A family of rank-n （n = 5, 6, 7, 8） three-qubit mixed states are constructed. The explicit expressions for the three-tangle and optimal decompositions for all these states are given. The CKW relations for these stat...A family of rank-n （n = 5, 6, 7, 8） three-qubit mixed states are constructed. The explicit expressions for the three-tangle and optimal decompositions for all these states are given. The CKW relations for these states are also discussed.展开更多
To consummate the quantum pendulum theory whose Hamiltonian takes bosonic operator formalism and manifestly exhibits its dynamic behaviour in the entangled state representation, we introduce angular momentum state rep...To consummate the quantum pendulum theory whose Hamiltonian takes bosonic operator formalism and manifestly exhibits its dynamic behaviour in the entangled state representation, we introduce angular momentum state representation and phase state representation. It turns out that the angular momentum state is the partial wave expansion of the entangled state.展开更多
For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the...For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the system of Schrodinger representation in the Heisenberg representation. The wave function of the atoms is given. The stability factor determining the BEC and the selection rules of the quantum transition are solved.展开更多
The path-integral quantization of thermal scalar, vector, and spinor fields is performed newly in the coherent-state representation. In doing this, we choose the thermal electrodynamics and psi(4) theory as,examples. ...The path-integral quantization of thermal scalar, vector, and spinor fields is performed newly in the coherent-state representation. In doing this, we choose the thermal electrodynamics and psi(4) theory as,examples. By this quantization, correct expressions of the partition functions and the generating functionals for the quantum thermal electrodynamics and psi(4) theory are obtained in the coherent-state representation. These expressions allow us to perform analytical calculations of the partition functions and generating functionals and therefore are useful in practical applications. Especially, the perturbative expansions of the generating functionals are derived specifically by virtue of the stationary-phase method. The generating functionals formulated in the position space are re-derived from the ones given in the coherent-state representation.展开更多
Using the entangled state representation we present a formulation of Green'sfunction in solving Schrodinger equation for bipartite system with kinetic coupling.
The optical conductivity of impurity-doped parabolic quantum wells in anapplied electric field is investigated with the memory-function approach, and the analyticexpression for the optical conductivity is derived. Wit...The optical conductivity of impurity-doped parabolic quantum wells in anapplied electric field is investigated with the memory-function approach, and the analyticexpression for the optical conductivity is derived. With characteristic parameters pertaining toGaAs/Ga_(1-x)Al_xAs parabolic quantum wells, the numerical results are presented. It is shown that,the smaller the well width, the larger the peak intensity of the optical conductivity, and the moreasymmetric the shape of the optical conductivity; the optical conductivity is more sensitive to theelectric field, the electric Geld enhances the optical conductivity; when the dimension of thequantum well increases, the optical conductivity increases until it reaches a maximum value, andthen decreases.展开更多
We study the eigenstate problem of a kind of three coupled oscillators in anew quantum mechanical representation composed by the spontaneous eigenvectors 【 p,q_2,q_3| forthree operators (p_1 + p_2 + p_3), (x_3 - x_2)...We study the eigenstate problem of a kind of three coupled oscillators in anew quantum mechanical representation composed by the spontaneous eigenvectors 【 p,q_2,q_3| forthree operators (p_1 + p_2 + p_3), (x_3 - x_2), and (x_3 - x_1). The eigenvalues and eigenvectors ofthe Hamiltonian are obtained. With the same method, the eigenstate problem of a generalizedthree-coupled oscillator Hamiltonian is studied, which has never been studied before.展开更多
The four-particle EPR entangled state 【 p, X2,X3,X4 】 is constructed. Thecorresponding quantum mechanical operator with respect to the classical transformation p → e~(λ1)p, X2 → e~(λ2)X2, X3 → e~(λ3) X3, and ...The four-particle EPR entangled state 【 p, X2,X3,X4 】 is constructed. Thecorresponding quantum mechanical operator with respect to the classical transformation p → e~(λ1)p, X2 → e~(λ2)X2, X3 → e~(λ3) X3, and X4 → ee~(λ4) X4 in the state 【 p, X2, X3, X4 】 isinvestigated, and the four-mode realization of the S U(1, 1) Lie algebra as well as thecorresponding squeezing operators are presented.展开更多
In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-densi...In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-density matrix formalism.Here,we investigate the intersubband optical absorption coefficients and refractive index changes as a function of the triangle side(L) and the incident optical intensity(I).According to the obtained results,it is found that:(i) The total refractive index changes increase and shift towards lower energies when the triangle side increases.(ii) The total absorption coefficient decreases as the triangle side increases.Also,the resonance peak shifts towards lower energies by increasing the triangle side.展开更多
We demonstrate that the femtosecond time-resolved magneto-optical Kerr rotation oscillates with the direction of polarization of the probe beam when a sample of Al0.25Ga0.75As/GaAs multi-quantum wells is excited by a ...We demonstrate that the femtosecond time-resolved magneto-optical Kerr rotation oscillates with the direction of polarization of the probe beam when a sample of Al0.25Ga0.75As/GaAs multi-quantum wells is excited by a circularly polarized pump and detected by a linearly polarized probe at wavelengths from 800 to 830 nm. Analytical expressions are derived to explain the mechanism, which is in good agreement with the numerical computation and the experimental data. The results suggest that the Kerr signal can be enhanced by choosing an optimal direction of polarization, which is of benefit to the measurement of the weak Kerr rotation.展开更多
