The effects of exciton-optical phonon interaction on the binding energy and the total and reduced effective masses of an exciton in a cylindrical quantum wire have been investigated. We adopt a perturbative-PLL [T.D. ...The effects of exciton-optical phonon interaction on the binding energy and the total and reduced effective masses of an exciton in a cylindrical quantum wire have been investigated. We adopt a perturbative-PLL [T.D. Lee,F. Low, and D. Pines, Phys. Rev. B90 (1953) 297] technique to construct an effective Hamiltonian and then use a variational solution to deal with the exciton-phonon system. The interactions of exciton with the longitudinal-optical phonon and the surface-optical phonon have been taken into consideration. The numerical calculations for GaAs show that the influences of phonon modes on the exciton in a quasi-one-dimensional quantum wire are considerable and should not be neglected. Moreover the numerical results for heavy- and light-hole exciton are obtained, which show that the polaronic effects on two types of excitons are very different but both depend heavily on the sizes of the wire.展开更多
We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effec...We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.展开更多
Pr3+and Yb3+co-doped phosphate glasses are prepared to study their optical properties.Excitation and emission spectra and decay curves are used to characterize their luminescence.We demonstrate that upon excitation of...Pr3+and Yb3+co-doped phosphate glasses are prepared to study their optical properties.Excitation and emission spectra and decay curves are used to characterize their luminescence.We demonstrate that upon excitation of Pr3+ion with one high energy photon at 470 nm,two near-infrared(NIR)photons are emitted at 950-1100 nm(Yb3+:2F 5/2 →2F 7/2)through an efficient cooperative energy transfer(CET)from Pr3+to Yb3+.The maximum energy transfer efficiency(ETE)and the corresponding quantum efficiency approach up to 90.17%and 190.17%,respectively.The glass materials might find potential application for improving the efficiency of silicon-based solar cells.展开更多
In this work,we study environment-assisted excitation energy transfer(EET) through calculating energy transfer efficiency(ETE) in LH1-RC-type and LH2-type trimers,which can be used to mimic energy transfer behaviors i...In this work,we study environment-assisted excitation energy transfer(EET) through calculating energy transfer efficiency(ETE) in LH1-RC-type and LH2-type trimers,which can be used to mimic energy transfer behaviors in the basic unit cells of LH1-RC and LH2 light-harvesting complexes.Quantum state evolution of the trimers is described by a non-Hermitian quantum master equation.ETE in these trimer systems is investigated by the use of numerical solutions at finite temperatures for the non-Hermitian master equation.We theoretically reveal the temperature-assisted ETE enhancement.It is found that highly efficient EET with nearly unit efficiency may occur in the nearby regime of the critical point of quantum phase transition.展开更多
文摘The effects of exciton-optical phonon interaction on the binding energy and the total and reduced effective masses of an exciton in a cylindrical quantum wire have been investigated. We adopt a perturbative-PLL [T.D. Lee,F. Low, and D. Pines, Phys. Rev. B90 (1953) 297] technique to construct an effective Hamiltonian and then use a variational solution to deal with the exciton-phonon system. The interactions of exciton with the longitudinal-optical phonon and the surface-optical phonon have been taken into consideration. The numerical calculations for GaAs show that the influences of phonon modes on the exciton in a quasi-one-dimensional quantum wire are considerable and should not be neglected. Moreover the numerical results for heavy- and light-hole exciton are obtained, which show that the polaronic effects on two types of excitons are very different but both depend heavily on the sizes of the wire.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10174066 and 10275055
文摘We adopt a dynamical algebraic method to study a four-level excited-doublet atom model and obtain the explicit expressions of the time-evolution operator and the density operator for the system. The nonclassical effects of the system, such as collapses and revivals of the atomic inversion and squeezing of the radiation field, are also discussed.
基金supported by the National Natural Science Foundation of China(Nos.61275180,51272109and50972061)the Natural Science Foundation of Zhejiang Province(Nos.Z4110072and R4100364)+1 种基金the Opening Foundation of Zhejiang Provincial Top Key DisciplineK.C.Wong Magna Fund in Ningbo University
文摘Pr3+and Yb3+co-doped phosphate glasses are prepared to study their optical properties.Excitation and emission spectra and decay curves are used to characterize their luminescence.We demonstrate that upon excitation of Pr3+ion with one high energy photon at 470 nm,two near-infrared(NIR)photons are emitted at 950-1100 nm(Yb3+:2F 5/2 →2F 7/2)through an efficient cooperative energy transfer(CET)from Pr3+to Yb3+.The maximum energy transfer efficiency(ETE)and the corresponding quantum efficiency approach up to 90.17%and 190.17%,respectively.The glass materials might find potential application for improving the efficiency of silicon-based solar cells.
基金supported by the National Fundamental Research Program (Grant No. 2007CB925204)the National Natural Science Foundation of China (Grant Nos. 11075050 and 10775048)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University (Grant No. IRT0964)the Hunan Provincial Natural Science Foundation (Grant No. 11JJ7001)
文摘In this work,we study environment-assisted excitation energy transfer(EET) through calculating energy transfer efficiency(ETE) in LH1-RC-type and LH2-type trimers,which can be used to mimic energy transfer behaviors in the basic unit cells of LH1-RC and LH2 light-harvesting complexes.Quantum state evolution of the trimers is described by a non-Hermitian quantum master equation.ETE in these trimer systems is investigated by the use of numerical solutions at finite temperatures for the non-Hermitian master equation.We theoretically reveal the temperature-assisted ETE enhancement.It is found that highly efficient EET with nearly unit efficiency may occur in the nearby regime of the critical point of quantum phase transition.
