In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean inten...In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean intensity,amplitude and visibility signals may be intrinsically biased.However,it is still unclear how large these biases are and how the data acquisition parameters influence the biases in the extracted signals.This work set out to address these questions.Analytical expressions of the biases of the extracted signals were theoretically derived by using a second-order Taylor series expansion.Extensive numerical simulations were performed to validate the theoretical results.It is illustrated that while the estimated mean intensity signal is always unbiased,the estimated amplitude and visibility signals are both positively biased.While the biases of the estimated amplitude signals are proportional to the inverse of the total number of phase steps,the biases of the estimated visibility signals are inversely proportional to the product of the total number of phase steps and the mean number of photons counted per phase step.Meanwhile,it is demonstrated that the dependence of the biases on the mean visibility is quite different from that of Talbot-Lau interferometer due to the difference in the intensity model.We expect that these results can be useful for data acquisition optimizations and interpretation of x-ray dark-field images.展开更多
A real-time data processing system is designed for the carbon dioxide dispersion interferometer(CO_(2)-DI)on EAST.The system utilizes the parallel and pipelining capabilities of an fieldprogrammable gate array(FPGA)to...A real-time data processing system is designed for the carbon dioxide dispersion interferometer(CO_(2)-DI)on EAST.The system utilizes the parallel and pipelining capabilities of an fieldprogrammable gate array(FPGA)to digitize and process the intensity of signals from the detector.Finally,the real-time electron density signals are exported through a digital-to-analog converter(DAC)module in the form of analog signals.The system has been successfully applied in the CO_(2)-DI system to provide low-latency electron density input to the plasma control system on EAST.Experimental results of the latest campaign with long-pulse discharges on EAST(2022–2023)demonstrate that the system can respond effectively in the case of rapid density changes,proving its reliability and accuracy for future electron density calculation.展开更多
A new type of polarization sensitive interferometer is proposed,named the Delta interferometer,inspired by its geometry resembling the Greek letter Delta.The main difference between the Delta interferometer and other ...A new type of polarization sensitive interferometer is proposed,named the Delta interferometer,inspired by its geometry resembling the Greek letter Delta.The main difference between the Delta interferometer and other existing interferometers,such as Michelson,Mach-Zehnder and Young's double-slit interferometers,is that the two interfering paths are asymmetrical in the Delta interferometer.The visibility of the first-order interference pattern observed in the Delta interferometer is dependent on the polarization of the incidental light.Optical coherence theory is employed to interpret this phenomenon and single-mode continuous-wave laser light is employed to verify the theoretical predictions.The theoretical and experimental results are consistent.The Delta interferometer is a perfect tool to study the reflection of electromagnetic fields in different polarizations and may find applications in polarization-sensitive scenarios.展开更多
Far-infrared(FIR)interferometer is widely used to measure the electron density in the magnetically confined fusion plasma devices.A new FIR laser interferometer with a total of 13 channels(8 horizontal channels and 5 ...Far-infrared(FIR)interferometer is widely used to measure the electron density in the magnetically confined fusion plasma devices.A new FIR laser interferometer with a total of 13 channels(8 horizontal channels and 5 oblique channels)is under development on the HL-3tokamak by using the formic-acid laser(HCOOH,f=694 GHz).In order to investigate the boundary electron density activity during the divertor discharge,three horizontal interferometry channels located at Z=-97,-76,76.5 cm have been successfully developed on HL-3 in 2023,and put into operation in recent experimental campaign,with a time resolution of<1.0μs and lineintegrated electron density resolution of~7.0×10^(16) m^(-2).This paper mainly focuses on the optical design of the three-channel interferometry system,as well as optical elements and recent experimental result on HL-3.展开更多
Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been...Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been developed to unwrap the phase difference signal in real time using FPGA, specifically designed to handle fringe jumps in the hydrogen cyanide(HCN) laser interferometer on the EAST superconducting tokamak. This method is designed for a phase demodulator using the fast Fourier transform(FFT) method at the front end. The method is better adapted for hardware implementation compared to complex mathematical analysis algorithms, such as field programmable gate array(FPGA). It has been applied to process the phase measurement results of the HCN laser interferometer on EAST in real time. Electron density results show good confidence in the fringe jump unwrapping method. Further possible application in other laser interferometers, such as the POlarimeter-INTerferometer(POINT)system on EAST tokamak is also discussed.展开更多
A dispersion interferometer(DI)has been installed and operates on the Experimental Advanced Superconducting Tokamak(EAST).This DI system utilizes a continuous-wave 9.3μm CO_(2)laser source to measure line-averaged el...A dispersion interferometer(DI)has been installed and operates on the Experimental Advanced Superconducting Tokamak(EAST).This DI system utilizes a continuous-wave 9.3μm CO_(2)laser source to measure line-averaged electron densities accurately.In contrast to conventional interferometers,the DI does not require substantial vibration isolations or compensating systems to reduce the impact of vibrations in the optical path.It also employs a ratio of modulation amplitudes,ensuring it remains immune to the variations in detected intensities.Without a variation compensation system,the DI system on EAST reaches a density resolution of less than1.8×10^(-2)πrad and a temporal resolution of 20μs.The measurements made by the POlarimeterINTerferometer(POINT)system and the far-infrared hydrogen cyanide(HCN)interferometer are remarkably consistent with the DI’s results.The possibility of fringe jumps and the impact of refraction in high-density discharge can be significantly decreased using a shorter wavelength laser source.A rapid density change of 3×10^(19)m^(-3)during 0.15 s has been measured accurately in shot No.114755 of EAST.Additionally,the DI system demonstrates dependability and stability under 305 s long-pulse discharges in shot No.122054.展开更多
Chaos is a type of motion unique to nonlinear dynamical systems,characterized by extreme sensitivity to initial conditions and the randomness,which makes it potentially useful for secure communication.Chaos research r...Chaos is a type of motion unique to nonlinear dynamical systems,characterized by extreme sensitivity to initial conditions and the randomness,which makes it potentially useful for secure communication.Chaos research require a easily controllable chaotic oscillator.Chaotic behavior in optical bistability provides a simple theoretical model.Based on the theoretical model,a novel chaotic oscillator in frequency domain is proposed.The chaotic oscillator is composed of a tunable fiber laser,fiber Fabry⁃Perot interferometer(FFPI)and hybrid delayed feedback loop.The laser itself plays a part in delay time which is induced by PZT device.The chaotic oscillator is realized by experiments and chaos behaviors are observed.The chaos oscillator has the characteristic of simplicity and flexibility.It have potential application value in the field of fiber optical communication encryption.展开更多
The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- sc...The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- scope system. The driven equation shows the thermally driven gyroscope can work for a long time but the pres- sure driven one cannot. From the current equation, the superfluid currents passing through the weak link contain the AC currents which show the rotation flux, and other currents caused by drive. As shown in the position equa- tion, the displacement of diaphragm is the only detectable parameter in the gyroscope system. The model is tested by the simulations based on experimental parameters, and can be used to research performance of the gyroscope and analyse the gyroscope error.展开更多
A distinct method to show a quantum object behaving both as wave and as particle is proposed and described in some detail. We make a systematic analysis using the elementary methodology of quantum mechanics upon Young...A distinct method to show a quantum object behaving both as wave and as particle is proposed and described in some detail. We make a systematic analysis using the elementary methodology of quantum mechanics upon Young＇s two-slit interferometer and the Mach-Zehnder two-arm interferometer with the focus placed on how to measure the interference pattern （wave nature） and the which-way information （particle nature） of quantum objects. We design several schemes to simultaneously acquire the which-way information for an individual quantum object and the high-contrast interference pattern for an ensemble of these quantum objects by placing two sets of measurement instruments that are well separated in space and whose perturbation of each other is negligibly small within the interferometer at the same time. Yet, improper arrangement and cooperation of these two sets of measurement instruments in the interferometer would lead to failure of simultaneous observation of wave and particle behaviors. The internal freedoms of quantum objects could be harnessed to probe both the which-way information and the interference pattern for the center-of-mass motion. That quantum objects can behave beyond the wave-particle duality and the complementarity principle would stimulate new conceptual examination and exploration of quantum theory at a deeper level.展开更多
