bone marrow stem cells (BMSCs) into chondrocytes in vitro and explore the possible mechanism. METHODS: CCK8 assay was performed to examine the cytotoxicity of SPIO (1 and 5 µg/mL) on cultured SD rat BMSCs. Prussian blue staining and fluorescence excitation assay were used to assess the binding of the SPIO to BMSCs after the cells had been cultured in chondrocytes-induced medium in the presence of SPIO (1 and 5 µg/mL) for 9 days. The mRNA levels of COL2 α2, aggrecan and MMP13 in the cell culture were examined using Q-PCR, and the chondrogenic differentiation of the BMSCs was analyzed using alcian blue staining and immunofluorescence staining for COL2 α2. The protein levels of COL2 α2, aggrecan, MMP13, Ihh and PTHrP in the cells were examined using Western blotting. RESULTS: CCK8 assay showed no significant toxicity of SPIO on BMSCs. Compared with the control cells, the cells cultured in the presence of SPIO showed increased expressions of COL2 α2 and aggrecan and decreased expression of MMP13 at both mRNA and protein levels with also significantly increased expressions of Ihh and PTHrP proteins. CONCLUSION: SPIO can promote the differentiation of rat BMSCs into chondrocytes and up-regulate the Ihh/PTHrP signal pathway, suggesting the potential of SPIO as a new therapeutic agent for chondrocyte-related diseases.

[Prevalence of HIV infection and sexual behaviors with both men and women among currently married men who have sex with men].

OBJECTIVE: To find out the status of HIV infection, sexual behaviors with both men and women as well as condom use among currently married men who have sex with men (MSM) so as to document for HIV intervention targeting this sub-population, in Beijing, Chengdu, Harbin and Zhengzhou cities. METHODS: "Snowballing" sampling method was used to recruit subjects in four cities. Participants were investigated by anonymous questionnaire containing demographics, sexual orientation, both homosexual and heterosexual behaviors and condom use during the past 6 months. Blood samples from participants were used to test HIV antibodies. RESULTS: Of the 858 participants for four cities, the average age was 38.3 (SD=9.1) years. 36.7% of them had completed the junior high school or under. The percentage of participants who identified themselves as homosexual, bisexual, and heterosexual or undecided were 40.9%, 54.3% and 4.8%, respectively. The overall HIV prevalence was 8.0%, and among four cities the HIV prevalence in Chengdu was the highest (13.3%). Results from the Multiple logistic regression analysis showed that never used condoms when having anal sex with men during the past 6 months among participants who did not have a city residential card, identifying himself as having homosexual orientation, living in Harbin, having first anal sex experience before 18 years of age the range of OR value was 1.5-2.1. In addition, the factors associated with never using condoms in vaginal sex with women during the past 6 months were as follows: being over 46 years old, not having a city residential card, living in Beijing, identifying himself as heterosexual orientated or with unknown sexual orientation, never using condoms in anal sex with men during the past 6 months, the range of OR value was 1.7-5.9. CONCLUSION: The prevalence of HIV infection seemed to be quite high among those currently married MSM. High rates of unprotected homosexual and heterosexual behaviors might accelerate the spreading of HIV from currently married MSM to their wives.