The standard theory of resonance fluorescence is a weak-coupling theory.1 If n ¯ is the mean photon number for the driving field, g is the atom field coupling constant, and γ is the Einstein A coefficient, formally the standard theory of resonance fluorescence assumes the limit n ¯ → ∞ , g/ γ → 0, with the ratio of Rabi frequency to atomic linewidth 2 n ¯ n g / γ finite. The limit g/γ → 0 allows the variation of the Rabi frequency 2 n g across the photon number distribution of the driving field to be neglected. By placing the atom inside an optical cavity the ratio g/γ can be changed. In this paper we calculate spectra for intracavity resonance fluorescence in the strong-coupling limit g/γ ≫ 1, g/κ ≫ 1, where κ is the cavity linewidth. We consider a single two-level atom interacting on resonance with a single cavity mode driven by a resonant coherent field. The cavity subtends a small solid angle at the atom, so that the spontaneous emission into free-space modes is not negligible. We calculate the spectrum of the light transmitted by the cavity (the transmitted spectrum) and the spectrum of the light radiated by the atom into free space (the fluorescent spectrum). The transmitted and fluorescent spectra show fundamental differences from the (weak-coupling) spectrum of free-space resonance fluorescence.
The standard theory of resonance fluorescence is a weak-coupling theory.1 If n ¯ is the mean photon number for the driving field, g is the atom field coupling constant, and γ is the Einstein A coefficient, formally the standard theory of resonance fluorescence assumes the limit n ¯ → ∞ , g/ γ → 0, with the ratio of Rabi frequency to atomic linewidth 2 n ¯ n g / γ finite. The limit g/γ → 0 allows the variation of the Rabi frequency 2 n g across the photon number distribution of the driving field to be neglected. By placing the atom inside an optical cavity the ratio g/γ can be changed. In this paper we calculate spectra for intracavity resonance fluorescence in the strong-coupling limit g/γ ≫ 1, g/κ ≫ 1, where κ is the cavity linewidth. We consider a single two-level atom interacting on resonance with a single cavity mode driven by a resonant coherent field. The cavity subtends a small solid angle at the atom, so that the spontaneous emission into free-space modes is not negligible. We calculate the spectrum of the light transmitted by the cavity (the transmitted spectrum) and the spectrum of the light radiated by the atom into free space (the fluorescent spectrum). The transmitted and fluorescent spectra show fundamental differences from the (weak-coupling) spectrum of free-space resonance fluorescence.
There is increasing interest in the photon statistics and spectroscopic properties of the radiation from atoms confined in an optical cavity. Effects such as the cavity enhancement and inhibition of spontaneous emission, which were first observed using microwave cavities, have recently been measured at optical frequencies.1 Recent measurements of squeezing and the dynamic effects of single-quantum-level splittings also demonstrate the possibilities for quantum-statistical studies of coupled atom-cavity systems at optical frequencies.2 We study a single two-level atom confined inside an optical cavity which is driven by coherent light in resonance with both cavity and atom. For weak driving field intensities we have calculated the spectrum of the light transmitted by the cavity and fluorescence out the sides of the cavity.
We calculate the steady-state spectrum of resonance fluorescence from a two-level atom coupled to a single cavity mode and driven by a strong, in general off-resonance, external field. In the strong-coupling limit, each Mollow triplet component is split into a multiplet, whose detailed structure depends on the atom–cavity coupling, the cavity and spontaneous emission decay constants, and the photon-number distribution of the cavity mode. The dressed states for this system are identified, and the spectral features are interpreted in terms of transitions among these dressed states. In particular, we find that the central component of the central multiplet can have a strongly subnatural linewidth.
The spectrum of the resonance fluorescence light from a single two-level atom in a small, high-quality, optical cavity is calculated. The coupling between the atom and cavity is made sufficiently strong compared to the dissipation that single quantum frequency splitting (vacuum Rabi splitting) occurs. Under high excitation qualitatively new fluorescent spectra are predicted. The usual three-peaked resonance fluorescence spectrum now has sidebands whose width is given by the Jaynes-Cummings atom-cavity coupling coefficient rather than by the system dissipation.
We study a single two-level atom interacting on resonance with a weakly driven optical cavity mode. In earlier work on this system we calculated the degree of second-order coherence, the optical spectrum, and the spectrum of squeezing for both the transmitted light and fluorescence out the sides of the cavity.1,2 We present results for the cross-correlation functions that determine joint probabilities for a photodetection in transmission (fluorescence) followed by a photodetection in fluorescence (transmission). We compute these correlation functions numerically for arbitrary values of the three rates that govern the system dynamics: the atomic decay rate γ to modes other than the cavity mode, the photon escape rate from the cavity 2K, and the atom-field coupling constant g. Analytical results provide insight for the following limits of the parameters: (1) the bad-cavity limit, κ/γ→∞,κ/g→∞,g2/κγ constant; (2) the atomic-loss limit, κ/γ→0,κ/g→0,γ/g constant; (3) the cavity-loss limit, γ/κ→0,γ/g→0,g/κ constant; and (4) the good-cavity limit, k/γ→0,k/g→0,g2/κγ constant. In the bad-cavity limit the cross-correlation functions are symmetric with respect to the order of detection in transmission and fluorescence; in general they are not symmetric.
Spectra of the atomic resonance fluorescence and of the cavity-transmitted light in a driven Jaynes-Cummings system are studied theoretically, where the cavity is driven by a classical field of arbitrary strength. In the regime of strong atom-cavity coupling, anomalous resonance peaks occur at $\ifmmode\pm\else\textpm\fi{}\sqrt{n}{g}^{\ensuremath{'}} (n=2,3,\dots{}),$ with the modified vacuum Rabi frequency ${g}^{\ensuremath{'}},$ both in the atomic fluorescence and the cavity transmission. These peaks as well as the observed shift of the vacuum Rabi splitting are explained in terms of the quasienergy levels induced dynamically by the strong driving field. For a stronger driving field, it is shown that the spectrum of the cavity transmission deviates from that of the atomic fluorescence. In the presence of significant damping, the spectrum of the cavity transmission approaches a singlet structure in the strong driving-field limit, and it is found additionally that a bimodal photon-number distribution, which results in a unique quintuplet spectrum of the atomic fluorescence, does not show up in the cavity transmission.
We consider an optical cavity containing a single two-level atom driven on resonance by an external laser source.1 We focus on the limit of weak excitation where the dynamic response of this system is governed by just three parameters: the atom-field coupling constant g, spontaneous emission rate γ for the atom, and cavity decay rate κ. The statistics of the transmitted light are analyzed as a function of g, γ, and κ, in terms of the second-order correlation function g(2)(τ), and the quadrature variances measured in a homodyne detection scheme. Squeezing and photon antibunching exist over a wide range of parameters. For γ ~ κ, the system can exhibit an oscillatory response, even when the mean intracavity photon number is much less than unity.2 The oscillations can be understood in terms of the coupling between the free atom-field eigenstates |0,−>, |0,+>, and |1,−>. The oscillation frequency is determined by the energy level splitting produced between the degenerate one-quantum states |0,+> and |1,−> by the atom-field interaction. The second-order correlation function can exhibit a novel nonclassical effect, where, for g(2)(0) ≠ 0, at some finite delay τ0, the correlation function dips exactly to zero—g(2)(τ0) = 0.