X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of sample...X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.展开更多
An ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer （FPI） is proposed and employed for ultra- sonic imaging of seismic physical models （SPMs）. The FPI comprises a flexible ultra-thin gold fil...An ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer （FPI） is proposed and employed for ultra- sonic imaging of seismic physical models （SPMs）. The FPI comprises a flexible ultra-thin gold film and the end face of a graded-index multimode fiber （MMF）, both of which are enclosed in a ceramic tube. The MMF in a specified length can collimate the diverged light beam and compensate for the light loss inside the air cavity, leading to an increased spectral fringe visibility and thus a steeper spectral slope. By using the spectral sideband filtering technique, the collimated FP1 shows an improved ultrasonic response. Moreover, two-dimensional images of two SPMs are achieved in air by recon- structing the pulse-echo signals through using the time-of-flight approach. The proposed sensor with easy fabrication and compact size can be a good candidate for high-sensitivity and high-precision nondestructive testing of SPMs.展开更多
A new multi-channel far infrared （FIR） laser interferometer was built up and ap- plied to HL-2A. The unique feature of real-time heterodyne interferometer is the combination of high power radiation source （300 mW）...A new multi-channel far infrared （FIR） laser interferometer was built up and ap- plied to HL-2A. The unique feature of real-time heterodyne interferometer is the combination of high power radiation source （300 mW）, lower noise room temperature detector （noise tempera- ture below 6000 K） with good spatial resolution of 7 cm. Various parameters are optimized for maximum laser output power. Zero crossings of the signals are counted with field programmable gate array （FPGA） digital circuitry yielding the resolution of 1/1000 fringe. The newly measured results including density fluctuation are also presented.展开更多
This work presents an optical method using the Mach–Zehnder interferometer. We especially diagnose a pure nitrogen gas subjected to a point to plane corona discharge, and visualize the density spatial map. The intere...This work presents an optical method using the Mach–Zehnder interferometer. We especially diagnose a pure nitrogen gas subjected to a point to plane corona discharge, and visualize the density spatial map. The interelectrode distance equals6 mm and the variation of the optical path has been measured at different pressures： 220 Torr, 400 Torr, and 760 Torr.The interferograms are recorded with a CCD camera, and the numerical analysis of these interferograms is assured by the inverse Abel transformation. The nitrogen density is extracted through the Gladstone–Dale relation. The obtained results are in close agreement with values available in the literature.展开更多
A novel fiber optic moiréinterferometer has been developed and demonstrated.A He-Ne laser and three high birefringence fibers were used to configurate a fiber optic interferometer.The moiréfringe patterns fo...A novel fiber optic moiréinterferometer has been developed and demonstrated.A He-Ne laser and three high birefringence fibers were used to configurate a fiber optic interferometer.The moiréfringe patterns formed by the interferometer depend on the arrangement of three fiber ends.The experiment results and the intensity distribution function of the interference patterns are given.展开更多
By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the con...By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the continuous-wave and pulse pumped four-wave mixing experiments to verify the dependence of conversion efficiency on the coupling conditions of the four interacting beams, respectively. Under the continuous-wave pump, the four-wave mixing efficiency gets maximized when both the pump and signal/idler beams are closely operated at the critical coupling point, while for the pulse pump case, the efficiency can be enhanced greatly when the pump and converted idler beams are all overcoupled. These experiment results agree well with our theoretical calculations. Our design provides a platform for explicitly characterizing the four-wave mixing under different pumping conditions, and offers a method to optimize the four-wave mixing, which will facilitate the development of on-chip all-optical signal processing with a higher efficiency or reduced pump power.展开更多
