We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In n...We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In nonlinear electrodynamics,strong electromagnetic fields modify the vacuum such that it acquires optical properties.Such a field-modified vacuum can possess electric permittivity,magnetic permeability,and a magneto-electric response,inducing novel phenomena such as vacuum birefringence.By exploiting the mathematical structures of Plebanski-type Lagrangians,we establish a streamlined procedure and explicit formulas to determine light modes,i.e.,refractive indices and polarization vectors for a given propagation direction.We also work out the light modes of the various Lagrangians for an arbitrarily strong magnetic field.The 3+1 formulation advanced in this paper has direct applications to the current vacuum birefringence research:terrestrial experiments using permanent magnets/ultra-intense lasers for the subcritical regime and astrophysical observation of X-rays from highly magnetized neutron stars for the near-critical and supercritical regimes.展开更多
A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine...A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine feet vibrations is presented.First,a generalized mathematical formulation is derived based on a state-space description which can be used for different kinds of models(1D,2D,and 3D models).It is shown that under special boundary conditions,the control parameters can be directly implemented into the stiffness and damping matrices of the system.Based on the generalized mathematical formulation,an example of a rotating machine—described by a 2D model—with journal bearings,flexible rotor,current-controlled electrodynamic actuators,steel frame foundation,and velocity feedback of the machine feet vibrations is presented where the effectiveness of the described active vibration control system is demonstrated.展开更多
The space debris occupies the orbit resources greatly,which seriously threats the safety of spacecraft for its high risks of collisions.Many theories about space debris removal have been put forward in recent years.Th...The space debris occupies the orbit resources greatly,which seriously threats the safety of spacecraft for its high risks of collisions.Many theories about space debris removal have been put forward in recent years.The Electro Dynamic Tether(EDT),which can be deployed under gravity gradient,is considered to be an effective method to remove debris in low orbit for its low power consumption.However,in order to generate sufficient Lorentz force,the EDT needs to be deployed to several kilometers,which increases the risks of tangling and the instability of the EDT system.In the deployment process,different initial in-plane/out-of-plane angles,caused by direction error at initial release or the initial selection of ejection,affect the motion of EDT system seriously.In order to solve these problems,firstly,this paper establishes the dynamic model of the EDT system.Then,based on the model,safety metrics of avoiding tangling and assessing system stability during EDT deployment stage are designed to quantitatively evaluate the EDT system security.Finally,several numerical simulations are established to determine the safety ranges of the initial in-plane/out-of-plane angles on the EDT deployment.展开更多
This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly ...This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly appears during daytime in summer hemispheres, and is formed primarily from neutral wind shear in the mesosphere and lower thermosphere(MLT) region. Field-aligned irregularity(FAI) in the E region is also observed by Very High Frequency(VHF) radar in mid-latitude regions. FAI frequently occurs after sunset in summer hemispheres, and spectrum features of E region FAI echoes suggest that type-2 irregularity is dominant in the nighttime ionosphere. A close relationship between ES and E region FAI implies that ES may be a possible source of E region FAI in the nighttime ionosphere. Strong neutral wind shear, steep ES plasma density gradient, and a polarized electric field are the significant factors affecting the formation of E region FAI. At mid-latitudes, joint observational experiments including ionosonde, VHF radar, Global Positioning System(GPS) stations, and all-sky optical images have revealed strong connections across different scales of ionospheric irregularities in the nighttime F region, such as spread F(SF), medium-scale traveling ionospheric disturbances(MSTID), and F region FAI.Observations suggest that different scales of ionospheric irregularities are generally attributed to the Perkins instability and subsequently excited gradient drift instability. Nighttime MSTID can further evolve into small-scale structures through a nonlinear cascade process when a steep plasma density gradient exists at the bottom of the F region. In addition, the effect of ionospheric electrodynamic coupling processes, including ionospheric E-F coupling and inter-hemispheric coupling on the generation of ionospheric irregularities, becomes more prominent due to the significant dip angle and equipotentiality of magnetic field lines in the mid-latitude ionosphere. Polarized electric fields can map to different ionospheric regions and excite plasma instabilities which form ionospheric irregularities. Nevertheless,the mapping efficiency of a polarized electric field depends on the ionospheric background and spatial scale of the field.展开更多
