Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the co...Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.展开更多
In a simple hadronie model, the two-photon exchange contributions to the single spin asymmetries for the nucleon and the 3He are estimated. The results show that the elastic contributions of two-photon exchange to the...In a simple hadronie model, the two-photon exchange contributions to the single spin asymmetries for the nucleon and the 3He are estimated. The results show that the elastic contributions of two-photon exchange to the single spin asymmetries for the nucleon are rather small while those for the 3He are relatively large. Besides the strong angular dependence, the two-photon contributions to the single transfer. spin asymmetry for the 3He are very sensitive to the momentum展开更多
Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×...Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×→B）and→JII≡fd3x（∈0→E×→A⊥＋∈0Ei→τ× A⊥i）.Notably, at the classical level, →JI gives an exactly null result while →JI gives a finite value. This suggests that Jn leads to a simpler and more reasonable picture of the atomic spin, therefore qualifies as a more appropriate definition of the electromagnetic angular momentum. Our observation gives important hint on the delicate issue of gluon contribution to the nucleon spin.展开更多
By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-...By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.展开更多
Shape coexistence and band structure near yrast line of the Z ＝ N doubly magic nucleus 40Ca have been investigated by the configuration-dependent cranked Nilsson-Strutinsky approach. The observed normal deformed and ...Shape coexistence and band structure near yrast line of the Z ＝ N doubly magic nucleus 40Ca have been investigated by the configuration-dependent cranked Nilsson-Strutinsky approach. The observed normal deformed and superdeformed bands are explained and the terminating states are confirmed by the calculations. The transition quadrupole moment Qt of the calculated superdeformed band is in good agreement with the observed one at high spin. There is shape coexistence within the same configuration. Possible normal deformed and superdeformed bands with rotation around the intermediate axis in several interesting configurations of40Ca are discussed. Possible favored superdeformed band terminations in 38Ca and 38Ar are predicted. The experimental results in 38Ar are discussed simply.展开更多
The spin cut-off parameter of the nuclear level density and effective moment of inertia for a large number of nuclei have been determined from analysis of the experimental data on S-wave neutron resonances and spins o...The spin cut-off parameter of the nuclear level density and effective moment of inertia for a large number of nuclei have been determined from analysis of the experimental data on S-wave neutron resonances and spins of lowlying levels. Contrary to claims made before, it is shown the spin cut-off parameter differs considerably from their corresponding rigid body values, and the energy dependence of the effective moment of inertia confirms the interacting fermion model prediction.展开更多
核子(质子和中子的总称)大约占宇宙中可见物质总质量的99%.作为构成宇宙可见物质中的最主要成分,核子也是研究强相互作用,尤其是禁闭区非微扰QCD的重要实验室.电子离子对撞机(Electron Ion Collider, EIC),被称作当代卢瑟福散射实验,是...核子(质子和中子的总称)大约占宇宙中可见物质总质量的99%.作为构成宇宙可见物质中的最主要成分,核子也是研究强相互作用,尤其是禁闭区非微扰QCD的重要实验室.电子离子对撞机(Electron Ion Collider, EIC),被称作当代卢瑟福散射实验,是人类认识物质世界深层次结构,特别是核子与原子核结构的理想工具.中国极化电子离子对撞机项目设想在已开建的HIAF高能离子束的基础上升级建造中国电子-离子对撞机(EIC in China,EicC),为我国核物理与粒子物理以及相关科学领域提供大型综合实验平台.本文综述了EicC在核子内不同味道海夸克的一维自旋味道结构、横动量依赖部分子分布函数、广义部分子分布函数测量的理论和模拟研究,展示了EicC在以上测量中可达到的预期精度,以及与现有测量精度的对比.另外,本文也综述了EicC在质子质量起源、重味强子谱、核介质效应及π介子的内部结构等重要物理问题中的潜在贡献,以及EicC探测器概念设计.EicC装置将有力地促进人们对核子自旋和质量的起源、夸克胶子禁闭机制等基本问题的理解.展开更多
Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to r...Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to realize a general one-qubit gate. Based on two recent reports, we construct two Hamiltonians and experimentally realized nonadiabatic holonomic gates by a single-shot implementation in a two-qubit nuclear magnetic resonance （NMR） system. Two noncommuting one-qubit holonomic gates, rotating along .~ and ~ axes respectively, are implemented by evolving a work qubit and an ancillary qubit nonadiabatically following a quantum circuit designed. Using a sequence compiler developed for NMR quantum information processor, we optimize the whole pulse sequence, minimizing the total error of the implementation. Finally, all the nonadiabatic holonomic gates reach high unattenuated experimental fidelities over 98%.展开更多
We analytically investigate Multiple Quantum(MQ) NMR dynamics in a mixed-three-spin(1/2,1,1/2)system with XXX Heisenberg model at the front of an external homogeneous magnetic field B. A single-ion anisotropy property...We analytically investigate Multiple Quantum(MQ) NMR dynamics in a mixed-three-spin(1/2,1,1/2)system with XXX Heisenberg model at the front of an external homogeneous magnetic field B. A single-ion anisotropy property ζ is considered for the spin-1. The intensities dependence of MQ NMR coherences on their orders(zeroth and second orders) for two pairs of spins(1,1/2) and(1/2,1/2) of the favorite tripartite system are obtained. It is also investigated dynamics of the pairwise quantum entanglement for the bipartite(sub)systems(1,1/2) and(1/2,1/2)permanently coupled by, respectively, coupling constants J_1 and J_2, by means of concurrence and fidelity. Then, some straightforward comparisons are done between these quantities and the intensities of MQ NMR coherences and ultimately some interesting results are reported. We also show that the time evolution of MQ coherences based on the reduced density matrix of the pair spins(1,1/2) is closely connected with the dynamics of the pairwise entanglement. Finally, we prove that one can introduce MQ coherence of the zeroth order corresponds to the pair spins(1,1/2) as an entanglement witness at some special time intervals.展开更多
基金国家自然科学基金，Foundations of the Chinese Academy of Sciences (X-37)，the Chinese Ministry of Education (B-22)，中国科学院资助项目，the Chinese Academy of Sciences
文摘Based on a relativistic quark model approach with an effective potential , the spin content of the nucleon is investigated. Pseudo-scalar interaction between quarks and Goldstone bosons is employed to calculate the couplings between the Goldstone bosons and the nucleon. Different approaches to deal with the center of mass correction in the relativistic quark potential model approach are discussed.