A high-sensitivity curvature sensor based on an up-taper-core-offset structure is proposed and demonstrated in this paper. Here two specially designed cascaded up-tapers with maximum diameters of 247 μm and 251 μm, ...A high-sensitivity curvature sensor based on an up-taper-core-offset structure is proposed and demonstrated in this paper. Here two specially designed cascaded up-tapers with maximum diameters of 247 μm and 251 μm, respectively, are used as a cladding mode exciting component. The excited cladding modes will propagate in the cladding and re-couplers with the core mode at the core-offset jointing point. When the curvature is changed, the dip wavelength of the sensor will shift to a blue wavelength and an average curvature sensitivity of more than -12.5 nm/m^-1 is achieved within the measured curvature intervals.展开更多
We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interfero...We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interferometers, the FSM will degrade the sensitivity while the FLM does not. The sensitivity-improvement factor of the FLM over the FSM depends on the type of noises, which is validated by numerical simulations. The detailed quantitative analysis on this fundamental issue is presented, and our analysis is readily extendable to other kinds of noises as well as other fringe shapes in addition to a cosine one.展开更多
By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak wh...By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak which is in-dependent of the other factors when the topological superconductor is grounded. Especially, an additional phase appears when the topological superconductor is in the strong Coulomb regime, which induces a new conductance resonant peak compared with the structure of replacing the topological superconductor by a quantum dot, and the conductance oscillation with the magnetic flux reveals a 2π phase shift by raising （lowering） a charge on the capacitor.展开更多
We theoretically investigate the wave–particle duality based on a Raman atom interferometer, via the interaction between the atom and Raman laser, which is similar to the optical Mach–Zehnder interferometer. The wav...We theoretically investigate the wave–particle duality based on a Raman atom interferometer, via the interaction between the atom and Raman laser, which is similar to the optical Mach–Zehnder interferometer. The wave and which-way information are stored in the atomic internal states. For the φ- π- π /2 type of atom interferometer, we find that the visibility(V) and predictability(P) still satisfy the duality relation, P2+ V2≤ 1.展开更多
We study a scheme for Mach-Zehnder （MZ） interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer. Two-mode squeezed states can be changed into two types ...We study a scheme for Mach-Zehnder （MZ） interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer. Two-mode squeezed states can be changed into two types of in- puts for MZ interferometer： two squeezed states and Einstein-Podolsky-Rosen （EPR） entangled states. The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned, and are measured by the balanced homodyne detection system. Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields. Since MZ interferometer can be used to realize some quantum operations, this work will have the important applications in quantum information and metrology.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1532113,11475170,11905041)Anhui Provincial Natural Science Foundation(Grant No.2208085MA18)Fundamental Research Funds for the Central Universities(Grant No.JZ2022HGTB0244)。
文摘In x-ray dark-field imaging using dual phase grating interferometer,multi-contrast signals are extracted from a set of acquired phase-stepping data by using the least-squares fitting algorithm.The extracted mean intensity,amplitude and visibility signals may be intrinsically biased.However,it is still unclear how large these biases are and how the data acquisition parameters influence the biases in the extracted signals.This work set out to address these questions.Analytical expressions of the biases of the extracted signals were theoretically derived by using a second-order Taylor series expansion.Extensive numerical simulations were performed to validate the theoretical results.It is illustrated that while the estimated mean intensity signal is always unbiased,the estimated amplitude and visibility signals are both positively biased.While the biases of the estimated amplitude signals are proportional to the inverse of the total number of phase steps,the biases of the estimated visibility signals are inversely proportional to the product of the total number of phase steps and the mean number of photons counted per phase step.Meanwhile,it is demonstrated that the dependence of the biases on the mean visibility is quite different from that of Talbot-Lau interferometer due to the difference in the intensity model.We expect that these results can be useful for data acquisition optimizations and interpretation of x-ray dark-field images.
