Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with recons...Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.展开更多
A scheme for approximately and conditionally teleporting an unknown atomic state via two-photon interaction in cavity QED is proposed. It is the extension of the scheme of Ref. [11] [Phys. Rev. A 69 (2004) 064302], ...A scheme for approximately and conditionally teleporting an unknown atomic state via two-photon interaction in cavity QED is proposed. It is the extension of the scheme of Ref. [11] [Phys. Rev. A 69 (2004) 064302], which is based on Jaynes-Cummings model in QED and where only a time point of system evolution and the corresponding fidelity implementing the teleportation are given. In our scheme, the two-photon interaction Jaynes-Cummings model is used to realize the approximate and conditional teleportation. Our scheme does not involve the Bell-state measurement and an additional atom, only requiring two atoms and one single-mode cavity. The fidelity of the scheme is higher than that of Ref. [11]. The scheme may be generalized to not only the teleportation of the state of a cavity mode to another mode by means of a single atom but also the teleportation of the state of a trapped ion.展开更多
In a previous work [Commun. Theor. Phys. 45 (2006) 79] a scheme was presented for approximate and conditional teleportation of an unknown atomic state in a QED-cavity without Bell-state measurement via two-photon Ja...In a previous work [Commun. Theor. Phys. 45 (2006) 79] a scheme was presented for approximate and conditional teleportation of an unknown atomic state in a QED-cavity without Bell-state measurement via two-photon Jaynes-Cummings model in the effective Hamiltonian approach. This comment presents an alternative method, based on the so called "full two-photon Jaynes-Cummings Hamiltonian approach". Accordingly, it describes the evolution of the two-photon degenerate process for arbitrary average photon number inside the cavity, as the correct way to implement teleportation in this scenario.展开更多
We present a scheme in which the N-atom W state is teleported by employing the selective interactionof a cavity field with a driven three-level atom in the A configuration and detecting a single atom in one of the gro...We present a scheme in which the N-atom W state is teleported by employing the selective interactionof a cavity field with a driven three-level atom in the A configuration and detecting a single atom in one of the groundstates.The long-lived W state is teleported from atom A to atom B when the atoms B and A are sent through acavity successively and atom A is then detected.The advantage is that the present one does not involve the Bell-statemeasurement and is robust against the atomic spontaneous emission.展开更多
An experimentally feasible scheme for teleportation of an unknown two-atom entangled state is proposed. Our scheme uses a duster state as the quantum channel, where we do not need any joint Bell-state measurement. Mor...An experimentally feasible scheme for teleportation of an unknown two-atom entangled state is proposed. Our scheme uses a duster state as the quantum channel, where we do not need any joint Bell-state measurement. Moreover the successful probability and fidelity of teleportation can both reach 1.0. The current scheme can be realized within the current experimental technology.展开更多
This paper proposes a scheme for information concentration of two remote two-level atoms in cavity QED. This scheme does not involve the Bell-state measurement. During the interaction between atom and cavity, the cavi...This paper proposes a scheme for information concentration of two remote two-level atoms in cavity QED. This scheme does not involve the Bell-state measurement. During the interaction between atom and cavity, the cavity frequency is large-detuned from the atomic transition frequency, thus the scheme is insensitive to both the cavity decay and the thermal field. This idea can directly be generalized in the case of multi-atom information concentration.展开更多
An alternative scheme is proposed for teleportation of an unknown atomic-entangled state. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the...An alternative scheme is proposed for teleportation of an unknown atomic-entangled state. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the previously proposed scheme of [Commun. Theor. Phys. 47 (2007) 253], the present scheme is ascendant, since the fidelity is 1.0 in principle similarly without the Bell-state measurement. The scheme may be generalized to not only the teleportation of the cavity-mode-entangled-state but also the teleportation of the multi-atomic entangled states included in generalized GHZ states. And the scheme is experimentally feasible based on the current cavity QED technique.展开更多
