Resonance Fluorescence Spectrum Research Articles

Asymmetricity in fluorescence peaks of a three level Λ-type quantum emitter placed near a spherical metal nanoparticle

Abstract A generalized master equation is derived here for a hybrid three level Λ-type quantum emitter-metal nanoparticle (MNP) system in the presence of strong external fields. With this new master equation, we show the spectral reshaping of the fluorescence peaks leading to asymmetric peak heights. This asymmetricity is attributed to dressed state-reservoir coupling and strong coherent fields. The coupling of reservoir with dressed states results in different sampling of local density of states (LDOS) of the vacuum field by dressed state transitions, giving different transition probabilities to each peak. We have further explored the directional features of the resonance fluorescence spectrum in the hybrid system. These observations of spectral reshaping in a three-level-MNP system opens new directions for studying tunable electromagnetically induced transparency utilizing ‘tailored vacuum’ in quantum plasmonics.

Natural-linewidth measurements of the 3C and 3D soft-x-ray transitions in Ni xix

We used the monochromatic soft-x-ray beamline P04 at the synchrotron-radiation facility PETRA III to resonantly excite the strongest 2p−3d transitions in neonlike Ni ions, [2p6]J=0→[(2p5)1/23d3/2]J=1 and [2p6]J=0→[(2p5)3/23d5/2]J=1, respectively dubbed 3C and 3D, achieving a resolving power of 15 000 and signal-to-background ratio of 30. We obtain their natural linewidths, with an accuracy of better than 10%, as well as the oscillator-strength ratio f(3C)/f(3D)=2.51(11) from analysis of the resonant fluorescence spectra. These results agree with those of previous experiments, earlier predictions, and our own advanced calculations. Published by the American Physical Society 2024

Resonance fluorescence in Λ, V and Ξ - type three-level configurations

We theoretically study the resonance fluorescence spectra of the lambda (Λ), vee (V) and cascade (Ξ) type three-level configurations. It is shown that each system with two detuning frequencies can be modelled using the SU(3) symmetry group to derive a generalized optical Bloch equation. For each configuration, this equation is solved to calculate the two-time correlation function by invoking the quantum regression theorem. The incoherent part of the power spectra gives the characteristic multi-peak fluorescence profiles which are different for different configurations. We also discuss how the dressed-state structure of such system can explain the origin of quintuplet profile of the fluorescent spectrum.

Theoretical analysis of the resonance fluorescence correlation spectrum of three-level multi-mer 85Rb atomic system

In a vapor cell, [Formula: see text] is the average velocity of the moving atoms. When [Formula: see text], the in-homogeneous broadening of the atomic spectral lines is important when taking into account thermal Doppler broadening. We also discover that the narrowing mechanism for inter-atomic with different components has more influence on the Doppler line-shape. Thus, the spectral line broadening of two-level and three-level multi-mer [Formula: see text] atom is not only influenced by the in-homogeneous Doppler broadening, but also affected by the Dicke narrowing effect. The fluorescence spectrum affords a good possibility for a detailed study of Dicke narrowing effect and thermal Doppler broadening effect. We analyze the influence of multi-mer [Formula: see text] atomic system component on resonance fluorescence spectrum (RFS). Based on the quantum regression theorem, we develop a method and derive a general analytical expression for the two-dimensional (2D) fluorescence correlation spectrum of three-level [Formula: see text] atomic system.

Resonance fluorescence of noisy systems

Light scattering from resonantly or nearly resonantly excited systems, known as resonance fluorescence (RF), has been gaining importance as a versatile tool for investigating quantum states of matter and readout of quantum information, recently including also the inherently noisy solid state systems. In this work we develop a general theory of RF in the low excitation limit on systems in which the transition energy is subject to noise for two important classes of noise processes: white noise fluctuations that lead to phase diffusion and an arbitrary stationary Markovian noise process on a finite set of states. We apply the latter to the case of random telegraph noise (TN) and a sum of an arbitrary number of identical random TN contributions. We show that different classes of noise influence the RF spectrum in a characteristic way. Hence, the spectrum carries information on the characteristics of noise present in the physical system.