基金funded and supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)the HFIPS Director’s Fund(No.YZJJKX202301)+1 种基金the Anhui Provincial Major Science and Technology Project(No.2023z020004)Task JB22001 from the Anhui Provincial Department of Economic and Information Technology。
文摘A real-time data processing system is designed for the carbon dioxide dispersion interferometer(CO_(2)-DI)on EAST.The system utilizes the parallel and pipelining capabilities of an fieldprogrammable gate array(FPGA)to digitize and process the intensity of signals from the detector.Finally,the real-time electron density signals are exported through a digital-to-analog converter(DAC)module in the form of analog signals.The system has been successfully applied in the CO_(2)-DI system to provide low-latency electron density input to the plasma control system on EAST.Experimental results of the latest campaign with long-pulse discharges on EAST(2022–2023)demonstrate that the system can respond effectively in the case of rapid density changes,proving its reliability and accuracy for future electron density calculation.
基金Project supported by the Shanxi Key Research and Development Project(Grant No.2019ZDLGY09-08)Shanxi Nature and Science Basic Research Project(Grant No.2019JLP-18).
文摘A new type of polarization sensitive interferometer is proposed,named the Delta interferometer,inspired by its geometry resembling the Greek letter Delta.The main difference between the Delta interferometer and other existing interferometers,such as Michelson,Mach-Zehnder and Young's double-slit interferometers,is that the two interfering paths are asymmetrical in the Delta interferometer.The visibility of the first-order interference pattern observed in the Delta interferometer is dependent on the polarization of the incidental light.Optical coherence theory is employed to interpret this phenomenon and single-mode continuous-wave laser light is employed to verify the theoretical predictions.The theoretical and experimental results are consistent.The Delta interferometer is a perfect tool to study the reflection of electromagnetic fields in different polarizations and may find applications in polarization-sensitive scenarios.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2019YFE03020004,2018YFE0304102 and 2019YFE03020002)the Department of Science and Technology of Sichuan Province(No.2020YJ0463)。
文摘Far-infrared(FIR)interferometer is widely used to measure the electron density in the magnetically confined fusion plasma devices.A new FIR laser interferometer with a total of 13 channels(8 horizontal channels and 5 oblique channels)is under development on the HL-3tokamak by using the formic-acid laser(HCOOH,f=694 GHz).In order to investigate the boundary electron density activity during the divertor discharge,three horizontal interferometry channels located at Z=-97,-76,76.5 cm have been successfully developed on HL-3 in 2023,and put into operation in recent experimental campaign,with a time resolution of<1.0μs and lineintegrated electron density resolution of~7.0×10^(16) m^(-2).This paper mainly focuses on the optical design of the three-channel interferometry system,as well as optical elements and recent experimental result on HL-3.
基金funded and supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-73-01-001228)the HFIPS Director’s Fund(No.YZJJKX202301)+1 种基金Anhui Provincial Major Science and Technology Project(No.2023z020004)Task JB22001 from the Anhui Provincial Department of Economic and Information Technology。
文摘Electron density in fusion plasma is usually diagnosed using laser-aided interferometers. The phase difference signal obtained after phase demodulation is wrapped, which is also called a fringe jump. A method has been developed to unwrap the phase difference signal in real time using FPGA, specifically designed to handle fringe jumps in the hydrogen cyanide(HCN) laser interferometer on the EAST superconducting tokamak. This method is designed for a phase demodulator using the fast Fourier transform(FFT) method at the front end. The method is better adapted for hardware implementation compared to complex mathematical analysis algorithms, such as field programmable gate array(FPGA). It has been applied to process the phase measurement results of the HCN laser interferometer on EAST in real time. Electron density results show good confidence in the fringe jump unwrapping method. Further possible application in other laser interferometers, such as the POlarimeter-INTerferometer(POINT)system on EAST tokamak is also discussed.