A scheme for approximately and conditionally teleporting an unknown atomic-entangled state in cavity QED is proposed. It is the novel extension of the scheme of [Phys. Rev. A 69 (200,I) 06,1302], where the state to ...A scheme for approximately and conditionally teleporting an unknown atomic-entangled state in cavity QED is proposed. It is the novel extension of the scheme of [Phys. Rev. A 69 (200,I) 06,1302], where the state to be teleported is an unknown atomic state and where only a time point of system evolution and the corresponding: fidelity implementing the telèportation are given. In fact, there exists multi-time points and the corresponding fidelities, which are Shown in this paper and then are used to realize the approximate and conditional teleportation of the unknown atomic-entangled state. Naturally, our scheme does not involve the Bell-state measurement or an additional atom, which is required in the Bell-state measurement, only requiring one single-mode cavity. The scheme may be generalized to not only the teleportation of the cavity-mode-entangled-state by means of a single atom but also the teleportation of the unknown trapped-ion-entangled-state in a linear ion trap and the teleportation of the multi-atomic entangled states included in generalized GHZ states.展开更多
We propose a protocol to implement the nonlocal Bell-state measurement, which is nearly determinate with the help of weak cross-Kerr nonlinearities and quantum non-destructive photon number resolving detection. Based ...We propose a protocol to implement the nonlocal Bell-state measurement, which is nearly determinate with the help of weak cross-Kerr nonlinearities and quantum non-destructive photon number resolving detection. Based on the nonlocal Bell-state measurement, we implement the quantum information transfer from one place to another. The process is different from conventional teleportation but can be regarded as a novel form of teleportation without entangled channel and classic communication.展开更多
We propose a scheme for sharing an arbitrary unknown two-qubit state among three parties by using afour-qubit cluster-class state and a Bell state as a quantum channel With a quantum controlled phase gate (QCPG)operat...We propose a scheme for sharing an arbitrary unknown two-qubit state among three parties by using afour-qubit cluster-class state and a Bell state as a quantum channel With a quantum controlled phase gate (QCPG)operation and a local unitary operation,any one of the two agents has the access to reconstruct the original state ifhe/she collaborates with the other one,whilst individual agent obtains no information.As all quantum resource canbe used to carry the useful information,the intrinsic efficiency of qubits approaches the maximal value.Moreover,thepresent scheme is more feasible with present-day technique.展开更多
Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orien...Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orientations, etc. of the three array arrangements, i. e., linear array, T-type array and pentagon array, on the resolution of the directional spreading of waves, are investigated experimentally. This study can be used as a reference in the experimental study and the field measurement of directional waves.展开更多
An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence(LIF)methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar ...An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence(LIF)methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar flame. In our approach, particular attention is paid to the linear laser-induced fluorescence and absorption processes, and experimental details as well. Through measuring the temperature, LIF signal distribution and integrated absorption, spatially absolute OH concentrations profiles are successfully resolved. These experimental results are then compared with the numerical simulation. It is proved that the good quality of the results implies that this method is suitable for calibrating the OH-PLIF measurement in a practical combustor.展开更多
The one-step quantum secure direct communication(QSDC)(Sci.Bull.67,367(2022))can effectively simplify QSDC’s operation and reduce message loss.For enhancing its security under practical experimental condition,we prop...The one-step quantum secure direct communication(QSDC)(Sci.Bull.67,367(2022))can effectively simplify QSDC’s operation and reduce message loss.For enhancing its security under practical experimental condition,we propose two measurement-device-independent(MDI)one-step QSDC protocols,which can resist all possible attacks from imperfect measurement devices.In both protocols,the communication parties prepare identical polarization-spatial-mode two-photon hyperentangled states and construct the hyperentanglement channel by hyperentanglement swapping.The first MDI one-step QSDC protocol adopts the nonlinear-optical complete hyperentanglement Bell state measurement(HBSM)to construct the hyperentanglement channel,while the second protocol adopts the linear-optical partial HBSM.Then,the parties encode the photons in the polarization degree of freedom and send them to the third party for the hyperentanglementassisted complete polarization Bell state measurement.Both protocols are unconditionally secure in theory.The simulation results show the MDI one-step QSDC protocol with complete HBSM attains the maximal communication distance of about354 km.Our MDI one-step QSDC protocols may have potential applications in the future quantum secure communication field.展开更多
Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the...Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the influences of atmospheric conditions,settled height,view angle of infrared thermography,and investigating time of temperature measuring on the performance of the CWSI.Three irrigation treatments were used to create different soil water conditions during the 2020-2021 and 2021-2022 winter wheat-growing seasons.The CWSI was calculated using the CWSI-E(an empirical approach)and CWSI-T(a theoretical approach)based on the T_(c).Weather conditions were recorded continuously throughout the experimental period.The results showed that atmospheric conditions influenced the estimation of the CWSI;when the vapor pressure deficit(VPD)was>2000 Pa,the estimated CWSI was related to soil water conditions.The height of the installed infrared thermograph influenced the T_(c)values,and the differences among the T_(c)values measured at height of 3,5,and 10 m was smaller in the afternoon than in the morning.However,the lens of the thermometer facing south recorded a higher T_(c)than those facing east or north,especially at a low height,indicating that the direction of the thermometer had a significant influence on T_(c).There was a large variation in CWSI derived at different times of the day,and the midday measurements(12:00-15:00)were the most reliable for estimating CWSI.Negative linear relationships were found between the transpiration rate and CWSI-E(R^(2)of 0.3646-0.5725)and CWSI-T(R^(2)of 0.5407-0.7213).The relations between fraction of available soil water(FASW)with CWSI-T was higher than that with CWSI-E,indicating CWSI-T was more accurate for predicting crop water status.In addition,The R^(2)between CWSI-T and FASW at 14:00 was higher than that at other times,indicating that 14:00 was the optimal time for using the CWSI for crop water status monitoring.Relative higher yield of winter wheat was obtained with average seasonal values of CWSI-E and CWSI-T around 0.23 and 0.25-0.26,respectively.The CWSI-E values were more easily influenced by meteorological factors and the timing of the measurements,and using the theoretical approach to derive the CWSI was recommended for precise irrigation water management.展开更多
Electron thermal transport is one of the most complex processes in fusionplasmas. It is generally described by a simple thermal diffusivity in transport analyses ofdischarges, but there is evidence of critical gradien...Electron thermal transport is one of the most complex processes in fusionplasmas. It is generally described by a simple thermal diffusivity in transport analyses ofdischarges, but there is evidence of critical gradient effects with moderate stiffness. By analyzingperiodic perturbations to an equilibrium, one canmeasure the variations in electron energy flux andelectron temperature gradient over the perturbation cycle, obtaining the flux as a function ofgradient over the range of parameters generated by the perturbation. Although time-dependenttransport analysis is very sensitive to noise in the input data, averaging over many cycles of aperiodic perturbation can provide data of sufficient quality. The analyses presented here are basedon the ECE temperature data with high spatial and temporal resolution and full profile coverage onDIII-D for sawteeth and modulated ECH heating.展开更多
Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole direc...Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole directional coupler has been designed and manufactured for the 105 GHz/500 kW ECRH system on the J-TEXT tokamak.During the design process,we established the relationships between hole parameters and coupling characteristics based on the multi-hole coupling method and small-hole coupling theory.High-power tests have been carried out.The results indicated the reasonability of the theoretical design and practicality of the fabricated directional coupler.Sources of test errors have been discussed in detail,and the influences of spurious modes on the directional couplers have been emphatically analyzed.展开更多
The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring tr...The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.展开更多
The first stars in the early Universe were formed about 400 million years after the big bang. Verification of the existence of these stars is important for our understanding of the evolution of the Universe[1]. It has...The first stars in the early Universe were formed about 400 million years after the big bang. Verification of the existence of these stars is important for our understanding of the evolution of the Universe[1]. It has been predicted that for Population-III stellar production yields, the abundances of odd-Z elements are remarkably deficient compared to their adjacent even-Z elements[2]. Astronomers are searching for long-lived, low mass stars with the unique nucleosynthetic pattern matching the predicted yields[3].展开更多
The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 k...The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.展开更多