In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the ...In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the service characteristics of the restored products.Residual stresses arise as a result of welding.Post-weld heat treatment is used to reduce the residual stresses.The heat treatment,which occurs after welding,increases the cost of repair.This leads to the search for alternative methods to control the stressed state of welded joints,one of which is electrodynamic treatment,which reduces the level of residual stresses in repair welds,and as a consequence,the cost of the welding repair in restoring aircraft structures.It was found from the results of experiments carried out,that the electrodynamic treatment allows reduces the initial level of stresses in welded joints,reaching 120 MPa,to 30 MPa,and at definite geometric characteristics of the specimens forming the field of compressive stresses,the values ofwhich are equal to-50 MPa.It is shown that the optimum distance between the zones of treatment,being 5 mm,provides the guaranteed covering the zones of electrodynamic effect and,as a consequence,the maximum efficiency of the electric dynamic treatment.展开更多
An energy-based controller of electric current is synthesized for the libration stabilization of an electrodynamic tether system,which consists of a relatively large main-satellite and a sub-satellite of much smaller ...An energy-based controller of electric current is synthesized for the libration stabilization of an electrodynamic tether system,which consists of a relatively large main-satellite and a sub-satellite of much smaller size.Two dynamic models with different levels of accuracy are considered in this work.First,a dumbbell model of the system is used for the controller design,which aims at damping injection on the libration motions via the real-time regulation of the electric current.Furthermore,the efficacy and performance of the proposed scheme are numerically verified by using a more complex multi-body model which accounts for not only the tether flexibility but also the attitude of the main-satellite.展开更多
In this paper we investigate the scalar field evolution in the dyadosphere spacetime by using the third-order WKB approximation. We find that the coupling term between the gravitation and the nonlinear electrodynamics...In this paper we investigate the scalar field evolution in the dyadosphere spacetime by using the third-order WKB approximation. We find that the coupling term between the gravitation and the nonlinear electrodynamics makes the scalar field decay more quickly and it also makes the scalar field oscillate more slowly. On the o＇ther words, this coupling term takes effect on the scalar field evolution as a damping factor. At the same time these effects become more obvious for the scalar field with higher angle quantum number.展开更多
We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependen...We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependent on the phase of atomic radiation and the speeding up of collective decay can only be observed in a bad cavity regime. For in-or out-phase case,this occurs due to the quantum interference enhancement, no matter which atom is excited initially. For π/2 phase, the speeding up of collective decay takes place if the first atom is excited at the beginning. However, it disappears due to the quantum interference cancellation if the second atom is excited. Compared with the in-phase and out-phase cases,we also show that the speeding up of collective decay can be significantly enhanced in strong coupling regime for π/2 phase, although one atom is decoupled to the cavity in this condition. The study presented here is helpful to understand the physical mechanism of collective decay in cavity quantum electrodynamics and it provides a useful method to control the collective decay phenomenon via quantum interference effect.展开更多
An expression of the generalized principle of virtual work for the boundary value problem of the linear and anisotropic electromagnetic field is given. Using Chien＇s method, a pair of generalized variational principl...An expression of the generalized principle of virtual work for the boundary value problem of the linear and anisotropic electromagnetic field is given. Using Chien＇s method, a pair of generalized variational principles （GVPs） are established, which directly leads to all four Maxwell＇s equations, two intensity-potential equations, two constitutive equations, and eight boundary conditions. A family of constrained variational principles is derived sequentially. As additional verifications, two degenerated forms are obtained, equivalent to two known variational principles. Two modified GVPs are given to provide the hybrid finite element models for the present problem.展开更多