基金supported by the Comprehensive Research Facility for Fusion Technology Program of China(No.2018-000052-7301-001228)the Major Special Science and Technology Project of Anhui Province(No.912188707023)。
文摘A dispersion interferometer(DI)has been installed and operates on the Experimental Advanced Superconducting Tokamak(EAST).This DI system utilizes a continuous-wave 9.3μm CO_(2)laser source to measure line-averaged electron densities accurately.In contrast to conventional interferometers,the DI does not require substantial vibration isolations or compensating systems to reduce the impact of vibrations in the optical path.It also employs a ratio of modulation amplitudes,ensuring it remains immune to the variations in detected intensities.Without a variation compensation system,the DI system on EAST reaches a density resolution of less than1.8×10^(-2)πrad and a temporal resolution of 20μs.The measurements made by the POlarimeterINTerferometer(POINT)system and the far-infrared hydrogen cyanide(HCN)interferometer are remarkably consistent with the DI’s results.The possibility of fringe jumps and the impact of refraction in high-density discharge can be significantly decreased using a shorter wavelength laser source.A rapid density change of 3×10^(19)m^(-3)during 0.15 s has been measured accurately in shot No.114755 of EAST.Additionally,the DI system demonstrates dependability and stability under 305 s long-pulse discharges in shot No.122054.
文摘Chaos is a type of motion unique to nonlinear dynamical systems,characterized by extreme sensitivity to initial conditions and the randomness,which makes it potentially useful for secure communication.Chaos research require a easily controllable chaotic oscillator.Chaotic behavior in optical bistability provides a simple theoretical model.Based on the theoretical model,a novel chaotic oscillator in frequency domain is proposed.The chaotic oscillator is composed of a tunable fiber laser,fiber Fabry⁃Perot interferometer(FFPI)and hybrid delayed feedback loop.The laser itself plays a part in delay time which is induced by PZT device.The chaotic oscillator is realized by experiments and chaos behaviors are observed.The chaos oscillator has the characteristic of simplicity and flexibility.It have potential application value in the field of fiber optical communication encryption.
基金Supported by the National Natural Science Foundation of China(61074162)the Ph.D.Program Foundation of Ministry of Education of China(200802870011)~~
文摘The mathematical model of 4He quantum interferometer gyroscope is presented. The model includes the driven equation, the current equation and the position equation. Therefore, it can sufficiently describe the gyro- scope system. The driven equation shows the thermally driven gyroscope can work for a long time but the pres- sure driven one cannot. From the current equation, the superfluid currents passing through the weak link contain the AC currents which show the rotation flux, and other currents caused by drive. As shown in the position equa- tion, the displacement of diaphragm is the only detectable parameter in the gyroscope system. The model is tested by the simulations based on experimental parameters, and can be used to research performance of the gyroscope and analyse the gyroscope error.
基金supported by the National Natural Science Foundation of Chinathe Ministry of Science and Technology of ChinaChinese Academy of Sciences
文摘A distinct method to show a quantum object behaving both as wave and as particle is proposed and described in some detail. We make a systematic analysis using the elementary methodology of quantum mechanics upon Young＇s two-slit interferometer and the Mach-Zehnder two-arm interferometer with the focus placed on how to measure the interference pattern （wave nature） and the which-way information （particle nature） of quantum objects. We design several schemes to simultaneously acquire the which-way information for an individual quantum object and the high-contrast interference pattern for an ensemble of these quantum objects by placing two sets of measurement instruments that are well separated in space and whose perturbation of each other is negligibly small within the interferometer at the same time. Yet, improper arrangement and cooperation of these two sets of measurement instruments in the interferometer would lead to failure of simultaneous observation of wave and particle behaviors. The internal freedoms of quantum objects could be harnessed to probe both the which-way information and the interference pattern for the center-of-mass motion. That quantum objects can behave beyond the wave-particle duality and the complementarity principle would stimulate new conceptual examination and exploration of quantum theory at a deeper level.