Background: Recently, increases in the risk of Hepatocellular carcinoma (HCC) recurrence in patients with hepatitis C virus (HCV) due to the administration of direct antivirals agents (DAA) have been reported. Methods...Background: Recently, increases in the risk of Hepatocellular carcinoma (HCC) recurrence in patients with hepatitis C virus (HCV) due to the administration of direct antivirals agents (DAA) have been reported. Methods: One hundred and nineteen patients who were treated with DAA and achieved sustained viral response (SVR) were prospectively followed-up for over two years by transient elastography with liver stiffness measurements (LSM). Fourteen out of 119 patients (12%) had a history of being treated for HCC by radiofrequency ablation or resection and achieved complete responses after previous HCC treatments before the initiation of DAA. HCC was diagnosed by contrast-enhanced computed tomography (CT) or enhanced magnetic resonance imaging (MR). CT or MR was performed before the DAA treatment and every 6 months after during the follow-up. LSM was performed at the initiation of DAA (LSM0), at 24 weeks after the start of DAA (LSM24), at 48 weeks after that (LSM48) and at 2 years after that (LSM2y). Results: LSM0, LSM24, LSM48 and LSM2y of 105 patients without HCC were 7.5 (3.027.0), 6.0 (2.5 - 31.6), 4.6 (2.6?- 25.2) and 4.4 (3.1 - 29.9) kPa, respectively, showing significant improvements. Three out of 105 patients (2.9%) subsequently developed HCC and their LSM showed improvements. Eight out of fourteen patients (57%) with a history of HCC treatments subsequently developed HCC recurrence. LSM0 in the eight patients with recurrence increasing from 12.1 to 27.0 kPa, LSM24 from 9.9 to 26.6 kPa and LSM48 from 9.6 to 18.0 kPa. On the other hand, the six other patients without recurrence had LSM values that were less than 12.0 kPa at last. Based on the ROC analysis, LSM0 15.4, LSM24 12.8 and LSM48 9.6 kPa were identified as cut-off values. Conclusion: HCV patients previously treated for HCC with high LSM values before and after DAA have an elevated risk of HCC recurrence, particularly LSM24 >12.8 kPa and LSM48 >9.6 kPa.展开更多
基金Project supported by National Key Research and Development Program of China (Grant No. 2019YFA0705000)the National Natural Science Foundation of China (Grant No. 11974178)。
文摘Efficient acquiring information from a quantum state is important for research in fundamental quantum physics and quantum information applications. Instead of using standard quantum state tomography method with reconstruction algorithm, weak values were proposed to directly measure density matrix elements of quantum state. Recently, similar to the concept of weak value, modular values were introduced to extend the direct measurement scheme to nonlocal quantum wavefunction. However, this method still involves approximations, which leads to inherent low precision. Here, we propose a new scheme which enables direct measurement for ideal value of the nonlocal density matrix element without taking approximations. Our scheme allows more accurate characterization of nonlocal quantum states, and therefore has greater advantages in practical measurement scenarios.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10274093 and 10474118, the National Fundamental Research Program under Grant No. 2001CB309309, the Natural Science Foundatioa of Hunan Province of China, the Science Research Fund of Educational Department of Hunan Province of China, the Science Research Fund of Hunan Institute of Humanity and Science and Technology under Grant No. 2005A008, and the Foundation for Youth Core-Teachers of Hunan Province under Grant No. 2003165
文摘A scheme for approximately and conditionally teleporting an unknown atomic state via two-photon interaction in cavity QED is proposed. It is the extension of the scheme of Ref. [11] [Phys. Rev. A 69 (2004) 064302], which is based on Jaynes-Cummings model in QED and where only a time point of system evolution and the corresponding fidelity implementing the teleportation are given. In our scheme, the two-photon interaction Jaynes-Cummings model is used to realize the approximate and conditional teleportation. Our scheme does not involve the Bell-state measurement and an additional atom, only requiring two atoms and one single-mode cavity. The fidelity of the scheme is higher than that of Ref. [11]. The scheme may be generalized to not only the teleportation of the state of a cavity mode to another mode by means of a single atom but also the teleportation of the state of a trapped ion.
文摘In a previous work [Commun. Theor. Phys. 45 (2006) 79] a scheme was presented for approximate and conditional teleportation of an unknown atomic state in a QED-cavity without Bell-state measurement via two-photon Jaynes-Cummings model in the effective Hamiltonian approach. This comment presents an alternative method, based on the so called "full two-photon Jaynes-Cummings Hamiltonian approach". Accordingly, it describes the evolution of the two-photon degenerate process for arbitrary average photon number inside the cavity, as the correct way to implement teleportation in this scenario.
基金Supported by the Natural Science Foundation of Jiangxi,China under Grant No.2008GQW0017the Scientific Research Foundation of Jiangxi Provincial Department of Education under Grant No.GJJ09504the Foundation of Talent of Jinggang of Jiangxi Province under Grant No.2008DQ00400
文摘We present a scheme in which the N-atom W state is teleported by employing the selective interactionof a cavity field with a driven three-level atom in the A configuration and detecting a single atom in one of the groundstates.The long-lived W state is teleported from atom A to atom B when the atoms B and A are sent through acavity successively and atom A is then detected.The advantage is that the present one does not involve the Bell-statemeasurement and is robust against the atomic spontaneous emission.