文摘In a simple hadronie model, the two-photon exchange contributions to the single spin asymmetries for the nucleon and the 3He are estimated. The results show that the elastic contributions of two-photon exchange to the single spin asymmetries for the nucleon are rather small while those for the 3He are relatively large. Besides the strong angular dependence, the two-photon contributions to the single transfer. spin asymmetry for the 3He are very sensitive to the momentum
文摘Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×→B）and→JII≡fd3x（∈0→E×→A⊥＋∈0Ei→τ× A⊥i）.Notably, at the classical level, →JI gives an exactly null result while →JI gives a finite value. This suggests that Jn leads to a simpler and more reasonable picture of the atomic spin, therefore qualifies as a more appropriate definition of the electromagnetic angular momentum. Our observation gives important hint on the delicate issue of gluon contribution to the nucleon spin.
文摘By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.
文摘Shape coexistence and band structure near yrast line of the Z ＝ N doubly magic nucleus 40Ca have been investigated by the configuration-dependent cranked Nilsson-Strutinsky approach. The observed normal deformed and superdeformed bands are explained and the terminating states are confirmed by the calculations. The transition quadrupole moment Qt of the calculated superdeformed band is in good agreement with the observed one at high spin. There is shape coexistence within the same configuration. Possible normal deformed and superdeformed bands with rotation around the intermediate axis in several interesting configurations of40Ca are discussed. Possible favored superdeformed band terminations in 38Ca and 38Ar are predicted. The experimental results in 38Ar are discussed simply.
文摘The spin cut-off parameter of the nuclear level density and effective moment of inertia for a large number of nuclei have been determined from analysis of the experimental data on S-wave neutron resonances and spins of lowlying levels. Contrary to claims made before, it is shown the spin cut-off parameter differs considerably from their corresponding rigid body values, and the energy dependence of the effective moment of inertia confirms the interacting fermion model prediction.
文摘核子(质子和中子的总称)大约占宇宙中可见物质总质量的99%.作为构成宇宙可见物质中的最主要成分,核子也是研究强相互作用,尤其是禁闭区非微扰QCD的重要实验室.电子离子对撞机(Electron Ion Collider, EIC),被称作当代卢瑟福散射实验,是人类认识物质世界深层次结构,特别是核子与原子核结构的理想工具.中国极化电子离子对撞机项目设想在已开建的HIAF高能离子束的基础上升级建造中国电子-离子对撞机(EIC in China,EicC),为我国核物理与粒子物理以及相关科学领域提供大型综合实验平台.本文综述了EicC在核子内不同味道海夸克的一维自旋味道结构、横动量依赖部分子分布函数、广义部分子分布函数测量的理论和模拟研究,展示了EicC在以上测量中可达到的预期精度,以及与现有测量精度的对比.另外,本文也综述了EicC在质子质量起源、重味强子谱、核介质效应及π介子的内部结构等重要物理问题中的潜在贡献,以及EicC探测器概念设计.EicC装置将有力地促进人们对核子自旋和质量的起源、夸克胶子禁闭机制等基本问题的理解.
基金supported by the National Natural Science Foundation of China(Grant Nos.91221205,and 11474181)the National Basic Research Program of China(Grants No.2015CB921002)
文摘Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors. However, all the previous schemes have to use at least two sequentially implemented gates to realize a general one-qubit gate. Based on two recent reports, we construct two Hamiltonians and experimentally realized nonadiabatic holonomic gates by a single-shot implementation in a two-qubit nuclear magnetic resonance （NMR） system. Two noncommuting one-qubit holonomic gates, rotating along .~ and ~ axes respectively, are implemented by evolving a work qubit and an ancillary qubit nonadiabatically following a quantum circuit designed. Using a sequence compiler developed for NMR quantum information processor, we optimize the whole pulse sequence, minimizing the total error of the implementation. Finally, all the nonadiabatic holonomic gates reach high unattenuated experimental fidelities over 98%.
文摘We analytically investigate Multiple Quantum(MQ) NMR dynamics in a mixed-three-spin(1/2,1,1/2)system with XXX Heisenberg model at the front of an external homogeneous magnetic field B. A single-ion anisotropy property ζ is considered for the spin-1. The intensities dependence of MQ NMR coherences on their orders(zeroth and second orders) for two pairs of spins(1,1/2) and(1/2,1/2) of the favorite tripartite system are obtained. It is also investigated dynamics of the pairwise quantum entanglement for the bipartite(sub)systems(1,1/2) and(1/2,1/2)permanently coupled by, respectively, coupling constants J_1 and J_2, by means of concurrence and fidelity. Then, some straightforward comparisons are done between these quantities and the intensities of MQ NMR coherences and ultimately some interesting results are reported. We also show that the time evolution of MQ coherences based on the reduced density matrix of the pair spins(1,1/2) is closely connected with the dynamics of the pairwise entanglement. Finally, we prove that one can introduce MQ coherence of the zeroth order corresponds to the pair spins(1,1/2) as an entanglement witness at some special time intervals.