基金Project supported by the Major State Basic Research Development Program of China(Grant No.2012CB825800)the Science Fund for Creative Research Groups,China(Grant No.11321503)+1 种基金the National Natural Science Foundation of China(Grant Nos.11179004,10979055,11205189,and 11205157)the Japan–Asia Youth Exchange Program in Science(SAKURA Exchange Program in Science)Administered by the Japan Science and Technology Agency
文摘X-ray Talbot-Lau interferometer has been used most widely to perform x-ray phase-contrast imaging with a con- ventional low-brilliance x-ray source, and it yields high-sensitivity phase and dark-field images of samples producing low absorption contrast, thus beating tremendous potential for future clinical diagnosis. In this work, by changing the accel- erating voltage of the x-ray tube from 35 kV to 45 kV, x-ray phase-contrast imaging of a test sample is performed at each integer value of the accelerating voltage to investigate the characteristic of an x-ray Talbot-Lau interferometer （located in the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan） versus tube voltage. Ex- perimental results and data analysis show that within a range this x-ray Talbot-Lau interferometer is not sensitive to the accelerating voltage of the tube with a constant fringe visibility of ~ 44%. This x-ray Talbot-Lau interferometer research demonstrates the feasibility of a new dual energy phase-contrast x-ray imaging strategy and the possibility to collect a refraction spectrum.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61735014,61327012,and 61275088)the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.08JZ58)the Northwest University Graduate Innovation and Creativity Funds,China(Grant No.YZZ17088)
文摘An ultrasonic sensitivity-improved fiber-optic Fabry-Perot interferometer （FPI） is proposed and employed for ultra- sonic imaging of seismic physical models （SPMs）. The FPI comprises a flexible ultra-thin gold film and the end face of a graded-index multimode fiber （MMF）, both of which are enclosed in a ceramic tube. The MMF in a specified length can collimate the diverged light beam and compensate for the light loss inside the air cavity, leading to an increased spectral fringe visibility and thus a steeper spectral slope. By using the spectral sideband filtering technique, the collimated FP1 shows an improved ultrasonic response. Moreover, two-dimensional images of two SPMs are achieved in air by recon- structing the pulse-echo signals through using the time-of-flight approach. The proposed sensor with easy fabrication and compact size can be a good candidate for high-sensitivity and high-precision nondestructive testing of SPMs.
基金National Natural Science Foundation of China (Nos.10575030,10675043)the JSPS-CAS Core University Program in the field of Plasma and Nuclear Fusion
文摘A new multi-channel far infrared （FIR） laser interferometer was built up and ap- plied to HL-2A. The unique feature of real-time heterodyne interferometer is the combination of high power radiation source （300 mW）, lower noise room temperature detector （noise tempera- ture below 6000 K） with good spatial resolution of 7 cm. Various parameters are optimized for maximum laser output power. Zero crossings of the signals are counted with field programmable gate array （FPGA） digital circuitry yielding the resolution of 1/1000 fringe. The newly measured results including density fluctuation are also presented.
文摘This work presents an optical method using the Mach–Zehnder interferometer. We especially diagnose a pure nitrogen gas subjected to a point to plane corona discharge, and visualize the density spatial map. The interelectrode distance equals6 mm and the variation of the optical path has been measured at different pressures： 220 Torr, 400 Torr, and 760 Torr.The interferograms are recorded with a CCD camera, and the numerical analysis of these interferograms is assured by the inverse Abel transformation. The nitrogen density is extracted through the Gladstone–Dale relation. The obtained results are in close agreement with values available in the literature.
