We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit （SO） coupling with the Lee-Low-Pines intermediate coupling method. O...We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit （SO） coupling with the Lee-Low-Pines intermediate coupling method. Our numerical results show that the Rashba SO interaction originating from the inversion asymmetry in the heterostructure splits the ground state energy of the polaron. The electron area/density and vector dependence of the ratio of the SO interaction to the total ground state energy or other energy composition are obvious. One can see that even without any external magnetic field, the ground state energy can be split by the Rashba SO interaction, and this split is not a single but a complex one. Since the presents of the phonons, whose energy gives negative contribution to the polaron＇s, the spin-splitting states of the polaron are more stable than electron＇s.展开更多
We revisit the harmonic approximation (HA) for a large Josephson junction interacting with some charge qubits through the variational approach for the quantum dynamics of the junction-qubit coupling system. By making ...We revisit the harmonic approximation (HA) for a large Josephson junction interacting with some charge qubits through the variational approach for the quantum dynamics of the junction-qubit coupling system. By making use of numerical calculation and analytical treatment, the conditions under which HA works well can be precisely presented to control the parameters implementing the two-qubit quantum logical gate through the couplings to the large junction with harmonic oscillator Hamiltonian.展开更多
An optimal trajectory planning method has been proposed for the walking locomotion of a biped mechanical system with thighs, shanks and small feet, which is modelled as a 3 DOF link system consisting of an inverted pe...An optimal trajectory planning method has been proposed for the walking locomotion of a biped mechanical system with thighs, shanks and small feet, which is modelled as a 3 DOF link system consisting of an inverted pendulum and a 2 DOF swing leg. The locomotion of swing and supporting legs is solved by the optimal trajectory planning based on function approximation. The optimal trajectory planning based on function approximation. The optimal walking locomotion solution with minimum square of input torque exhibits a natural walking gait with one step period of 0.64 s similar to the human walking gait by using the link parameters of an adult’s leg. It is concluded from the computation results that the method proposed in this paper has been proved to be an effective tool for solving the optimal walking locomotion and joint control torque problems for a 3 DOF biped mechanism; when the ankle joint of the supporting leg is a passive joint, a nearly, optimal walking solution can be obtained at t 1=0.49 s and t 2=10 s, and however, when the knee is a passive joint, it is impossible to obtain a solution which satisfies the constraint condition; for the link parameters used in this paper, the length of an optimal stride is 0.3 m.展开更多
基金The project supported by National Natural Science Foundation of China under Grant No. 10347004.
文摘We study theoretically the ground state energy of a polaron near the interface of a polar-polar semiconductor by considering the Rashba spin-orbit （SO） coupling with the Lee-Low-Pines intermediate coupling method. Our numerical results show that the Rashba SO interaction originating from the inversion asymmetry in the heterostructure splits the ground state energy of the polaron. The electron area/density and vector dependence of the ratio of the SO interaction to the total ground state energy or other energy composition are obvious. One can see that even without any external magnetic field, the ground state energy can be split by the Rashba SO interaction, and this split is not a single but a complex one. Since the presents of the phonons, whose energy gives negative contribution to the polaron＇s, the spin-splitting states of the polaron are more stable than electron＇s.
基金the Cooperation Foundation of Nankai University，Tianjin University for research of nanoscience，国家自然科学基金
文摘We revisit the harmonic approximation (HA) for a large Josephson junction interacting with some charge qubits through the variational approach for the quantum dynamics of the junction-qubit coupling system. By making use of numerical calculation and analytical treatment, the conditions under which HA works well can be precisely presented to control the parameters implementing the two-qubit quantum logical gate through the couplings to the large junction with harmonic oscillator Hamiltonian.
文摘An optimal trajectory planning method has been proposed for the walking locomotion of a biped mechanical system with thighs, shanks and small feet, which is modelled as a 3 DOF link system consisting of an inverted pendulum and a 2 DOF swing leg. The locomotion of swing and supporting legs is solved by the optimal trajectory planning based on function approximation. The optimal trajectory planning based on function approximation. The optimal walking locomotion solution with minimum square of input torque exhibits a natural walking gait with one step period of 0.64 s similar to the human walking gait by using the link parameters of an adult’s leg. It is concluded from the computation results that the method proposed in this paper has been proved to be an effective tool for solving the optimal walking locomotion and joint control torque problems for a 3 DOF biped mechanism; when the ankle joint of the supporting leg is a passive joint, a nearly, optimal walking solution can be obtained at t 1=0.49 s and t 2=10 s, and however, when the knee is a passive joint, it is impossible to obtain a solution which satisfies the constraint condition; for the link parameters used in this paper, the length of an optimal stride is 0.3 m.