基金National Natural Science Foundation of China under Grant Nos.60678022 and 1070400the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20060357008+3 种基金Natural Science Foundation of Anhui Province under Grant No.070412060the Key Program of the Education Department of Anhui Province under Grant No.2006KJ070AThe Talent Foundation of Anhui UniversityAnhui Key Laboratory of Information Materials and Devices (Anhui University)
文摘An experimentally feasible scheme for teleportation of an unknown two-atom entangled state is proposed. Our scheme uses a duster state as the quantum channel, where we do not need any joint Bell-state measurement. Moreover the successful probability and fidelity of teleportation can both reach 1.0. The current scheme can be realized within the current experimental technology.
基金Project supported by the National Natural Science Foundation of China (Grant No 10374025).
文摘This paper proposes a scheme for information concentration of two remote two-level atoms in cavity QED. This scheme does not involve the Bell-state measurement. During the interaction between atom and cavity, the cavity frequency is large-detuned from the atomic transition frequency, thus the scheme is insensitive to both the cavity decay and the thermal field. This idea can directly be generalized in the case of multi-atom information concentration.
基金supported by National Natural Science Foundation of China under Grant No.10574022the Natural Science Foundation of Fujian Province under Grant No.Z0512006the Foundation of Education Commission of Fujian Province under Grant No.JB07043
文摘An alternative scheme is proposed for teleportation of an unknown atomic-entangled state. The scheme is based on the resonant interaction of a two-mode cavity field with a A-type three-level atom. In contrast with the previously proposed scheme of [Commun. Theor. Phys. 47 (2007) 253], the present scheme is ascendant, since the fidelity is 1.0 in principle similarly without the Bell-state measurement. The scheme may be generalized to not only the teleportation of the cavity-mode-entangled-state but also the teleportation of the multi-atomic entangled states included in generalized GHZ states. And the scheme is experimentally feasible based on the current cavity QED technique.
基金The project supported by Natural Science Foundation of Hunan Province under Grant No. 05JJ30005, the Science Research Fund of Education Bureau of Hunan Province under Grant No. 05C756, National Naturai Science FoUndation of China under Grant Nos. 10274093 and 10474118, the Foundation for Youth Core-Teachers of Hunan Province under Grant No. 2003165, and the Science Research Fund of Hunan Institute of Humanity and Science and Technology under Grant N01 2004A014
文摘A scheme for approximately and conditionally teleporting an unknown atomic-entangled state in cavity QED is proposed. It is the novel extension of the scheme of [Phys. Rev. A 69 (200,I) 06,1302], where the state to be teleported is an unknown atomic state and where only a time point of system evolution and the corresponding: fidelity implementing the telèportation are given. In fact, there exists multi-time points and the corresponding fidelities, which are Shown in this paper and then are used to realize the approximate and conditional teleportation of the unknown atomic-entangled state. Naturally, our scheme does not involve the Bell-state measurement or an additional atom, which is required in the Bell-state measurement, only requiring one single-mode cavity. The scheme may be generalized to not only the teleportation of the cavity-mode-entangled-state by means of a single atom but also the teleportation of the unknown trapped-ion-entangled-state in a linear ion trap and the teleportation of the multi-atomic entangled states included in generalized GHZ states.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61068001 and 11064016)
文摘We propose a protocol to implement the nonlocal Bell-state measurement, which is nearly determinate with the help of weak cross-Kerr nonlinearities and quantum non-destructive photon number resolving detection. Based on the nonlocal Bell-state measurement, we implement the quantum information transfer from one place to another. The process is different from conventional teleportation but can be regarded as a novel form of teleportation without entangled channel and classic communication.
基金Supported by the Natural Science Research Programme of the Education Department of Anhui Province under Grant Nos.KJ2009B039Z and KJ2009B018Zthe Municipal Level Research Project from Lu'an City directive entrusted to West AnHui University under Grant No.2008LW004
文摘We propose a scheme for sharing an arbitrary unknown two-qubit state among three parties by using afour-qubit cluster-class state and a Bell state as a quantum channel With a quantum controlled phase gate (QCPG)operation and a local unitary operation,any one of the two agents has the access to reconstruct the original state ifhe/she collaborates with the other one,whilst individual agent obtains no information.As all quantum resource canbe used to carry the useful information,the intrinsic efficiency of qubits approaches the maximal value.Moreover,thepresent scheme is more feasible with present-day technique.
