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
In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate t...In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate the properties of fermions and bosons in 3D quantum electrodynamics QED and a series of self-consistent solutions for the fermion propagator in the Nambu and Wigner phases are obtained. These numerical solutions show that the propagator behaves very differently in the Landau gauge domain and in the infrared energy region outside it.By using the propagators in the Nambu and Wigner phases under various gauges it is further investigated how the fermion equivalent pressure difference and fermion condensation change with the gauge parameters.These results indicate that the phase transition described by the CJT equivalent potential and the chiral phase transition described by the chiral condensation are not completely identical.展开更多
Based on the study of the linear response of the fermion propagator to the presence of an external scalar field, a new method for calculating the staggered spin susceptibility in QED3 is presented, in which the influe...Based on the study of the linear response of the fermion propagator to the presence of an external scalar field, a new method for calculating the staggered spin susceptibility in QED3 is presented, in which the influence of the full vertex function is included. The numerical values of the staggered spin susceptibility are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach. A comparison between the result calculated using the full vertex and that using the bare vertex is given.展开更多
Adopting the approximation to the first order of chemical potential μ, we resolve rigidly the influence on fermion condensate from μ in QED3. We show that this condensate does not respond linear expression to μ. Mo...Adopting the approximation to the first order of chemical potential μ, we resolve rigidly the influence on fermion condensate from μ in QED3. We show that this condensate does not respond linear expression to μ. Moreover, the influence on fermion chiral condensate from chemieal potential is investigated.展开更多
Based on the external field approach and the differential form of Ward identity, we derive a more compact formula for the particle-number susceptibility in QED3 at finite temperature. Using the zero frequency approxim...Based on the external field approach and the differential form of Ward identity, we derive a more compact formula for the particle-number susceptibility in QED3 at finite temperature. Using the zero frequency approximation the numerical value of the particle-number susceptibility is calculated in the Dyson-Schwinger approach for the case that the number of fermion flavours equals one and two, respectively. An enhanced fluctuation of the particlenumber density is observed across the transition temperature, which should be an essential characteristic of chiral phase transition in QED3.展开更多
Since the massless quantum electrodynamics in 2+1 dimensions (QEDa) with nonzero gauge boson mass ζ can be used to explain some important traits of high-Tc superconductivity in planar cuprates, it is worthwhile to...Since the massless quantum electrodynamics in 2+1 dimensions (QEDa) with nonzero gauge boson mass ζ can be used to explain some important traits of high-Tc superconductivity in planar cuprates, it is worthwhile to apply this model to analyze the nature of chiral phase transition at the critical value ζ. Based on the feature of chiral susceptibility, we show that the system at ζ exhibits a second-order phase transition which accords with the nature of appearance of the high-To superconductivity, and the estimated critical exponents around ζ are illustrated.展开更多
In the case of nonzero fermion mass, within a range of Ansatze for the full fermion-boson vertex, we show that Dyson-Schwinger equation for the fermion propagator in QED3 has two qualitatively distinct dynamical chira...In the case of nonzero fermion mass, within a range of Ansatze for the full fermion-boson vertex, we show that Dyson-Schwinger equation for the fermion propagator in QED3 has two qualitatively distinct dynamical chiral symmetry breaking solutions. As the fermion mass increases and reaches to a critical value mc, one solution disappears, and the dependence of mc on the number of fermion flavors is also given.展开更多
The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagn...The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagnetic (LEM) waves. The revised Maxwell’s equations include the crucial parameters being the attenuation time constants of magnetic vortex potential and electric vortex potential generated by external electromagnetic field within the propagation medium. Specific expressions for them are obtained through theoretical analysis. Subsequently, a model for propagating magnetic P-wave generated by the superposition of a left-handed photo and a right-handed photon in a vacuum is formulated based on reevaluated total current law and revised Faraday’s law, covering wave equations, energy equation, as well as propagation mode involving mutual induction and conversion between scalar magnetic field and vortex electric field. Furthermore, through theoretical derivations centered around magnetic P-wave, evidence was presented regarding its ability to absorb huge free energy through the entangled interaction between zero-point vacuum energy field and the torsion field produced by the vortex electric field.展开更多