We provide a new expression of the quantum Fisher information(QFI) for a general system.Utilizing this expression,the QFI for a non-full rank density matrix is only determined by its support.This expression can bring ...We provide a new expression of the quantum Fisher information(QFI) for a general system.Utilizing this expression,the QFI for a non-full rank density matrix is only determined by its support.This expression can bring convenience for an infinite-dimensional density matrix with a finite support.Besides,a matrix representation of the QFI is also given.展开更多
The exactly solvable model of quasi-conical quantum dot, having a form of spherical sector, is proposed. Due to the specific symmetry of the problem the separation of variables in spherical coordinates is possible in ...The exactly solvable model of quasi-conical quantum dot, having a form of spherical sector, is proposed. Due to the specific symmetry of the problem the separation of variables in spherical coordinates is possible in the one- electron Sehrodinger equation. Analytical expressions for wave function and energy spectrum are obtained. It is shown that at small values of the stretch angle of spherical sector the problem is reduced to the conical QD problem. The comparison with previously performed works shows good agreement of results. As an application of the obtained results, the quantum transitions in the system are considered.展开更多
Quantum correlations in a family of states comprising any mixture of a pair of arbitrary bi-qubit product pure states are studied by employing geometric discord [Phys. Rev. Lett. 105(2010) 190502] as the quantifier. F...Quantum correlations in a family of states comprising any mixture of a pair of arbitrary bi-qubit product pure states are studied by employing geometric discord [Phys. Rev. Lett. 105(2010) 190502] as the quantifier. First, the inherent symmetry in the family of states about local unitary transformations is revealed. Then, the analytic expression of geometric discords in the states is worked out. Some concrete discussions and analyses on the captured geometric discords are made so that their distinct features are exposed. It is found that, the more averagely the two bi-qubit product states are mixed, the bigger geometric discord the mixed state owns. Moreover, the monotonic relationships of geometric discord with different parameters are revealed.展开更多
Quantum correlations among parts of a composite quantum system are a fundamental resource for several applications in quantum information. In general, quantum discord can measure quantum correlations. In that way,we i...Quantum correlations among parts of a composite quantum system are a fundamental resource for several applications in quantum information. In general, quantum discord can measure quantum correlations. In that way,we investigate the quantum discord of the two-qubit system constructed from the Yang–Baxter Equation. The density matrix of this system is generated through the unitary Yang–Baxter matrix R. The analytical expression and numerical result of quantum discord and geometric measure of quantum discord are obtained for the Yang–Baxter system. These results show that quantum discord and geometric measure of quantum discord are only connect with the parameter θ,which is the important spectral parameter in Yang–Baxter equation.展开更多
基金Supported by NSFC under Grant Nos.10871228,10875081,60873191,60903152,and 60821001SRFDP under Grant Nos.200800131016 and 20090005110010+2 种基金Beijing Nova Program under Grant No.2008B51Key Project of Chinese Ministry of Education under Grant No.109014Beijing Municipal Education Commission under Grant Nos.KM200510028021 and KZ200810028013
文摘A family of rank-n （n = 5, 6, 7, 8） three-qubit mixed states are constructed. The explicit expressions for the three-tangle and optimal decompositions for all these states are given. The CKW relations for these states are also discussed.
文摘To consummate the quantum pendulum theory whose Hamiltonian takes bosonic operator formalism and manifestly exhibits its dynamic behaviour in the entangled state representation, we introduce angular momentum state representation and phase state representation. It turns out that the angular momentum state is the partial wave expansion of the entangled state.
文摘For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the system of Schrodinger representation in the Heisenberg representation. The wave function of the atoms is given. The stability factor determining the BEC and the selection rules of the quantum transition are solved.
文摘The path-integral quantization of thermal scalar, vector, and spinor fields is performed newly in the coherent-state representation. In doing this, we choose the thermal electrodynamics and psi(4) theory as,examples. By this quantization, correct expressions of the partition functions and the generating functionals for the quantum thermal electrodynamics and psi(4) theory are obtained in the coherent-state representation. These expressions allow us to perform analytical calculations of the partition functions and generating functionals and therefore are useful in practical applications. Especially, the perturbative expansions of the generating functionals are derived specifically by virtue of the stationary-phase method. The generating functionals formulated in the position space are re-derived from the ones given in the coherent-state representation.
文摘Using the entangled state representation we present a formulation of Green'sfunction in solving Schrodinger equation for bipartite system with kinetic coupling.