We theoretically study the system of a superconducting transmission line resonator coupled to two interacting super- conducting flux qubits. It is shown that under certain conditions the resonator mode can be tuned to...We theoretically study the system of a superconducting transmission line resonator coupled to two interacting super- conducting flux qubits. It is shown that under certain conditions the resonator mode can be tuned to two-photon resonance between the ground state and the highest excited state while the middle excited states are far-off resonance. Furthermore, we study the steady-state properties of the flux qubits and resonator, such as the photon statistics, the spectrum and squeezing of the resonator, and demonstrate that two-photon laser can be implemented with current experimental technology.展开更多
In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and...In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and the qubit decoherence rate and point out the optimized operating position of the hybrid system.According to the transmission given by the input-output theory,the signatures in the resonator spectrum are predicted.Furthermore,based on the parameters already achieved in previous works,we prove that the device described in this paper can achieve the strong coupling limit,i.e.,this approach can be used for system extension under the existing technical conditions.Our results show an effective and promotable approach to couple quantum dot structures in plane with the resonator and propose a meaningful extension method.展开更多
This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity. The scheme is based on the dispersive atom-cavity interaction. By modulating the cavity frequency and the atomic transition freq...This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity. The scheme is based on the dispersive atom-cavity interaction. By modulating the cavity frequency and the atomic transition frequency appropriately, it obtains the effective form of nonlinear interaction between photons in the three-mode cavity. This availability is testified via numerical analysis. It also considers both the situations with and without dissipation.展开更多
Undesirable repulsive force between contact members due to both a current path shrink near a real contact area and/or so-called pinch effect is particularly onerous for power switch applications, and results in either...Undesirable repulsive force between contact members due to both a current path shrink near a real contact area and/or so-called pinch effect is particularly onerous for power switch applications, and results in either contact floating or bouncing which are associated with an electric arc following contact welding. This problem is of great importance for any circuit breaker especially for compact low voltage vacuum circuit breakers. To avoid contact floating at closure and during any inrush current under short circuit conditions, the electrodynamic repulsive force can be employed successfully if we use a special compensation system flexibly combined with the contact itself. However to select and design the compensation system properly, its efficiency has to be known. This paper presents an approach to obtain the electrodynamic force value depending on different shaped (rectangular, square, circle and arch) copper plates used in the compensator by using ANSYS for current values 40 kA RMS. Curve-fitting was done according to the calculating results, the optimization designing of compensation unit is based on them.展开更多
Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation...Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron– laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of γ-ray laser generation by use of this kind of collision is discussed.展开更多
There exist a lot of controversial issues around the subject of SW(Scalar Waves)and the purpose of this white paper is to take an innovative theoretical approach to prove and backup up existence of such phenomena.We b...There exist a lot of controversial issues around the subject of SW(Scalar Waves)and the purpose of this white paper is to take an innovative theoretical approach to prove and backup up existence of such phenomena.We basically define this wave as a SLW(Scalar Longitudinal Wave),whose existence derives from the MCE(More Complete Electrodynamic)theory aspect of Maxwell’s classical electrodynamic equations.MCE falls into the QED(Quantum Electrodynamic)aspect of the Maxwell’s equations,in particular out of his four famous classical equations,our interest focuses on the one that is known to us as Faraday’s Law of the Maxwell’s Equation set.展开更多
In this paper,we study the thermodynamics and the weak cosmic censorship conjecture of the nonlinear electrodynamics black hole under the scattering of a charged complex scalar field.According to the energy and charge...In this paper,we study the thermodynamics and the weak cosmic censorship conjecture of the nonlinear electrodynamics black hole under the scattering of a charged complex scalar field.According to the energy and charge fluxes of the scalar field,the variations of this black hole’s energy and charge can be calculated during an infinitesimal time interval.With scalar field scattering,the variation of the black hole is calculated in the extended and normal phase spaces.In the normal phase space,the cosmological constant and the normalization parameter are fixed,and the first and second laws of thermodynamics can also be satisfied.In the extended phase space,the cosmological constant and the normalization parameter are considered as thermodynamic variables,and the first law of thermodynamics is valid,but the second law of thermodynamics is not valid.Furthermore,the weak cosmic censorship conjecture is both valid in the extended and normal phase spaces.展开更多