文摘Measuring multi-directional waves with the wave gauge array is one of the fundamental and easily realised methods. In this paper, the wave gauge array is described and the effects of the gauge spacing, the array orientations, etc. of the three array arrangements, i. e., linear array, T-type array and pentagon array, on the resolution of the directional spreading of waves, are investigated experimentally. This study can be used as a reference in the experimental study and the field measurement of directional waves.
基金supported by the National Natural Science Foundation of China(Grant No.11272338)the Science and Technology on Scramjet Key Laboratory Funding,China(Grant No.STSKFKT 2013004)the China Scholarship Council
文摘An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence(LIF)methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar flame. In our approach, particular attention is paid to the linear laser-induced fluorescence and absorption processes, and experimental details as well. Through measuring the temperature, LIF signal distribution and integrated absorption, spatially absolute OH concentrations profiles are successfully resolved. These experimental results are then compared with the numerical simulation. It is proved that the good quality of the results implies that this method is suitable for calibrating the OH-PLIF measurement in a practical combustor.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974189 and 12175106)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.20KJB140001)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grand No.KYCX22-0963)
文摘The one-step quantum secure direct communication(QSDC)(Sci.Bull.67,367(2022))can effectively simplify QSDC’s operation and reduce message loss.For enhancing its security under practical experimental condition,we propose two measurement-device-independent(MDI)one-step QSDC protocols,which can resist all possible attacks from imperfect measurement devices.In both protocols,the communication parties prepare identical polarization-spatial-mode two-photon hyperentangled states and construct the hyperentanglement channel by hyperentanglement swapping.The first MDI one-step QSDC protocol adopts the nonlinear-optical complete hyperentanglement Bell state measurement(HBSM)to construct the hyperentanglement channel,while the second protocol adopts the linear-optical partial HBSM.Then,the parties encode the photons in the polarization degree of freedom and send them to the third party for the hyperentanglementassisted complete polarization Bell state measurement.Both protocols are unconditionally secure in theory.The simulation results show the MDI one-step QSDC protocol with complete HBSM attains the maximal communication distance of about354 km.Our MDI one-step QSDC protocols may have potential applications in the future quantum secure communication field.
基金supported by the Project of State Grid Hebei Electric Power Co.,Ltd.(SGHEYX00SCJS2100077).
文摘Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the influences of atmospheric conditions,settled height,view angle of infrared thermography,and investigating time of temperature measuring on the performance of the CWSI.Three irrigation treatments were used to create different soil water conditions during the 2020-2021 and 2021-2022 winter wheat-growing seasons.The CWSI was calculated using the CWSI-E(an empirical approach)and CWSI-T(a theoretical approach)based on the T_(c).Weather conditions were recorded continuously throughout the experimental period.The results showed that atmospheric conditions influenced the estimation of the CWSI;when the vapor pressure deficit(VPD)was>2000 Pa,the estimated CWSI was related to soil water conditions.The height of the installed infrared thermograph influenced the T_(c)values,and the differences among the T_(c)values measured at height of 3,5,and 10 m was smaller in the afternoon than in the morning.However,the lens of the thermometer facing south recorded a higher T_(c)than those facing east or north,especially at a low height,indicating that the direction of the thermometer had a significant influence on T_(c).There was a large variation in CWSI derived at different times of the day,and the midday measurements(12:00-15:00)were the most reliable for estimating CWSI.Negative linear relationships were found between the transpiration rate and CWSI-E(R^(2)of 0.3646-0.5725)and CWSI-T(R^(2)of 0.5407-0.7213).The relations between fraction of available soil water(FASW)with CWSI-T was higher than that with CWSI-E,indicating CWSI-T was more accurate for predicting crop water status.In addition,The R^(2)between CWSI-T and FASW at 14:00 was higher than that at other times,indicating that 14:00 was the optimal time for using the CWSI for crop water status monitoring.Relative higher yield of winter wheat was obtained with average seasonal values of CWSI-E and CWSI-T around 0.23 and 0.25-0.26,respectively.The CWSI-E values were more easily influenced by meteorological factors and the timing of the measurements,and using the theoretical approach to derive the CWSI was recommended for precise irrigation water management.