This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quant...This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.展开更多
An experimentally feasible protocol for realizing dense coding by using a class of W-state in cavity quantum electrodynamics (QED) is proposed in this paper. The prominent advantage of our scheme is that the success...An experimentally feasible protocol for realizing dense coding by using a class of W-state in cavity quantum electrodynamics (QED) is proposed in this paper. The prominent advantage of our scheme is that the successful probability of the dense coding with a W-class state can reach 1. In addition, the scheme can be implemented by the present cavity QED techniques.展开更多
An experimentally feasible scheme for implementing four-atom quantum dense coding of an atom-cavity system is proposed. The cavity is only virtually excited and no quantum information will be transferred from the atom...An experimentally feasible scheme for implementing four-atom quantum dense coding of an atom-cavity system is proposed. The cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity. Thus the scheme is insensitive to cavity decay and the thermal field. In the scheme, Alice can send faithfully 4 bits of classical information to Bob by sending two qubits. Generalized Bell states can be exactly distinguished by detecting the atomic state, and quantum dense coding can be realized in a simple way.展开更多
We propose schemes to realize robust quantum states transfer between distant resonators using the topological edge states of a one-dimensional circuit quantum electrodynamics(QED)lattice.Analyses show that the distrib...We propose schemes to realize robust quantum states transfer between distant resonators using the topological edge states of a one-dimensional circuit quantum electrodynamics(QED)lattice.Analyses show that the distribution of edge states can be regulated accordingly with the on-site defects added on the resonators.And we can achieve different types of quantum state transfer without adjusting the number of lattices.Numerical simulations demonstrate that the on-site defects can be used as a change-over switch for high-fidelity single-qubit and two-qubit quantum states transfer.This work provides a viable prospect for flexible quantum state transfer in solid-state topological quantum system.展开更多
High-dimensional quantum systems, such as qutrits(quantum three-level systems), have multiple accessible energy levels beyond the two-level qubits. Therefore, qutrits can offer a larger state space to improve the effi...High-dimensional quantum systems, such as qutrits(quantum three-level systems), have multiple accessible energy levels beyond the two-level qubits. Therefore, qutrits can offer a larger state space to improve the efficiency of quantum computation. Here, we demonstrate a high-fidelity iSWAP-like gate operation on a frequency-tunable superconducting qutrits system. The superconducting quantum system consists of two qutrits that are coupled via a resonator with fixed qutrit-resonator coupling strengths. Through designing the frequency pulse profile and optimizing the parameter values,the gate error can be suppressed below 1.5 × 10^(-3). To bear out the feasibility of the proposal, we have conducted our study with experimentally accessible parameters. As the resonator can mediate the interaction between the irrelevant qutrits, the presented approach can also be used to couple multiple qutrits together, providing a good platform for quantum information processing.展开更多
ZPE(zero-point energy)is a concept in physics that refers to the lowest possible energy state that a quantum mechanical physical system can have.It is the energy that remains even at absolute zero temperature,where al...ZPE(zero-point energy)is a concept in physics that refers to the lowest possible energy state that a quantum mechanical physical system can have.It is the energy that remains even at absolute zero temperature,where all classical forms of energy are assumed to be absent.Within quantum physics,the idea of ZPE is well-established.According to quantum field theory,quantum fields fluctuate even in empty space,resulting in a constant emergence and disappearance of particles and antiparticles.The ZPE comes from these fluctuations.ZPE can be used as a useful energy source;however,this idea is still up for discussion.ZPE has occasionally been linked in popular culture to pseudoscientific claims about“free energy”and perpetual motion machines.These assertions are usually unfounded and go beyond what is currently known about ZPE.There are currently no practical applications or tools that can extract useful energy from ZPE,even though it has fascinating theoretical implications and has been researched in the context of quantum field theory.Within the confines of currently understood physics,researchers are still exploring the concept’s potential ramifications and uses.展开更多