By introducing Oseen's formula to describe the viscous drag force, a more complete motion equation for a charged microparticle levitated in an electrodynamic balance (EDB) has been put forward and solved numerical...By introducing Oseen's formula to describe the viscous drag force, a more complete motion equation for a charged microparticle levitated in an electrodynamic balance (EDB) has been put forward and solved numerically by the classic Runge-Kutta method in this paper. The theoretical results have firstly demonstrated the existence of the particle oscillations and their characteristics, especially of the springpoint oscillation at large amplitude. And through the comparisons of theoretical and experimental trajectories, the adopted motion equation has proved to be able to rigorously describe the particle motion in non-Stokes region-the shape of trajectory and frequency characteristics are fairly consistent and the deviations of amplitude can usually be less than 10%.展开更多
In the design realm of fusion power supplies,structural components play a pivotal role in ensuring the safety of fusion devices.To verify the reliability of the converter structure design at the Comprehensive Research...In the design realm of fusion power supplies,structural components play a pivotal role in ensuring the safety of fusion devices.To verify the reliability of the converter structure design at the Comprehensive Research Facility for Fusion Technology(CRAFT),meticulous analysis of the converter's dynamic impact is carefully performed based on the worst fault current(400k A),firstly.Subsequently,the thermal stress analysis based on the maximum allowable steadystate temperature is finished,and the equivalent thermal stress,thermal deformation,maximum shear stress of a single bridge arm and the whole converter are studied.Furthermore,a simple research method involving the current-sharing characteristics of a bridge arm with multithyristor parallel connection is proposed using a combination of Simplorer with Q3D in ANSYS.The results show that the current-sharing characteristics are excellent.Finally,the structural design has been meticulously tailored to meet the established requirements.展开更多
We calculate the scattering cross section of an electron with respect to the spontaneously produced laser radiation in the first free-electron laser （FEL） with quantum-wiggler electrodynamics （QWD）. The cross sect...We calculate the scattering cross section of an electron with respect to the spontaneously produced laser radiation in the first free-electron laser （FEL） with quantum-wiggler electrodynamics （QWD）. The cross section is 1016 times the Thomson cross section, confirming the result obtained by a previous analysis of the experimental data. A QWD calculation show that spontaneous emission in an FEL using only an electric wiggler can be very strong while amplification through net stimulated emission is practically negligible.展开更多
This theory aims beyond the possibilities being available from the Standard Model. Examples are given by the directly obtained rest masses of the elementary particles, the deduced values of the elementary charge and o...This theory aims beyond the possibilities being available from the Standard Model. Examples are given by the directly obtained rest masses of the elementary particles, the deduced values of the elementary charge and of the mass of the boson detected by CERN which are close to their experimental data, and by an incorporated spin of the photon.展开更多
基金supported by the Ultrashort Quantum Beam Facility operation program(Grant No.140011)through APRI,GISTalso by the Institute of Basic Science(Grant No.IBSR038-D1).
文摘We present a 3+1 formulation of the light modes in nonlinear electrodynamics described by Plebanski-type Lagrangians,which include post-Maxwellian,Born-Infeld,ModMax,and Heisenberg-Euler-Schwinger QED Lagrangians.In nonlinear electrodynamics,strong electromagnetic fields modify the vacuum such that it acquires optical properties.Such a field-modified vacuum can possess electric permittivity,magnetic permeability,and a magneto-electric response,inducing novel phenomena such as vacuum birefringence.By exploiting the mathematical structures of Plebanski-type Lagrangians,we establish a streamlined procedure and explicit formulas to determine light modes,i.e.,refractive indices and polarization vectors for a given propagation direction.We also work out the light modes of the various Lagrangians for an arbitrarily strong magnetic field.The 3+1 formulation advanced in this paper has direct applications to the current vacuum birefringence research:terrestrial experiments using permanent magnets/ultra-intense lasers for the subcritical regime and astrophysical observation of X-rays from highly magnetized neutron stars for the near-critical and supercritical regimes.
