Spectral and squeezing properties of the resonance fluorescence of two coupled quantum dots forming an effective Λ-type three-level structure and connected with two normal metal leads are studied. We assume that one of the dots is driven by a strong light field and find that by modulating the bias voltage and the dot-lead coupling strengths, the electron can be selectively trapped in one of the two dressed states produced by the light field. The trapped electron possesses large coherence, and the resulting unbalanced dressed-state populations can lead to a significant enhancement or suppression of the sidebands in the resonance fluorescence spectrum. Moreover, a wideband squeezing can be generated that may be significantly enhanced by modulating the gate voltage.
Spectral and squeezing properties of the resonance fluorescence of two coupled quantum dots forming an effective Λ-type three-level structure and connected with two normal metal leads are studied. We assume that one of the dots is driven by a strong light field and find that by modulating the bias voltage and the dot-lead coupling strengths, the electron can be selectively trapped in one of the two dressed states produced by the light field. The trapped electron possesses large coherence, and the resulting unbalanced dressed-state populations can lead to a significant enhancement or suppression of the sidebands in the resonance fluorescence spectrum. Moreover, a wideband squeezing can be generated that may be significantly enhanced by modulating the gate voltage.
The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency.
The fluorescence field from one of the two allowed transitions in a three-level atom can sense squeezed fluctuations of a vacuum field coupled to the other transition. We examine the fluorescence spectra of strongly driven three-level atoms in \ensuremath{\Lambda}, V, and cascade configurations in which one of the two one-photon transitions is coupled to a finite-bandwidth squeezed vacuum field, when the bandwidth is much smaller than the difference in the atomic transition frequencies, though much larger than atomic decay rates and Rabi frequencies of the driving fields. The driving fields are on one-photon resonance, and the squeezed vacuum field is generated by a degenerate parameter oscillator. Details are only given for the \ensuremath{\Lambda} configuration. The extension to the V and cascade configurations is straightforward. We find that in all configurations the fluorescence spectra of the transition not coupled to the squeezed vacuum field are composed of five lines, one central and two pairs of sidebands, with intensities and widths strongly influenced by the squeezed vacuum field. However, only the central component and the outer sidebands exhibit a dependence on the squeezing phase. We also examine the fluorescence spectrum for the cascade configuration with a squeezed vacuum field on resonance with the two-photon transition between the ground and the most excited states and now generated by a nondegenerate parametric oscillator. In this case, where the squeezed vacuum field can be made coupled to both transitions, all spectral lines depend on the squeezing phase. The spectral features are explained in terms of the dressed-atom model of the system. We show that the coherent mixing of the atomic states by the strong driving fields modifies transition rates between the dressed states, which results in the selective phase dependence of the spectral features. \textcopyright{} 1996 The American Physical Society.
Metal nanoparticles (MNPs) possess the intriguing property of enhancing and limiting the energy of light field to subwavelength scale, which have attracted extensive attention in physics, chemistry, and life sciences. Meanwhile, squeezing is a general concept in quantum optics and can be used to engineer matter interaction scenarios. Here we consider an artificial hybrid molecule consisting of an MNP interacting with a semiconductor quantum dot (QD), combining with a squeezed reservoir. Using experimentally realistic parameters for the MNP-QD architecture and fully quantized approach, we theoretically explore the optical properties of the hybrid molecule driven by an external applied laser field via probing the resonance fluorescence in the steady state. We show that in this way it is possible to engineer and control the peak-value magnitudes, widths, and shapes of the resonance fluorescence spectra under the influence of the squeezed vacuum field without the need for the strong-coupling condition between the MNP and QD. In particular, some interesting phenomena in rich spectral responses are attainable, including Fano-type resonance fluorescence, fluorescence quenching, fluorescence narrowing, and fluorescence enhancement. Our method can also be extended to other nanoscopic structures, such as a plasmonic nanoantenna coupled to an emitter. These unique line shapes obtained here may have potential applications in developing quantum plasmonic platforms and sensitive on-chip devices such as optical switches and sensors.
Abstract The squeezing spectrum of the fluorescence field emitted from a four-level atom in J = 1/2 to J = 1/2 configuration driven by two coherent fields is studied. We find that the squeezing properties of the fluorescence radiation are significantly influenced by the presence of vacuum-induced coherence in the atomic system. It is shown that such coherence induces spectral squeezing in phase quadratures of the fluorescence light for both weak and strong driving fields. The dependence of the squeezing spectrum on the relative phase of the driving fields is also investigated. Effects such as enhancement or suppression of the squeezing peaks are shown in the spectrum as the relative phase is varied. An analytical explanation of the numerical findings is presented using dressed-states of the atom-field system.
Quantum optics provides a fundamental framework for understanding the interaction between light and matter at the quantum level. Recently, it has been shown that under incoherent pumping, the resonance fluorescence spectrum dramatically changes. Engineering the resonance fluorescence spectrum paves the way towards solid-state-based single-photon sources. In this paper, we start by reviewing and reproducing some of the results concerning the resonance fluorescence spectrum, single-photon sources, dressed-state lasers, and luminescence spectrum of a quantum dot in a microcavity. Photon correlations in quantum optical systems and spectral properties of radiation emitted by atomic and semiconductor systems interacting with external fields are investigated. The well known Mollow triplet structure of the emission spectrum is discussed, together with the role of dressed states in explaining the origin of the three spectral peaks. Furthermore, the luminescence spectra of quantum emitters coupled to microcavities are reviewed. The numerical results presented here contribute to the theoretical understanding of resonance fluorescence, photon correlations, and engineered emission in quantum optical systems. These studies highlight the rich physical properties arising from light matter interaction at the quantum level and demonstrate their relevance for emerging quantum technologies.
We examine resonance fluorescence of a two-level atom in a squeezed vacuum, under the condition that the squeezing bandwidth is much narrower than the Rabi splitting of the Mollow triplet. For a suitable choice of the relative phase between the squeezed vacuum and coherent driving field, we find significant narrowing of the Rabi peaks and inhibited population decay. These results are in marked contrast to previous broadband squeezing analyses, which predict strong broadening of the Rabi peaks and enhanced population decay. We explore the connection between our work and that on the dynamical suppression of spontaneous emission via strongly driven resonance fluorescence in a cavity [Lewenstein, Mossberg, and Glauber, Phys. Rev. Lett. 59, 775 (1987)]. By modifying this work to incorporate squeezing of the cavity modes, we are able to combine the features of both systems, and thereby predict strong inhibition of the decay of all three components of the Bloch vector in a possible experimental configuration.