文摘A novel fiber optic moiréinterferometer has been developed and demonstrated.A He-Ne laser and three high birefringence fibers were used to configurate a fiber optic interferometer.The moiréfringe patterns formed by the interferometer depend on the arrangement of three fiber ends.The experiment results and the intensity distribution function of the interference patterns are given.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.61632021,11627810,11690031,and 11621091)Open Funds from the State Key Laboratory of High Performance Computing of China(HPCL,National University of Defense Technology)
文摘By designing and fabricating a series of dual-interferometer coupled silicon microrings, the coupling condition of the pump, signal, and idler beams can be engineered independently and then we carried out both the continuous-wave and pulse pumped four-wave mixing experiments to verify the dependence of conversion efficiency on the coupling conditions of the four interacting beams, respectively. Under the continuous-wave pump, the four-wave mixing efficiency gets maximized when both the pump and signal/idler beams are closely operated at the critical coupling point, while for the pulse pump case, the efficiency can be enhanced greatly when the pump and converted idler beams are all overcoupled. These experiment results agree well with our theoretical calculations. Our design provides a platform for explicitly characterizing the four-wave mixing under different pumping conditions, and offers a method to optimize the four-wave mixing, which will facilitate the development of on-chip all-optical signal processing with a higher efficiency or reduced pump power.
文摘A high-sensitivity curvature sensor based on an up-taper-core-offset structure is proposed and demonstrated in this paper. Here two specially designed cascaded up-tapers with maximum diameters of 247 μm and 251 μm, respectively, are used as a cladding mode exciting component. The excited cladding modes will propagate in the cladding and re-couplers with the core mode at the core-offset jointing point. When the curvature is changed, the dip wavelength of the sensor will shift to a blue wavelength and an average curvature sensitivity of more than -12.5 nm/m^-1 is achieved within the measured curvature intervals.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41127002,11574099,41504034,and 11474115)the National Basic Research Program of China(Grant No.2010CB832806)
文摘We investigated the sensitivities of atom interferometers in the usual fringe-scanning method （FSM） versus the fringe- locking method （FLM）. The theoretical analysis shows that for typical noises in atom interferometers, the FSM will degrade the sensitivity while the FLM does not. The sensitivity-improvement factor of the FLM over the FSM depends on the type of noises, which is validated by numerical simulations. The detailed quantitative analysis on this fundamental issue is presented, and our analysis is readily extendable to other kinds of noises as well as other fringe shapes in addition to a cosine one.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB922103)
文摘By using the non-equilibrium Green＇s function technique, we investigate the electronic transport properties in an Aharonov-Bohm interferometer coupling with Majorana fermions. We find a fixed unit conductance peak which is in-dependent of the other factors when the topological superconductor is grounded. Especially, an additional phase appears when the topological superconductor is in the strong Coulomb regime, which induces a new conductance resonant peak compared with the structure of replacing the topological superconductor by a quantum dot, and the conductance oscillation with the magnetic flux reveals a 2π phase shift by raising （lowering） a charge on the capacitor.
基金supported by the National Natural Science Foundation of China(Grant No.51275523)the Special Research Fund for the Doctoral Program of Higher Education,China(Grant No.20134307110009)
文摘We theoretically investigate the wave–particle duality based on a Raman atom interferometer, via the interaction between the atom and Raman laser, which is similar to the optical Mach–Zehnder interferometer. The wave and which-way information are stored in the atomic internal states. For the φ- π- π /2 type of atom interferometer, we find that the visibility(V) and predictability(P) still satisfy the duality relation, P2+ V2≤ 1.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921601)the National Natural Science Foundation of China(Grant Nos.11234008,11361161002,and 61571276)the Natural Science Foundation of Shanxi Province,China(Grant No.2015011007)
文摘We study a scheme for Mach-Zehnder （MZ） interferometer as a quantum linear device by injecting two-mode squeezed input states into two ports of interferometer. Two-mode squeezed states can be changed into two types of in- puts for MZ interferometer： two squeezed states and Einstein-Podolsky-Rosen （EPR） entangled states. The interference patterns of the MZ interferometer vary periodically as the relative phase of the two arms of the interferometer is scanned, and are measured by the balanced homodyne detection system. Our experiments show that there are different interference patterns and periodicity of the output quantum states for two cases which depend on the relative phase of input optical fields. Since MZ interferometer can be used to realize some quantum operations, this work will have the important applications in quantum information and metrology.