文摘A theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine feet vibrations is presented.First,a generalized mathematical formulation is derived based on a state-space description which can be used for different kinds of models(1D,2D,and 3D models).It is shown that under special boundary conditions,the control parameters can be directly implemented into the stiffness and damping matrices of the system.Based on the generalized mathematical formulation,an example of a rotating machine—described by a 2D model—with journal bearings,flexible rotor,current-controlled electrodynamic actuators,steel frame foundation,and velocity feedback of the machine feet vibrations is presented where the effectiveness of the described active vibration control system is demonstrated.
基金co-supported by the National Natural Science Foundation of China(Nos.51975021,U1913206)。
文摘The space debris occupies the orbit resources greatly,which seriously threats the safety of spacecraft for its high risks of collisions.Many theories about space debris removal have been put forward in recent years.The Electro Dynamic Tether(EDT),which can be deployed under gravity gradient,is considered to be an effective method to remove debris in low orbit for its low power consumption.However,in order to generate sufficient Lorentz force,the EDT needs to be deployed to several kilometers,which increases the risks of tangling and the instability of the EDT system.In the deployment process,different initial in-plane/out-of-plane angles,caused by direction error at initial release or the initial selection of ejection,affect the motion of EDT system seriously.In order to solve these problems,firstly,this paper establishes the dynamic model of the EDT system.Then,based on the model,safety metrics of avoiding tangling and assessing system stability during EDT deployment stage are designed to quantitatively evaluate the EDT system security.Finally,several numerical simulations are established to determine the safety ranges of the initial in-plane/out-of-plane angles on the EDT deployment.
基金supported by the National Natural Science Foundation of China (No. 41574146, 41774162, 42074187)the National Key R&D Program of China (No. 2018YFC1503506)+1 种基金the Excellent Youth Foundation of Hubei Provincial Natural Science Foundation (No. 2019CFA054)the Foundation of the National Key Laboratory of Electromagnetic Environment (No. 20200101)。
文摘This paper briefly reviews ionospheric irregularities that occur in the E and F regions at mid-latitudes. Sporadic E(ES) is a common ionospheric irregularity phenomenon that is first noticed in the E layer. ES mainly appears during daytime in summer hemispheres, and is formed primarily from neutral wind shear in the mesosphere and lower thermosphere(MLT) region. Field-aligned irregularity(FAI) in the E region is also observed by Very High Frequency(VHF) radar in mid-latitude regions. FAI frequently occurs after sunset in summer hemispheres, and spectrum features of E region FAI echoes suggest that type-2 irregularity is dominant in the nighttime ionosphere. A close relationship between ES and E region FAI implies that ES may be a possible source of E region FAI in the nighttime ionosphere. Strong neutral wind shear, steep ES plasma density gradient, and a polarized electric field are the significant factors affecting the formation of E region FAI. At mid-latitudes, joint observational experiments including ionosonde, VHF radar, Global Positioning System(GPS) stations, and all-sky optical images have revealed strong connections across different scales of ionospheric irregularities in the nighttime F region, such as spread F(SF), medium-scale traveling ionospheric disturbances(MSTID), and F region FAI.Observations suggest that different scales of ionospheric irregularities are generally attributed to the Perkins instability and subsequently excited gradient drift instability. Nighttime MSTID can further evolve into small-scale structures through a nonlinear cascade process when a steep plasma density gradient exists at the bottom of the F region. In addition, the effect of ionospheric electrodynamic coupling processes, including ionospheric E-F coupling and inter-hemispheric coupling on the generation of ionospheric irregularities, becomes more prominent due to the significant dip angle and equipotentiality of magnetic field lines in the mid-latitude ionosphere. Polarized electric fields can map to different ionospheric regions and excite plasma instabilities which form ionospheric irregularities. Nevertheless,the mapping efficiency of a polarized electric field depends on the ionospheric background and spatial scale of the field.
