We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependen...We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependent on the phase of atomic radiation and the speeding up of collective decay can only be observed in a bad cavity regime. For in-or out-phase case,this occurs due to the quantum interference enhancement, no matter which atom is excited initially. For π/2 phase, the speeding up of collective decay takes place if the first atom is excited at the beginning. However, it disappears due to the quantum interference cancellation if the second atom is excited. Compared with the in-phase and out-phase cases,we also show that the speeding up of collective decay can be significantly enhanced in strong coupling regime for π/2 phase, although one atom is decoupled to the cavity in this condition. The study presented here is helpful to understand the physical mechanism of collective decay in cavity quantum electrodynamics and it provides a useful method to control the collective decay phenomenon via quantum interference effect.展开更多
We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerat...We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerated and degenerated. By applying the hard-wall boundary condition of the semi-infinite waveguide, it is found that singlephoton polarization conversion can be realized with unit probability for both cases under the ideal condition.Together with the polarization conversion, the frequency conversion of a single photon can also be realized with unit probability in the ideal case if the Λ system is not degenerated.展开更多
We investigate theoretically single photon transport in one-dimensional waveguide coupled to a pair of cavities,which are denoted by the first cavity and the auxiliary cavity.Two cases with no atom and one atom embedd...We investigate theoretically single photon transport in one-dimensional waveguide coupled to a pair of cavities,which are denoted by the first cavity and the auxiliary cavity.Two cases with no atom and one atom embedded in the first cavity are discussed.The Fano dips in the transmission spectrum and locations of transparency window are calculated.When no atom is embedded in the first cavity,there exists a transparency window under the condition that the first cavity and the auxiliary cavity are not resonant.The locations of the transparency window and Fano line type depend strongly on the eigen frequency of the auxiliary cavity and the coupling strength between the auxiliary cavity and the waveguide.When one atom is embedded in the first cavity,we show that the transparency window exists even though the first cavity,the atom and the auxiliary cavity are resonant.The Fano line type is strongly dependent on the eigen frequency of the auxiliary cavity and the coupling strength.Our results have potential applications in design of quantum devices at the level of single photon,such as single photon switch and single photon routers.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504272,11774262,11474003,and 11504003)the National Key Basic Research Special Foundation(Grant No.2016YFA0302800)+2 种基金the Joint Fund of the National Natural Science Foundation of China(Grant No.U1330203)the Fund from the Shanghai Science and Technology Committee(STCSM)(Grant No.18JC1410900)the Natural Science Foundation of Anhui Province,China(Grant Nos.1408085MA19 and 1608085ME102)
文摘We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependent on the phase of atomic radiation and the speeding up of collective decay can only be observed in a bad cavity regime. For in-or out-phase case,this occurs due to the quantum interference enhancement, no matter which atom is excited initially. For π/2 phase, the speeding up of collective decay takes place if the first atom is excited at the beginning. However, it disappears due to the quantum interference cancellation if the second atom is excited. Compared with the in-phase and out-phase cases,we also show that the speeding up of collective decay can be significantly enhanced in strong coupling regime for π/2 phase, although one atom is decoupled to the cavity in this condition. The study presented here is helpful to understand the physical mechanism of collective decay in cavity quantum electrodynamics and it provides a useful method to control the collective decay phenomenon via quantum interference effect.
基金Supported by the Anhui Provincial Natural Science Foundation under Grant Nos 1608085MA05 and 1608085MA09the National Natural Science Foundation of China under Grant Nos 11774262 and 11474003
文摘We theoretically investigate single-photon polarization conversion via scattering by an atom with Λ configuration coupled to a semi-infinite waveguide and discuss the two cases in which the Λ system is non-degenerated and degenerated. By applying the hard-wall boundary condition of the semi-infinite waveguide, it is found that singlephoton polarization conversion can be realized with unit probability for both cases under the ideal condition.Together with the polarization conversion, the frequency conversion of a single photon can also be realized with unit probability in the ideal case if the Λ system is not degenerated.
基金supported by the National Natural Science Foundation of China(Grant Nos.11774262 and 11975023)。
文摘We investigate theoretically single photon transport in one-dimensional waveguide coupled to a pair of cavities,which are denoted by the first cavity and the auxiliary cavity.Two cases with no atom and one atom embedded in the first cavity are discussed.The Fano dips in the transmission spectrum and locations of transparency window are calculated.When no atom is embedded in the first cavity,there exists a transparency window under the condition that the first cavity and the auxiliary cavity are not resonant.The locations of the transparency window and Fano line type depend strongly on the eigen frequency of the auxiliary cavity and the coupling strength between the auxiliary cavity and the waveguide.When one atom is embedded in the first cavity,we show that the transparency window exists even though the first cavity,the atom and the auxiliary cavity are resonant.The Fano line type is strongly dependent on the eigen frequency of the auxiliary cavity and the coupling strength.Our results have potential applications in design of quantum devices at the level of single photon,such as single photon switch and single photon routers.