基金the US Department of Energy under grant DE-FG03-97-ER54415
文摘Electron thermal transport is one of the most complex processes in fusionplasmas. It is generally described by a simple thermal diffusivity in transport analyses ofdischarges, but there is evidence of critical gradient effects with moderate stiffness. By analyzingperiodic perturbations to an equilibrium, one canmeasure the variations in electron energy flux andelectron temperature gradient over the perturbation cycle, obtaining the flux as a function ofgradient over the range of parameters generated by the perturbation. Although time-dependenttransport analysis is very sensitive to noise in the input data, averaging over many cycles of aperiodic perturbation can provide data of sufficient quality. The analyses presented here are basedon the ECE temperature data with high spatial and temporal resolution and full profile coverage onDIII-D for sawteeth and modulated ECH heating.
基金supported by the National Key Research and Development Program of China (Nos.2017YFE0300200 and 2017YFE0300204)in part by National Natural Science Foundation of China(No.51821005).
文摘Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole directional coupler has been designed and manufactured for the 105 GHz/500 kW ECRH system on the J-TEXT tokamak.During the design process,we established the relationships between hole parameters and coupling characteristics based on the multi-hole coupling method and small-hole coupling theory.High-power tests have been carried out.The results indicated the reasonability of the theoretical design and practicality of the fabricated directional coupler.Sources of test errors have been discussed in detail,and the influences of spurious modes on the directional couplers have been emphatically analyzed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91336103,10934010 and 61078026
文摘The optical frequency comb has been widely used in precision measurement. In this study, a multi-peak fitting approach is first proposed to fit the two-photon transition spectrum which overlaps with the neighboring transition in Rb-87. The multi-peak fitting approach is used to eliminate the frequency shift affected by the neighboring transition. With locking the carrier envelope offset frequency at 1/4 repetition frequency, the transition frequency is measured to be 770569132739.9 +/- 5.8 kHz, which agrees well with the previous result recommended by Comite International des Poids et Mesures.
文摘The first stars in the early Universe were formed about 400 million years after the big bang. Verification of the existence of these stars is important for our understanding of the evolution of the Universe[1]. It has been predicted that for Population-III stellar production yields, the abundances of odd-Z elements are remarkably deficient compared to their adjacent even-Z elements[2]. Astronomers are searching for long-lived, low mass stars with the unique nucleosynthetic pattern matching the predicted yields[3].
文摘The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.
文摘Background: Recently, increases in the risk of Hepatocellular carcinoma (HCC) recurrence in patients with hepatitis C virus (HCV) due to the administration of direct antivirals agents (DAA) have been reported. Methods: One hundred and nineteen patients who were treated with DAA and achieved sustained viral response (SVR) were prospectively followed-up for over two years by transient elastography with liver stiffness measurements (LSM). Fourteen out of 119 patients (12%) had a history of being treated for HCC by radiofrequency ablation or resection and achieved complete responses after previous HCC treatments before the initiation of DAA. HCC was diagnosed by contrast-enhanced computed tomography (CT) or enhanced magnetic resonance imaging (MR). CT or MR was performed before the DAA treatment and every 6 months after during the follow-up. LSM was performed at the initiation of DAA (LSM0), at 24 weeks after the start of DAA (LSM24), at 48 weeks after that (LSM48) and at 2 years after that (LSM2y). Results: LSM0, LSM24, LSM48 and LSM2y of 105 patients without HCC were 7.5 (3.027.0), 6.0 (2.5 - 31.6), 4.6 (2.6?- 25.2) and 4.4 (3.1 - 29.9) kPa, respectively, showing significant improvements. Three out of 105 patients (2.9%) subsequently developed HCC and their LSM showed improvements. Eight out of fourteen patients (57%) with a history of HCC treatments subsequently developed HCC recurrence. LSM0 in the eight patients with recurrence increasing from 12.1 to 27.0 kPa, LSM24 from 9.9 to 26.6 kPa and LSM48 from 9.6 to 18.0 kPa. On the other hand, the six other patients without recurrence had LSM values that were less than 12.0 kPa at last. Based on the ROC analysis, LSM0 15.4, LSM24 12.8 and LSM48 9.6 kPa were identified as cut-off values. Conclusion: HCV patients previously treated for HCC with high LSM values before and after DAA have an elevated risk of HCC recurrence, particularly LSM24 >12.8 kPa and LSM48 >9.6 kPa.