文摘In repair of aircraft structures of magnesium alloy ML10,the argon arc non-consumable electrode welding is used.In this case,the residual welding stresses occur in repairwelds,being one of the causes for reducing the service characteristics of the restored products.Residual stresses arise as a result of welding.Post-weld heat treatment is used to reduce the residual stresses.The heat treatment,which occurs after welding,increases the cost of repair.This leads to the search for alternative methods to control the stressed state of welded joints,one of which is electrodynamic treatment,which reduces the level of residual stresses in repair welds,and as a consequence,the cost of the welding repair in restoring aircraft structures.It was found from the results of experiments carried out,that the electrodynamic treatment allows reduces the initial level of stresses in welded joints,reaching 120 MPa,to 30 MPa,and at definite geometric characteristics of the specimens forming the field of compressive stresses,the values ofwhich are equal to-50 MPa.It is shown that the optimum distance between the zones of treatment,being 5 mm,provides the guaranteed covering the zones of electrodynamic effect and,as a consequence,the maximum efficiency of the electric dynamic treatment.
基金Supported by the National Natural Science Foundation of China(11002068)the Foundation for the Author of National Excellent Doctoral Dissertation of China(201233)
文摘An energy-based controller of electric current is synthesized for the libration stabilization of an electrodynamic tether system,which consists of a relatively large main-satellite and a sub-satellite of much smaller size.Two dynamic models with different levels of accuracy are considered in this work.First,a dumbbell model of the system is used for the controller design,which aims at damping injection on the libration motions via the real-time regulation of the electric current.Furthermore,the efficacy and performance of the proposed scheme are numerically verified by using a more complex multi-body model which accounts for not only the tether flexibility but also the attitude of the main-satellite.
基金Supported by the National Natural Science Foundation of China under Grant No.10873004the Program for Excellent Talents in Hunan Normal University,the State Key Development Program for Basic Research Program of China under Grant No.2010CB832803+1 种基金the Key project of the National Natural Science Foundation of China under Grant No.10935013Construct Program of the National Key Discipline and the Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT0964
文摘In this paper we investigate the scalar field evolution in the dyadosphere spacetime by using the third-order WKB approximation. We find that the coupling term between the gravitation and the nonlinear electrodynamics makes the scalar field decay more quickly and it also makes the scalar field oscillate more slowly. On the o＇ther words, this coupling term takes effect on the scalar field evolution as a damping factor. At the same time these effects become more obvious for the scalar field with higher angle quantum number.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504272,11774262,11474003,and 11504003)the National Key Basic Research Special Foundation(Grant No.2016YFA0302800)+2 种基金the Joint Fund of the National Natural Science Foundation of China(Grant No.U1330203)the Fund from the Shanghai Science and Technology Committee(STCSM)(Grant No.18JC1410900)the Natural Science Foundation of Anhui Province,China(Grant Nos.1408085MA19 and 1608085ME102)
文摘We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependent on the phase of atomic radiation and the speeding up of collective decay can only be observed in a bad cavity regime. For in-or out-phase case,this occurs due to the quantum interference enhancement, no matter which atom is excited initially. For π/2 phase, the speeding up of collective decay takes place if the first atom is excited at the beginning. However, it disappears due to the quantum interference cancellation if the second atom is excited. Compared with the in-phase and out-phase cases,we also show that the speeding up of collective decay can be significantly enhanced in strong coupling regime for π/2 phase, although one atom is decoupled to the cavity in this condition. The study presented here is helpful to understand the physical mechanism of collective decay in cavity quantum electrodynamics and it provides a useful method to control the collective decay phenomenon via quantum interference effect.