The discovery of scalar energy many years ago has mostly been ignored since then.Scalar energy is still misunderstood,underappreciated,and underutilized today.To comprehend the future,one must look back at the past.Sc...The discovery of scalar energy many years ago has mostly been ignored since then.Scalar energy is still misunderstood,underappreciated,and underutilized today.To comprehend the future,one must look back at the past.Scalar energy was first discovered by Scottish physicist James Clark Maxwell,who was born in 1831.Maxwell made significant advances in mathematical physics.He developed the theories relating to electromagnetic fields and radiation.Maxwell’s discoveries were advanced by Nikola Tesla,who also created instruments that demonstrated the presence of scalar energy.Nicola Tesla discovered an electromagnetic longitudinal wave in the early 1900s.It is capable of lossless energy transmission over great distances,lossless power transmission through solid metal objects,and wireless energy transmission.In this patent,Tesla neither named it nor provided a description of how it operated.Now,in the twenty-first century,it is referred to as LSWs(longitudinal scalar waves).Instantaneous longitudinal waves called scalars cover the entire field.In contrast to electromagnetic waves,which are transverse and move along an axis in a certain direction,they do not propagate along an axis or have a direction.As“vector”waves,electromagnetic waves lose power as they travel farther and pass through solid metal objects.Scalar waves also offer a unique property that Tesla does not include in his patent,which concentrates on the transportation of energy.These waves can transmit information as well.展开更多
Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger(D-S) equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies...Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger(D-S) equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.展开更多
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The National Natural Science Foundation of China(No.10947127)the Science Foundation of Southeast University(No.11047005)
文摘In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate the properties of fermions and bosons in 3D quantum electrodynamics QED and a series of self-consistent solutions for the fermion propagator in the Nambu and Wigner phases are obtained. These numerical solutions show that the propagator behaves very differently in the Landau gauge domain and in the infrared energy region outside it.By using the propagators in the Nambu and Wigner phases under various gauges it is further investigated how the fermion equivalent pressure difference and fermion condensation change with the gauge parameters.These results indicate that the phase transition described by the CJT equivalent potential and the chiral phase transition described by the chiral condensation are not completely identical.
基金supported by National Natural Science Foundation of China under Grant No.10575050the Research Fund for the Doctoral Program of Higher Education under Grant No.20060284020
文摘Based on the study of the linear response of the fermion propagator to the presence of an external scalar field, a new method for calculating the staggered spin susceptibility in QED3 is presented, in which the influence of the full vertex function is included. The numerical values of the staggered spin susceptibility are calculated within the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach. A comparison between the result calculated using the full vertex and that using the bare vertex is given.
基金Supported in Part by the Science Foundation of Southeast UniversityChina Postdoctoral Science Foundation Funded Project under Grant No.20070420192
文摘Adopting the approximation to the first order of chemical potential μ, we resolve rigidly the influence on fermion condensate from μ in QED3. We show that this condensate does not respond linear expression to μ. Moreover, the influence on fermion chiral condensate from chemieal potential is investigated.
基金Supported in part by the National Natural Science Foundation of China under Grant Nos 10575050 and 10775069, and the Research Fund for the Doctoral Programme of Higher Education under Grant No 20060284020.
文摘Based on the external field approach and the differential form of Ward identity, we derive a more compact formula for the particle-number susceptibility in QED3 at finite temperature. Using the zero frequency approximation the numerical value of the particle-number susceptibility is calculated in the Dyson-Schwinger approach for the case that the number of fermion flavours equals one and two, respectively. An enhanced fluctuation of the particlenumber density is observed across the transition temperature, which should be an essential characteristic of chiral phase transition in QED3.
