Quantum interference and phase-dependent fluorescence spectrum of a four-level atom with antiparallel dipole moments

Abstract

We investigate the effects of spontaneously generated interference on the spectrum of quantum fluctuations in phase quadratures of resonant fluorescence emitted from the transition of j = 1/2 to j = 1/2 of a monochromatically driven four-level atom with antiparallel dipole moments. It is found that the spectrum exhibits obvious characteristics of quantum interference in both cases of weak and strong laser fields. For the Zeeman-degenerate system, strong radiation squeezing in weak atomic excitation can occur at the central frequency of the spectrum, which is quite different from the case without consideration of the interference. Moreover, when we apply an external magnetic field to the atom, we find that the quantum interference can lead to a narrowing spectrum with much stronger squeezing by adjusting the magnetic field strength. These results suggest that the phase-dependent fluorescence spectrum can serve as a probe of the quantum interference effects in a realistic system such as a trapped 198Hg+ ion or charged quantum dots.

Squeezing in resonance fluorescence via vacuum induced coherences

“…As shown by the solid curves in figure 3, the squeezing appears in both quadratures as a consequence of VIC. This result is in contrast to that of Tan et al [27] where VIC induces squeezing only in the out-of-phase quadrature for weak resonance excitations.…”

“…The results are also compared with the case when there is no additional σ − -polarized light driving the atom. In the absence of the additional field (Ω b = 0), the squeezing spectrum S π (ω, θ) is the same as that of a two-level atom as reported by Tan et al [27]. As shown by the dashed curves in figure 2, the spectrum S π (ω, 0) exhibits twomode squeezing (for Ω b = 0) at the Rabi sideband frequencies Ω ′ = ± 4Ω 2 a + ∆ 2 , which is the well-known feature of a driven two-level atom for off-resonance excitations [11].…”

Fluorescence control through vacuum induced coherences

“…In the numerical calculations, the spectra S π (ω) and S σ (ω) are obtained using Eqs. ( 25) and (26). All the parameters such as Rabi frequencies, detuning, and the decay rates are scaled by the total decay rate γ.…”

“…1 Since the spontaneous decays along the π-transition channels |1 → |3 and |2 → |4 occur via common vacuum modes, VIC exists in this system. In the previous studies, the fluorescence properties of the atom were investigated considering only a linearly polarized light driving the π transitions [21,22,[25][26][27]. In the present work, we extend this analysis to include an additional σ − -polarized light driving the atom.…”

Modification of the Electromagnetic Field in the Photonic Crystal Medium and New Ways of Applying the Photonic Band Gap Materials

“…Quantum interference among different decay channels caused by the anisotropic vacuum is the major field of research. Several ways have been proposed to create the anisotropy and to provide interference between atomic levels in such materials as negative-index materials [38][39][40][41][42][43], metasurfaces [44], hyperbolic metamaterials [45], metallic nanostructures [46,47], topological insulators [48], and external fields [49][50][51]. The possibility for making use of anisotropy in the PC medium for these purposes has been investigated in Refs.…”