文章分别采用常规环境激励法与IBIS-FS(Image by Interferometric Survey-Frequency Structures)微波干涉技术两种方法对装配整体式混凝土结构进行动力特性检测,同时按照与现浇结构混凝土相同的方法进行结构理论计算分析。结果表明:实...文章分别采用常规环境激励法与IBIS-FS(Image by Interferometric Survey-Frequency Structures)微波干涉技术两种方法对装配整体式混凝土结构进行动力特性检测,同时按照与现浇结构混凝土相同的方法进行结构理论计算分析。结果表明:实测动力特性结果与计算结果基本符合,常规环境激励法与IBIS-FS微波干涉技术可以在不需要任何激振设备的情况下检测出装配整体式混凝土结构的固有频率、振型、阻尼比;可以根据结构动力特性的测试结果对结构性能进行分析和判断。展开更多
An alternative scheme is proposed for the generation of n-qubit W states of superconducting quantum interference devices （SQUID） in cavity QED. In this scheme, Raman coupling of two lower flux states of SQUID system...An alternative scheme is proposed for the generation of n-qubit W states of superconducting quantum interference devices （SQUID） in cavity QED. In this scheme, Raman coupling of two lower flux states of SQUID system is achieved via a microwave pulse and the cavity mode. Conditioned on no photon leakage from the cavity, the n-qubit W state can be generated whether the effective coupling parameters of the SQUID to cavity mode and classical microwave fields are the same or different. Our strictly numerical simulations of the time evolution of the system including decay show that the success probability of our scheme is almost unity and the interaction time is on the order of 10-9 s. The scheme can also be used to generate the Schrodinger cat states of multi-SQUID.展开更多
In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Se...In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.展开更多
文摘文章分别采用常规环境激励法与IBIS-FS(Image by Interferometric Survey-Frequency Structures)微波干涉技术两种方法对装配整体式混凝土结构进行动力特性检测,同时按照与现浇结构混凝土相同的方法进行结构理论计算分析。结果表明:实测动力特性结果与计算结果基本符合,常规环境激励法与IBIS-FS微波干涉技术可以在不需要任何激振设备的情况下检测出装配整体式混凝土结构的固有频率、振型、阻尼比;可以根据结构动力特性的测试结果对结构性能进行分析和判断。
基金supported by National Fundamental Research Program of China under Grant No.2005CB724508National Natural Science Foundation of China under Grant Nos.10575040,10634060,60478029,and 90503010
文摘An alternative scheme is proposed for the generation of n-qubit W states of superconducting quantum interference devices （SQUID） in cavity QED. In this scheme, Raman coupling of two lower flux states of SQUID system is achieved via a microwave pulse and the cavity mode. Conditioned on no photon leakage from the cavity, the n-qubit W state can be generated whether the effective coupling parameters of the SQUID to cavity mode and classical microwave fields are the same or different. Our strictly numerical simulations of the time evolution of the system including decay show that the success probability of our scheme is almost unity and the interaction time is on the order of 10-9 s. The scheme can also be used to generate the Schrodinger cat states of multi-SQUID.
基金supported by the US National Science Foundation(Grant No.PHY-0757058)supported by the National Natural Science Foundation of China(Grant Nos.11443008 and 11503003)+2 种基金a Returned Overseas Chinese Scholars Foundation grant,and Fundamental Research Funds for the Central Universities(Grant No.2015KJJCB06)supported by the National Space Science Center,Chinese Academy of Sciences(Grant Nos.XDA04070400 and XDA04077700)Partial supports from the National Natural Science Foundation of China(Grant Nos.11305255,11171329 and 41404019)
文摘In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan,which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1–5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.