基金Project supported by the National Natural Science Foundation of China （No. 60304009） and the Natural Science Foundation of Hebei Province of China （No. F2005000385）
文摘An expression of the generalized principle of virtual work for the boundary value problem of the linear and anisotropic electromagnetic field is given. Using Chien＇s method, a pair of generalized variational principles （GVPs） are established, which directly leads to all four Maxwell＇s equations, two intensity-potential equations, two constitutive equations, and eight boundary conditions. A family of constrained variational principles is derived sequentially. As additional verifications, two degenerated forms are obtained, equivalent to two known variational principles. Two modified GVPs are given to provide the hybrid finite element models for the present problem.
基金Project supported by the National Fundamental Research Program of China(Grant No.2011cba00200)the National Natural Science Foundation of China(Grant No.11274295)the Doctor Foundation of Education Ministry of China(Grant No.20113402110059)
文摘We theoretically study the system of a superconducting transmission line resonator coupled to two interacting super- conducting flux qubits. It is shown that under certain conditions the resonator mode can be tuned to two-photon resonance between the ground state and the highest excited state while the middle excited states are far-off resonance. Furthermore, we study the steady-state properties of the flux qubits and resonator, such as the photon statistics, the spectrum and squeezing of the resonator, and demonstrate that two-photon laser can be implemented with current experimental technology.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92265113,12074368,and 12034018).
文摘In this theoretical work,we describe a mechanism for the coupling between a plane structure consisting of four quantum dots and a resonator.We systematically study the dependence of the quadruple coupling strength and the qubit decoherence rate and point out the optimized operating position of the hybrid system.According to the transmission given by the input-output theory,the signatures in the resonator spectrum are predicted.Furthermore,based on the parameters already achieved in previous works,we prove that the device described in this paper can achieve the strong coupling limit,i.e.,this approach can be used for system extension under the existing technical conditions.Our results show an effective and promotable approach to couple quantum dot structures in plane with the resonator and propose a meaningful extension method.
基金supported by the National Natural Science Foundation of China (Grant No 60667001)
文摘This paper presents a scheme for implementing a Fredkin gate on three modes of a cavity. The scheme is based on the dispersive atom-cavity interaction. By modulating the cavity frequency and the atomic transition frequency appropriately, it obtains the effective form of nonlinear interaction between photons in the three-mode cavity. This availability is testified via numerical analysis. It also considers both the situations with and without dissipation.
文摘Undesirable repulsive force between contact members due to both a current path shrink near a real contact area and/or so-called pinch effect is particularly onerous for power switch applications, and results in either contact floating or bouncing which are associated with an electric arc following contact welding. This problem is of great importance for any circuit breaker especially for compact low voltage vacuum circuit breakers. To avoid contact floating at closure and during any inrush current under short circuit conditions, the electrodynamic repulsive force can be employed successfully if we use a special compensation system flexibly combined with the contact itself. However to select and design the compensation system properly, its efficiency has to be known. This paper presents an approach to obtain the electrodynamic force value depending on different shaped (rectangular, square, circle and arch) copper plates used in the compensator by using ANSYS for current values 40 kA RMS. Curve-fitting was done according to the calculating results, the optimization designing of compensation unit is based on them.
基金Project supported by the National Natural Science Foundation of China （Grant No. 10875003）.
文摘Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron– laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of γ-ray laser generation by use of this kind of collision is discussed.
文摘There exist a lot of controversial issues around the subject of SW(Scalar Waves)and the purpose of this white paper is to take an innovative theoretical approach to prove and backup up existence of such phenomena.We basically define this wave as a SLW(Scalar Longitudinal Wave),whose existence derives from the MCE(More Complete Electrodynamic)theory aspect of Maxwell’s classical electrodynamic equations.MCE falls into the QED(Quantum Electrodynamic)aspect of the Maxwell’s equations,in particular out of his four famous classical equations,our interest focuses on the one that is known to us as Faraday’s Law of the Maxwell’s Equation set.
