Microwave single-photon detection is one of the critical tasks for the implementation of the desired microwave quantum information processing. Given the detection efficiency of the demonstrated microwave single-photon detector is still very limited, here, we propose a nonreciprocity detector array to implement high-efficiency detection of a single itinerant microwave photon, transported along a one-dimensional waveguide. We show that different from the reciprocity array with more than 20 atomic detectors [Romero et al., Phys. Rev. Lett. 102, 173602 (2009)] for ideal detection, the nonreciprocity array with just three atomic detectors is sufficient to achieve deterministic detection (i.e., the achievable probability approaches $100%$) of a single itinerant microwave photon. Specifically, we design an array with a few current-biased Josephson junctions individually coupled to a common microwave transmission line and then discuss its feasibility.

The electromagnetic induced transparency (EIT) to atomic systems and its various applications have been extensively investigated, both theoretically and experimentally. In this paper, we study how to similarly verify these phenomena in the waveguide coupled to the transmission line resonators. By making use of real space quantum scattering theory, we calculate the transmission spectrum of the waveguide photons scattered by a single quarter-wavelength transmission line resonator. Our experimental results show that the resonant microwave transporting along the feedline is completely reflected by the resonator. This is similar to the situation of the light absorbed by the resonant atomic medium, and thus its transmission is significantly suppressed.Like the EIT phenomena in atomic gas, wherein the resonant absorption can be significantly suppressed by applying a strong pumping light to control the optical properties of medium, the transport properties of the resonant microwave can be investigated by coupling it into an auxiliary quarter-wavelength resonator in this paper. If the frequency of the auxiliary quarter-wavelength resonator is different from the resonant frequency, the calculated transmission spectrum shows that the coupling with auxiliary quarter-wavelength resonator induces the complete transmission of the resonant microwave. This is one of the features of the EIT-like effect, and can be simply explained as the frequency renormalization of the coupling resonators. Also, by adjusting the coupling strength between the resonators, the width of the microwave transmission spectrum window can be manipulated. Our experimental observations verify such an argument, but the phase shift mutation (another typical signs of the EIT effect) of the resonant microwave cannot be observed. In physics, this is because the interference between the transmitted microwave and the reflected micowave with different frequencies does not take place in the coupling region between the two resonators.It is expected that the effects with the complete EIT-like phenomena can be observed, in future, by fabricating the sample of two quarter-wavelength transmission line resonators with the same frequency, and thus the coupling between the two resonators can be controlled.

A half-wavelength cavity, wherein the electromagnetic field is quantized as standing-wave photons, is a typical artificial quantum system that has widely been used to implement quantum information processing. In this paper, we propose an approach to confirm the quantization of the electromagnetic field in another type of cavity, namely, a quarter-wavelength transmission line resonator (TLR), by using traveling-photon scattering measurements. Furthermore, we show that the number of photons in a TLR can be destructively detected by using the usual IQ-mixed technique. We hope that quarter-wavelength TLRs may also serve as quantum devices to implement on-chip solid-state quantum information processing.

针对预测控制在高超声速飞行器控制中面临的在线计算时间问题,提出了离线双模预测控制方法.首先采用LQR方法设计无约束反馈控制增益,然后根据计算得到的控制增益和高超声速飞行器的约束条件计算多面体不变集,根据多参数二次规划解的性质将多面体不变集进行区域划分并计算相应区域的自由控制变量.在线时只需要搜索当前时刻状态所处的分区,极大地减小了在线计算时间,为高超声速飞行器的实时控制提供了保证.仿真试验表明,提出的方法在保持在线算法的控制性能的同时,极大减少了仿真运行时间,实现了高超声速飞行器的实时控制.更多还原

A computationally efficient scheduled offline model predictive controller is designed for a generic hypersonic vehicle with the offline robust model predictive algorithm based on the idea of the scheduled model predictive control.Local predictive controllers are firstly designed offline around different equilibrium points, and the real-time implementation includes only the simple switching among local controllers; which avoids the on-line optimization, and the on-line computation time is reduced greatly. Through estimating the stable region of the local controllers, the stability of the scheduled controller is guaranteed. Moreover, the predictive control allows the input and the state constraints to be considered explicitly in the design phase; hence, the control performance and the constraints of the input and the states are guaranteed simultaneously. Simulation results show that the altitude and the velocity can track the reference signals in a relatively large scope with the input and the states in the given ranges. Compared with the well-known online robust model predictive control, the simulation time is greatly reduced, and the desired real-time control for the hypersonic vehicle is attainable.

Objective To study the status of smoking and air pollution in Baoji, one of the cities with high lung cancer mortality in China. Methods 964 individuals were drawn from various occupational sectors on the principle of cluster random sampling and investigated about the status of smoking. Data of air pollution was obtained from the Baoji Environmental Monitoring Station. Main indexes of air pollution were Benzo(a) pyrene [B(a)P], NOx, SO 2 and total suspended particles(TSP). Results Smoking rates were 42.1% in sample population, 60.3% in males and 6.3% in females respectively. Smoking rates in the total sample population and in females in Baoji were higher than the average level of China. The main indices of air pollution decreased dramatically since the 1980s. Now TSP level is higher than the Ambient Air Quality Standard of China slightly but SO 2 and NOx have been up to the 2nd class standard. Conclusions Air pollution of urban Baoji has been improved since 1980s, but smoking rate is still high.