基金Supported by the Natural Science Foundation of Jiangsu Province under Grant No BK20130387the Fundamental Research Funds for the Central Universities under Grant No 2242014R30011
文摘Since the massless quantum electrodynamics in 2+1 dimensions (QEDa) with nonzero gauge boson mass ζ can be used to explain some important traits of high-Tc superconductivity in planar cuprates, it is worthwhile to apply this model to analyze the nature of chiral phase transition at the critical value ζ. Based on the feature of chiral susceptibility, we show that the system at ζ exhibits a second-order phase transition which accords with the nature of appearance of the high-To superconductivity, and the estimated critical exponents around ζ are illustrated.
文摘In the case of nonzero fermion mass, within a range of Ansatze for the full fermion-boson vertex, we show that Dyson-Schwinger equation for the fermion propagator in QED3 has two qualitatively distinct dynamical chiral symmetry breaking solutions. As the fermion mass increases and reaches to a critical value mc, one solution disappears, and the dependence of mc on the number of fermion flavors is also given.
文摘The longitudinal wave term within Faraday’s law of electromagnetic induction (Faraday’s law) underwent recovery to ensure its suitability for theoretical derivation of the equation governing longitudinal electromagnetic (LEM) waves. The revised Maxwell’s equations include the crucial parameters being the attenuation time constants of magnetic vortex potential and electric vortex potential generated by external electromagnetic field within the propagation medium. Specific expressions for them are obtained through theoretical analysis. Subsequently, a model for propagating magnetic P-wave generated by the superposition of a left-handed photo and a right-handed photon in a vacuum is formulated based on reevaluated total current law and revised Faraday’s law, covering wave equations, energy equation, as well as propagation mode involving mutual induction and conversion between scalar magnetic field and vortex electric field. Furthermore, through theoretical derivations centered around magnetic P-wave, evidence was presented regarding its ability to absorb huge free energy through the entangled interaction between zero-point vacuum energy field and the torsion field produced by the vortex electric field.
基金Project supported by the Postdoctal Foundation of Central South University of Chinathe Important Program of Hunan Provincial Education Department of China (Grant No. 06A038)+1 种基金Department of Education of Hunan Province of China (Grant No. 06C080)Hunan Provincial Natural Science Foundation,China (Grant No. 07JJ3013)
文摘This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.
基金supported by the National Natural Science Foundation of China (Grant No 10674001)the Program of Education Department of Anhui University of China (Grant No KJ2007A002)the Youth Program of Fuyang Normal College of China (Grant No 2005LQ04)
文摘An experimentally feasible protocol for realizing dense coding by using a class of W-state in cavity quantum electrodynamics (QED) is proposed in this paper. The prominent advantage of our scheme is that the successful probability of the dense coding with a W-class state can reach 1. In addition, the scheme can be implemented by the present cavity QED techniques.
基金Project supported by the Postdoctal Foundation of Central South University of China, the Important Program of Hunan Provincial Education Department (Grant No. 06A038)Department of Education of Hunan Province of China (Grant No. 06C080)Hunan Provincial Natural Science Foundation, China (Grant No. 07JJ3013)
文摘An experimentally feasible scheme for implementing four-atom quantum dense coding of an atom-cavity system is proposed. The cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity. Thus the scheme is insensitive to cavity decay and the thermal field. In the scheme, Alice can send faithfully 4 bits of classical information to Bob by sending two qubits. Generalized Bell states can be exactly distinguished by detecting the atomic state, and quantum dense coding can be realized in a simple way.