基金supported in part by NSFC(Grant No.11375121,11747171,11747302 and 11847305)Natural Science Foundation of Chengdu University of TCM(Grants No.ZRYY1729 and ZRQN1656)+2 种基金Discipline Talent Promotion Program of Xinglin Scholars(Grant No.QNXZ2018050)The Key Fund Project for Education Department of Sichuan(Grant No.18ZA0173)Sichuan University Students Platform for Innovation and Entrepreneurship Training Program(Grant No.C2019104639).
文摘In this paper,we study the thermodynamics and the weak cosmic censorship conjecture of the nonlinear electrodynamics black hole under the scattering of a charged complex scalar field.According to the energy and charge fluxes of the scalar field,the variations of this black hole’s energy and charge can be calculated during an infinitesimal time interval.With scalar field scattering,the variation of the black hole is calculated in the extended and normal phase spaces.In the normal phase space,the cosmological constant and the normalization parameter are fixed,and the first and second laws of thermodynamics can also be satisfied.In the extended phase space,the cosmological constant and the normalization parameter are considered as thermodynamic variables,and the first law of thermodynamics is valid,but the second law of thermodynamics is not valid.Furthermore,the weak cosmic censorship conjecture is both valid in the extended and normal phase spaces.
基金Supported by the National Natural Science Foundation of China (No. 29876022) the Doctoral Foundation of Education Ministry of China (No. 20010610027).
文摘By introducing Oseen's formula to describe the viscous drag force, a more complete motion equation for a charged microparticle levitated in an electrodynamic balance (EDB) has been put forward and solved numerically by the classic Runge-Kutta method in this paper. The theoretical results have firstly demonstrated the existence of the particle oscillations and their characteristics, especially of the springpoint oscillation at large amplitude. And through the comparisons of theoretical and experimental trajectories, the adopted motion equation has proved to be able to rigorously describe the particle motion in non-Stokes region-the shape of trajectory and frequency characteristics are fairly consistent and the deviations of amplitude can usually be less than 10%.
基金supported by the Talent Research Fund of Hefei University(No.21-22RC09)National Natural Science Foundation of China(No.U22A20225)。
文摘In the design realm of fusion power supplies,structural components play a pivotal role in ensuring the safety of fusion devices.To verify the reliability of the converter structure design at the Comprehensive Research Facility for Fusion Technology(CRAFT),meticulous analysis of the converter's dynamic impact is carefully performed based on the worst fault current(400k A),firstly.Subsequently,the thermal stress analysis based on the maximum allowable steadystate temperature is finished,and the equivalent thermal stress,thermal deformation,maximum shear stress of a single bridge arm and the whole converter are studied.Furthermore,a simple research method involving the current-sharing characteristics of a bridge arm with multithyristor parallel connection is proposed using a combination of Simplorer with Q3D in ANSYS.The results show that the current-sharing characteristics are excellent.Finally,the structural design has been meticulously tailored to meet the established requirements.
文摘We calculate the scattering cross section of an electron with respect to the spontaneously produced laser radiation in the first free-electron laser （FEL） with quantum-wiggler electrodynamics （QWD）. The cross section is 1016 times the Thomson cross section, confirming the result obtained by a previous analysis of the experimental data. A QWD calculation show that spontaneous emission in an FEL using only an electric wiggler can be very strong while amplification through net stimulated emission is practically negligible.
文摘This theory aims beyond the possibilities being available from the Standard Model. Examples are given by the directly obtained rest masses of the elementary particles, the deduced values of the elementary charge and of the mass of the boson detected by CERN which are close to their experimental data, and by an incorporated spin of the photon.