Independent Electrical Control of Two Quantum Dots Coupled through a Photonic-Crystal Waveguide.

Efficient light-matter interaction at the single-photon level is of fundamental importance in emerging photonic quantum technology. A fundamental challenge is addressing multiple quantum emitters at once, as intrinsic inhomogeneities of solid-state platforms require individual tuning of each emitter. We present the realization of two semiconductor quantum dot emitters that are efficiently coupled to a photonic-crystal waveguide and individually controllable by applying a local electric Stark field. We present resonant transmission and fluorescence spectra in order to probe the coupling of the two emitters to the waveguide. We exploit the single-photon stream from one quantum dot to perform spectroscopy on the second quantum dot positioned 16 μm away in the waveguide. Furthermore, power-dependent resonant transmission measurements reveal signatures of coherent coupling between the emitters. Our work provides a scalable route to realizing multiemitter collective coupling, which has inherently been missing for solid-state deterministic photon emitters.

Discovery of the Quinoxalinone-B(C6F5)3·H2O Combo as a Photocatalyst by Acidochromism Strategy: Aerobic Oxidation of Alcohol, Alkene, and Thiols.

Modification of photocatalyst reactivity through intermolecular interactions represents a straightforward and convenient strategy for catalyst designation. Herein, we reported that upon the addition of B(C6F5)3·H2O, the oxidation potential of quinoxalinone increased remarkably, enabling the photoredox aerobic oxidation of alcohol, thiols, and alkenes toward carbonyl compounds and dithioethers under visible light conditions. Mechanistic studies, including X-ray structure analysis, cyclic voltammetry, electron paramagnetic resonance measurements, UV-vis absorption, and fluorescence spectra, revealed that the quinoxalinone-B(C6F5)3·H2O combo could serve as a versatile photocatalyst for both energy transfer and single electron transfer processes.

How to Read Out the Phonon Number Statistics via Resonance Fluorescence Spectroscopy of a Single‐Photon Emitter

AbstractIn today's development of quantum technologies a hybrid integration of phononic excitations becomes increasingly attractive. As natural quasi‐particle excitations in solid state systems, phonons couple to virtually any other excitation and therefore constitute a useful interaction channel between different building blocks in hybrid quantum systems. This work explores how the efficient light‐scattering properties of a single‐photon emitter and the appearance of characteristic sidebands in resonance fluorescence spectra, when interfaced with an arbitrary phonon quantum state, can be utilized for acousto‐optical transduction. Within reasonable approximations, an analytical description for the optical spectra in the low excitation limit is developed which can be used to read the number statistics of the initial phonon state from a given spectrum. It is shown that the readout is faulty in situations where relevant resonant transitions are forbidden due to vanishing Franck–Condon factors, especially when considering spectra with a noisy background. Two possible solutions to this problem are presented: (A) changing the detuning of the laser relative to the single‐photon emitter which modifies the relevant resonant transitions, or (B) increasing dissipation of the single‐photon emitter to promote off‐resonant transitions.

Kernelizing: A way to increase accuracy in trilinear decomposition analysis of multiexponential signals

The unmixing of multiexponential decay signals into monoexponential components using soft modelling approaches is a challenging task due to the strong correlation and complete window overlap of the profiles. To solve this problem, slicing methodologies, such as PowerSlicing, tensorize the original data matrix into a three-way data array that can be decomposed based on trilinear models providing unique solutions. Satisfactory results have been reported for different types of data, e.g., nuclear magnetic resonance or time-resolved fluorescence spectra. However, when decay signals are described by only a few sampling (time) points, a significant degradation of the results can be observed in terms of accuracy and precision of the recovered profiles.In this work, we propose a methodology called Kernelizing that provides a more efficient way to tensorize data matrices of multiexponential decays. Kernelizing relies on the invariance of exponential decays, i.e., when convolving a monoexponential decaying function with any positive function of finite width (hereafter called “kernel”), the shape of the decay (determined by the characteristic decay constant) remains unchanged and only the preexponential factor varies. The way preexponential factors are affected across the sample and time modes is linear, and it only depends on the kernel used. Thus, using kernels of different shapes, a set of convolved curves can be obtained for every sample, and a three-way data array generated, for which the modes are sample, time and kernelizing effect. This three-way array can be afterwards analyzed by a trilinear decomposition method, such as PARAFAC-ALS, to resolve the underlying monoexponential profiles. To validate this new approach and assess its performance, we applied Kernelizing to simulated datasets, real time-resolved fluorescence spectra collected on mixtures of fluorophores and fluorescence-lifetime imaging microscopy data. When the measured multiexponential decays feature few sampling points (down to fifteen), more accurate trilinear model estimates are obtained than when using slicing methodologies.