基金supported by the National Natural Science Foundation of China(Grant Nos.61801280,61805134,and 61822114)the Applied Fundamental Research Projects of Shanxi Province,China(Grant No.201801D221015)Science and Technology Innovation Project of Shanxi Normal University(Grant No.2020XSY032)。
文摘We propose schemes to realize robust quantum states transfer between distant resonators using the topological edge states of a one-dimensional circuit quantum electrodynamics(QED)lattice.Analyses show that the distribution of edge states can be regulated accordingly with the on-site defects added on the resonators.And we can achieve different types of quantum state transfer without adjusting the number of lattices.Numerical simulations demonstrate that the on-site defects can be used as a change-over switch for high-fidelity single-qubit and two-qubit quantum states transfer.This work provides a viable prospect for flexible quantum state transfer in solid-state topological quantum system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12105146 and 12175104)supported by the National Natural Science Foundation of China (Grant No. 61871234)sponsored by NUPTSF (Grant No. NY220178)。
文摘High-dimensional quantum systems, such as qutrits(quantum three-level systems), have multiple accessible energy levels beyond the two-level qubits. Therefore, qutrits can offer a larger state space to improve the efficiency of quantum computation. Here, we demonstrate a high-fidelity iSWAP-like gate operation on a frequency-tunable superconducting qutrits system. The superconducting quantum system consists of two qutrits that are coupled via a resonator with fixed qutrit-resonator coupling strengths. Through designing the frequency pulse profile and optimizing the parameter values,the gate error can be suppressed below 1.5 × 10^(-3). To bear out the feasibility of the proposal, we have conducted our study with experimentally accessible parameters. As the resonator can mediate the interaction between the irrelevant qutrits, the presented approach can also be used to couple multiple qutrits together, providing a good platform for quantum information processing.
文摘ZPE(zero-point energy)is a concept in physics that refers to the lowest possible energy state that a quantum mechanical physical system can have.It is the energy that remains even at absolute zero temperature,where all classical forms of energy are assumed to be absent.Within quantum physics,the idea of ZPE is well-established.According to quantum field theory,quantum fields fluctuate even in empty space,resulting in a constant emergence and disappearance of particles and antiparticles.The ZPE comes from these fluctuations.ZPE can be used as a useful energy source;however,this idea is still up for discussion.ZPE has occasionally been linked in popular culture to pseudoscientific claims about“free energy”and perpetual motion machines.These assertions are usually unfounded and go beyond what is currently known about ZPE.There are currently no practical applications or tools that can extract useful energy from ZPE,even though it has fascinating theoretical implications and has been researched in the context of quantum field theory.Within the confines of currently understood physics,researchers are still exploring the concept’s potential ramifications and uses.
文摘The discovery of scalar energy many years ago has mostly been ignored since then.Scalar energy is still misunderstood,underappreciated,and underutilized today.To comprehend the future,one must look back at the past.Scalar energy was first discovered by Scottish physicist James Clark Maxwell,who was born in 1831.Maxwell made significant advances in mathematical physics.He developed the theories relating to electromagnetic fields and radiation.Maxwell’s discoveries were advanced by Nikola Tesla,who also created instruments that demonstrated the presence of scalar energy.Nicola Tesla discovered an electromagnetic longitudinal wave in the early 1900s.It is capable of lossless energy transmission over great distances,lossless power transmission through solid metal objects,and wireless energy transmission.In this patent,Tesla neither named it nor provided a description of how it operated.Now,in the twenty-first century,it is referred to as LSWs(longitudinal scalar waves).Instantaneous longitudinal waves called scalars cover the entire field.In contrast to electromagnetic waves,which are transverse and move along an axis in a certain direction,they do not propagate along an axis or have a direction.As“vector”waves,electromagnetic waves lose power as they travel farther and pass through solid metal objects.Scalar waves also offer a unique property that Tesla does not include in his patent,which concentrates on the transportation of energy.These waves can transmit information as well.
基金The Science Foundation of Southeast University,the National Natural Science Foundation of China (No. 11047005)
文摘Based on three-dimensional quantum electrodynamics theory,a set of truncated Dyson-Schwinger(D-S) equations are solved to study photon and fermion propagators with the effect of vacuum polarization.Numerical studies show that condensation and the value of fermion mass depends heavily on how the D-S equations are truncated.By solving a set of coupled D-S equations,it is also found that the fermion propagator shows a clear dependence on the order parameter.The truncated D-S equations under unquenched approximation are used to study the mass-function and chiral condensation of the fermions.The results under the unquenched approximation are clearly different from the ones under quenched approximation.With the increase in the order parameter,the fermion condensation in the unquenched approximation decreases when 0≤ξ5,while it increases when ξ5.However,nothing like this is observed in the quenched approximation,which indicates that there may be flaws in the quenched approximations.