Multiphoton spontaneous emission of an atom in a detuned damped cavity

The multiphoton spontaneous emission of a two-level atom in a detuned damped cavity is investigated. The exact expressions for the atomic population inversion and the radiation rate are obtained. The various characteristic times are calculated.     

Many-atom spontaneous emission in a lossless cavity

Applying a perturbation method, constructed in terms of SU(2)-group representations, we investigate the anharmonic dynamics of spontaneous emission of a system of N identical two-level atoms immersed in a single-mode ideal cavity with s atoms initially inverted. The phenomenon of collective collapses and revivals is revealed.     

Optomechanical dynamics in detuned whispering-gallery modes cavity

The dynamics of a microresonator in detuned whispering-gallery modes (WGM) cavity opto-mechanical system are investigated by the quantum Langevin equation. A WGM cavity coupling to two parallel waveguides is devised to study the transmission and reflection of this system. In single mode WGM cavity, without optomechanical coupling, both the transmission and reflection of the cavity present a Lorentzian dip and peak. When the coupling between the cavity mode and mechanical mode is considered, the transmission and reflection of the optomechanical cavity show “W” and “M” shape mode splitting. Moreover, under the action of a controlling and a probe laser, the output field at the probe frequency presents electromagnetically induced transparency (EIT)-like spectrum in the system. We give the physical origin of EIT-like and the pump-probe response for the WGM shares all the features of the Λ system in atoms. Further, due to backscattering, the two traveling waves in WGM are coupled with a rate γ. The transmission and reflection of the optomechanical cavity display three modes splitting in the spectra with optomechanical coupling between the two cavity modes and the mechanical mode.     

Preparation of cluster state in large detuned cavity

An experimentally realizable physical scheme for preparing multiqubit cluster states from a large detuned atomcavity interaction is proposed. The scheme is free of any type of measurement and insensitive to the cavity decay, and the cavity field is only virtually excited so that there is no information exchanging between atom and cavity. The time required for the gate operations is very short, which is important for decoherence. We also discuss the experimental feasibility of our scheme.     

Accelerating the spontaneous emission of x rays from atoms in a cavity

We have investigated the spontaneous radiative decay of resonant nuclei in a planar x-ray waveguide after excitation by synchrotron radiation pulses. The waveguide acts as a cavity and modifies the mode structure of the electromagnetic field. As a result, the rate of spontaneous emission is enhanced by a factor proportional to the density of photon states in the cavity. In this experiment, we have observed a sixfold acceleration of the coherent radiative decay of 57Fe nuclei located in the center of the first-order guided mode. This is in very good agreement with theoretical predictions.     

New approach to the exact theory of spontaneous emission in a cavity

Summary A version of the exact theory of the spontaneous emission of a motionless two-level atom in a cavity at zero temperature is presented. Using the analogy to radiative decay and a novel algorithm in solving the Schr?dinger equation, the theory predicts a hidden triplet form of the spectrum, which turns abruptly to a singlet with the cavity passive linewidth becoming equal to twice the coupling constant.     

Enhanced spontaneous emission into the mode of a cavity QED system

We study the light generated by spontaneous emission into a mode of a cavity QED system under weak excitation of the orthogonally polarized mode. Operating in the intermediate regime of cavity QED with comparable coherent and decoherent coupling constants, we find an enhancement of the emission into the undriven cavity mode by more than a factor of 18.5 over that expected by the solid angle subtended by the mode. A model that incorporates three atomic levels and two polarization modes quantitatively explains the observations.     

二能级原子与高品质因子腔的自发辐射特性

用全量子理论研究二能级原子单模腔耦合系统,通过理论推导和数值计算得出系统的自发辐射光谱和平均粒子数密度.共振时腔与原子的发射光谱在强耦合与弱耦合区域有所不同,腔发射光谱分裂只出现于强耦合区域,而原子发射光谱由于腔感应透明效应在弱耦合区域出现了缺口.本文系统地研究了原子与腔在失谐时的发射光谱,在好腔机理(腔线宽小于原子线宽g)原子与腔即使在大失谐时腔发射出腔频率的光子,这给当前实验上困惑的特性提供了一个理论依据.为了给腔感应透明效应一个新的深入了解,还研究了原子与腔平均粒子数密度随时间的演化,以及平均粒子数密度与光强度之间的关系. 关键词： 自发辐射 强耦合 腔感应透明 好腔机理     

Dynamics of the collective spontaneous emission of two three-level atoms in a cavity

Based on the master equation for the density matrix, the collective spontaneous emission of two A-type three-level atoms interacting with two modes of a quantum electromagnetic field in a finite-Q cavity is studied. The evolution of the emission intensity for each mode is found for the case where both atoms are initially in the excited state.     