文摘The optical conductivity of impurity-doped parabolic quantum wells in anapplied electric field is investigated with the memory-function approach, and the analyticexpression for the optical conductivity is derived. With characteristic parameters pertaining toGaAs/Ga_(1-x)Al_xAs parabolic quantum wells, the numerical results are presented. It is shown that,the smaller the well width, the larger the peak intensity of the optical conductivity, and the moreasymmetric the shape of the optical conductivity; the optical conductivity is more sensitive to theelectric field, the electric Geld enhances the optical conductivity; when the dimension of thequantum well increases, the optical conductivity increases until it reaches a maximum value, andthen decreases.
文摘We study the eigenstate problem of a kind of three coupled oscillators in anew quantum mechanical representation composed by the spontaneous eigenvectors 【 p,q_2,q_3| forthree operators (p_1 + p_2 + p_3), (x_3 - x_2), and (x_3 - x_1). The eigenvalues and eigenvectors ofthe Hamiltonian are obtained. With the same method, the eigenstate problem of a generalizedthree-coupled oscillator Hamiltonian is studied, which has never been studied before.
基金Open Foundation of Laboratory of High-intensity Optics，中国科学院资助项目
文摘The four-particle EPR entangled state 【 p, X2,X3,X4 】 is constructed. Thecorresponding quantum mechanical operator with respect to the classical transformation p → e~(λ1)p, X2 → e~(λ2)X2, X3 → e~(λ3) X3, and X4 → ee~(λ4) X4 in the state 【 p, X2, X3, X4 】 isinvestigated, and the four-mode realization of the S U(1, 1) Lie algebra as well as thecorresponding squeezing operators are presented.
文摘In the present work,the optical properties of a GaAs quantum wire with equilateral triangle cross section are studied.For this purpose,we use analytical expressions for optical properties obtained by the compact-density matrix formalism.Here,we investigate the intersubband optical absorption coefficients and refractive index changes as a function of the triangle side(L) and the incident optical intensity(I).According to the obtained results,it is found that:(i) The total refractive index changes increase and shift towards lower energies when the triangle side increases.(ii) The total absorption coefficient decreases as the triangle side increases.Also,the resonance peak shifts towards lower energies by increasing the triangle side.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10821062 and 11074013)
文摘We demonstrate that the femtosecond time-resolved magneto-optical Kerr rotation oscillates with the direction of polarization of the probe beam when a sample of Al0.25Ga0.75As/GaAs multi-quantum wells is excited by a circularly polarized pump and detected by a linearly polarized probe at wavelengths from 800 to 830 nm. Analytical expressions are derived to explain the mechanism, which is in good agreement with the numerical computation and the experimental data. The results suggest that the Kerr signal can be enhanced by choosing an optimal direction of polarization, which is of benefit to the measurement of the weak Kerr rotation.
基金Supported by the National Fundamental Research Program of China under Grant No.2012CB921602the National Natural Science Foundation of China under Grants Nos.11025527 and 10935010
文摘We provide a new expression of the quantum Fisher information(QFI) for a general system.Utilizing this expression,the QFI for a non-full rank density matrix is only determined by its support.This expression can bring convenience for an infinite-dimensional density matrix with a finite support.Besides,a matrix representation of the QFI is also given.
文摘The exactly solvable model of quasi-conical quantum dot, having a form of spherical sector, is proposed. Due to the specific symmetry of the problem the separation of variables in spherical coordinates is possible in the one- electron Sehrodinger equation. Analytical expressions for wave function and energy spectrum are obtained. It is shown that at small values of the stretch angle of spherical sector the problem is reduced to the conical QD problem. The comparison with previously performed works shows good agreement of results. As an application of the obtained results, the quantum transitions in the system are considered.
基金Supported by the National Natural Science Foundation of China(NNSFC)under Grant Nos.11375011 and 11372122the Natural Science Foundation of Anhui Province under Grant No.1408085MA12the 211 Project of Anhui University
文摘Quantum correlations in a family of states comprising any mixture of a pair of arbitrary bi-qubit product pure states are studied by employing geometric discord [Phys. Rev. Lett. 105(2010) 190502] as the quantifier. First, the inherent symmetry in the family of states about local unitary transformations is revealed. Then, the analytic expression of geometric discords in the states is worked out. Some concrete discussions and analyses on the captured geometric discords are made so that their distinct features are exposed. It is found that, the more averagely the two bi-qubit product states are mixed, the bigger geometric discord the mixed state owns. Moreover, the monotonic relationships of geometric discord with different parameters are revealed.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11247260 and 11305020 and the CUST Foundation for Young Scholars under Grant No. XQNJJ-2011-03
文摘Quantum correlations among parts of a composite quantum system are a fundamental resource for several applications in quantum information. In general, quantum discord can measure quantum correlations. In that way,we investigate the quantum discord of the two-qubit system constructed from the Yang–Baxter Equation. The density matrix of this system is generated through the unitary Yang–Baxter matrix R. The analytical expression and numerical result of quantum discord and geometric measure of quantum discord are obtained for the Yang–Baxter system. These results show that quantum discord and geometric measure of quantum discord are only connect with the parameter θ,which is the important spectral parameter in Yang–Baxter equation.
