Detecting magnetic field is of great importance for many applications,such as magnetoencephalography and underground prospecting.There have been many magnetometers being widely used since the age of Hall magnetometer....Detecting magnetic field is of great importance for many applications,such as magnetoencephalography and underground prospecting.There have been many magnetometers being widely used since the age of Hall magnetometer.One of the magnetometers,the superconducting quantum interference device,is capable of measuring femtotesla magnetic fields at cryogenic temperature.However,a solid-state magnetometer with femtotesla sensitivity under ambient conditions remains elusive.Here we present a hybrid magnetometer based on the ensemble nitrogen-vacancy centers in diamond with the sensitivity of(195±60)fT/Hz^(1/2)under ambient conditions,which can be further advanced to 11 fT/Hz^(1/2)at 100 Hz with cutting-edge fabrication technologies.Our method will find potential applications in biomagnetism and geomagnetism.展开更多
By using our computational fluid dynamic models, a new type of single engine capable of operating over a wide range of Mach numbers from subsonic to hypersonic regimes is proposed for airplanes, whereas traditional pi...By using our computational fluid dynamic models, a new type of single engine capable of operating over a wide range of Mach numbers from subsonic to hypersonic regimes is proposed for airplanes, whereas traditional piston engines, turbojet engines, and scram engines work only under a narrower range of operating conditions. The new engine has no compressors or turbines such as those used in conventional turbojet engines. An important point is its system of super multijets that collide to compress gas for the transonic regime. Computational fluid dynamics is applied to clarify the potential of this engine. The peak pressure at the combustion center is over 2.5 MPa, while that just before ignition is over 1.0 MPa. The maximum power of this engine will be sufficient for actual use. Under the conditions of higher Mach numbers, the main intake passage located in front of the super multijet nozzles, takes in air more. That results in a ram or scramjet engine for supersonic and hypersonic conditions.展开更多
We have set up a novel system for shaping the Gaussian laser beams into super-Gaussian beams.The digital micro-mirror device(DMD)is able to modulate the laser light spatially through binary-amplitude modulation mechan...We have set up a novel system for shaping the Gaussian laser beams into super-Gaussian beams.The digital micro-mirror device(DMD)is able to modulate the laser light spatially through binary-amplitude modulation mechanism.With DMD,the irradiance of the laser beam can be redistributed flexibly and various beams with different intensity distribution can be produced.A super-Gaussian beam has been successfully shaped from the Gaussian beam with the use of DMD.This technique will be widely applied in lithography,quantum emulation and holographic optical tweezers which require precise control of beam profile.展开更多
基金supported by the National Key R&D Program of China(2018YFA0306600 and 2016YFB0501603)the National Natural Science Foundation of China(11761131011)+2 种基金the Chinese Academy of Sciences(GJJSTD20170001,QYZDY-SSW-SLH004 and QYZDBSSW-SLH005)Anhui Initiative in Quantum Information Technologies(AHY050000)the Youth Innovation Promotion Association of Chinese Academy of Sciences for the support。
文摘Detecting magnetic field is of great importance for many applications,such as magnetoencephalography and underground prospecting.There have been many magnetometers being widely used since the age of Hall magnetometer.One of the magnetometers,the superconducting quantum interference device,is capable of measuring femtotesla magnetic fields at cryogenic temperature.However,a solid-state magnetometer with femtotesla sensitivity under ambient conditions remains elusive.Here we present a hybrid magnetometer based on the ensemble nitrogen-vacancy centers in diamond with the sensitivity of(195±60)fT/Hz^(1/2)under ambient conditions,which can be further advanced to 11 fT/Hz^(1/2)at 100 Hz with cutting-edge fabrication technologies.Our method will find potential applications in biomagnetism and geomagnetism.
文摘By using our computational fluid dynamic models, a new type of single engine capable of operating over a wide range of Mach numbers from subsonic to hypersonic regimes is proposed for airplanes, whereas traditional piston engines, turbojet engines, and scram engines work only under a narrower range of operating conditions. The new engine has no compressors or turbines such as those used in conventional turbojet engines. An important point is its system of super multijets that collide to compress gas for the transonic regime. Computational fluid dynamics is applied to clarify the potential of this engine. The peak pressure at the combustion center is over 2.5 MPa, while that just before ignition is over 1.0 MPa. The maximum power of this engine will be sufficient for actual use. Under the conditions of higher Mach numbers, the main intake passage located in front of the super multijet nozzles, takes in air more. That results in a ram or scramjet engine for supersonic and hypersonic conditions.
基金supported by the National Natural Science Foundation of China(Grant No.60974038)the Project of Provincial Teaching Research in Anhui Institutions of Higher Education(Grant No.2012jyxm006)
文摘We have set up a novel system for shaping the Gaussian laser beams into super-Gaussian beams.The digital micro-mirror device(DMD)is able to modulate the laser light spatially through binary-amplitude modulation mechanism.With DMD,the irradiance of the laser beam can be redistributed flexibly and various beams with different intensity distribution can be produced.A super-Gaussian beam has been successfully shaped from the Gaussian beam with the use of DMD.This technique will be widely applied in lithography,quantum emulation and holographic optical tweezers which require precise control of beam profile.