Modification of spontaneous emission from a five-level M-type atom in coupled cavity waveguide

We study the spontaneous emission spectrum of a five-level M-type atom driven by a microwave field, in which two upper levels are coupled by the same-coupled cavity waveguide reservoir to a lower level. The spectrum behavior presents a strong non-Lorentzian shape that originates from effective quantum interference in Markovian reservoir, in which the spectral line can be significantly enhanced and eliminated by adjusting the proper parameters of the system. However, for non-Markovian reservoir, it seems that the shape of emission spectrum is quite dependent on the geometry behavior of a coupled cavity waveguide.     

Generation of photons in a lossy and detuned cavity with an oscillating boundary

A possibility of creating photons from vacuum due to the nonstationary Casimir effect in a weakly damped nondegenerate cavity with vibrating boundaries is analyzed in the case of a nonzero detuning from the exact resonance. It is shown that the photon generation is possible provided that the relative detuning and inverse quality factor do not exceed the critical value of the order of 10⁻⁸. Under this condition, the field goes finally to a highly squeezed quantum state.     

Lateral shift dependence of spontaneous emission in a planar cavity with perfect conducting cladding

We consider the effect of lateral shift of the “beams" resulting from the atom emissions on spontaneous decay of an excited atom embedded in a planar cavity with perfect conducting cladding. It is found that the spontaneous decay could be enhanced or suppressed owing to the positive and negative lateral shift at the interfaces of the cavity mirror. Compared with the emission between two perfect conducting plates, the surface guided modes could exist and for very thin planar cavity, the density of surface guided modes may be obviously larger than those of the propagating guided modes.     

Decay properties of a two-level atom in a non-resonant damped cavity

The upper state population evolution and the spontaneous emission spectrum of a two-level atom in a non-resonant damped cavity are investigated by using the resolvent operator. The analytic expressions of the spectrum and the upper state population with strong and intermediate coupling are obtained. The influence of coupling intensity and detuning on atomic spectrum is discussed. We find that the detuning affects strongly the shape of spectra.     

The influence of the counter-rotating terms on the single-atom spontaneous emission inside a low-Q cavity

Summary Taking into account the counter-rotating terms, an exact equation of motion for the atomic population inversion is derived in the case of the single-atom spontaneous emission inside a damped cavity, by applying a modified Robertson projection-operator method developed previously by the authors. For strongly damped (low-Q) cavities an analytic solution showing the significance of the effect of the counter-rotating terms is obtained. Experimental verification with Rydberg atoms may be feasible.     

Enhancement of spontaneous emission from the resonant modes of a photonic crystal slab single-defect cavity

Modification of the spontaneous-emission lifetime in photonic crystal single-defect resonant modes is studied with the finite-difference time domain method. We investigate spontaneous-emission enhancement from the monopole and the dipole modes of a hexagonal lattice cavity, considering the effects of the finite emitter linewidth and spectral detuning. Large spontaneous-emission enhancement of > 50 is achieved numerically from the high-quality-factor monopole mode when the emitter linewidth is comparable with the resonant-mode linewidth. However, if broad-linewidth material is used and a detuning effect is included, the dipole mode with a low quality factor and a smaller mode volume could be more advantageous for spontaneous-emission enhancement.     

Two-photon-pumped amplified spontaneous emission and cavity lasing of an organic dye HEASPS in PHEMA polymer

Two-photon-absorption (TPA)-induced upconverted amplified spontaneous emission (ASE) and cavity lasing of a styrylpyridinium dye: trans-4-[p-(N-hydroxyethyl-N-ethylamino)styryl]-N-methylpyridinium p-toluene sulfonate (abbreviated as HEASPS) in poly(2-hydroxyethyl methacrylate) (abbreviated as PHEMA) polymer were observed under a picosecond pump condition. The spectral and temporal behaviors of TPA-induced fluorescence, ASE and cavity lasing were studied. The cavity lasing with a total oscillation time of more than 200 ps was achieved when pumped with 1064-nm, 50-ps laser irradiation. The population inversion could persist for three times longer than the duration of the pump pulse. The gain coefficients of the dye-doped polymer at various wavelengths were calculated based on cavity lasing spectra and one-photon fluorescence spectra. PACS 78.20.Ek; 42.65.Ky; 42.65.Re; 78.47.+p