Two-level atom dynamics induced by a spin-orbit coupled optical vortex: dressed states formulation

We consider here the interaction of a two-level atom with a tightly focused paraxial optical vortex beam in the dressed states formalism. The interaction is characterized by a term that couples the photon spin angular momentum (SAM) with its orbital angular momentum (OAM). This term affects all the physical quantities related to the dressed states, like their energies, populations, and relaxation rates among them. We also show that the Mollow triplet associated with the resonance fluorescence spectrum of a two-level atom acquires a chiral character. We give numerical examples based on experimentally accessible values of the various parameters, and we show that the chirality can give rise to observable modifications of the various physical quantities under consideration.

Controllable sidebands of resonance fluorescence of a two-level system driven by bichromatic field

Strong polychromatic driving reshapes characteristics of the resonance fluorescence spectrum of a two-level system. Employing bichromatic driving feild with a low beat-frequency smaller than the emission rate of the system we demonstrate the exotic features of the fluorescence spectrum calculated by the numerical Floquet-Liouville approach and analytical method. It is found that fluorescence spectrum possesses two broadened sidebands in the place of the Rabi sidebands under certain conditions. Moreover, the heights and widths of the sidebands can be controlled by tuning the driving parameters. The properties of the spectrum is determined by the transitions between the Floquet states in a rotating frame. The broadened sidebands result from the quasi-continuous quasienergy spectrum which happens with steering the beat frequency lower. The present study provides insights into the Floquet engineering of the fluorescence spectral features with polychromatic excitation fields.

Discerning the transition from electromagnetically induced transparency to Autler–Townes splitting using the decaying dressed state formalism

We use biorthogonal basis consisting of the ‘right’ and ‘left’ eigenvectors of the effective non-Hermitian Hamiltonian of a three-level system driven by a bi-chromatic field, and resolve the probe absorption spectrum into components corresponding to the decaying dressed states of the system. It is observed that the spectrum primarily consists of three components and two of them undergo dramatic changes when the control field Rabi frequency is changed from the low to high field regime. Based on the symmetry properties of a combination of these components, a parameter internal to the dynamics of the system is defined and is used to distinguish between electromagnetically induced transparency (EIT) and Autler–Townes (AT) splitting, and the threshold for transition between them in an objective manner. The formulation is further extended to the resonance fluorescence spectrum on the probe transition in the EIT and AT regimes.

Controlling Resonance Fluorescence Spectra and Photon Statistics in a Driven V-Type Quantum Emitter—Metal Nanoparticle Coupled Structure

We study the resonant fluorescence emission spectrum and the intensity-intensity correlations of the emitted fluorescent field by a V-type quantum emitter (QE) which is located near a metal nanosphere. For the description of the studied phenomena, we use the density matrix equations methodology combined with electromagnetic calculations and obtain results for the profile of the resonant fluorescence spectrum and the second-order correlation functions associated with the fluorescent photons. The decay rates and the coupling term exhibit a strong dependence on the distance that separates the QE from the metal nanoparticle. This distance also influences the resonance fluorescence of the V-type QE. We find that, in the general case, the resonant fluorescence spectrum is composed of five Lorentzian-type peaks, for high interparticle distances, while, when the QE is located very close to the surface of the nanosphere, the central resonance becomes dominant, and a single-peaked spectral profile appears. The two-time correlation functions of the fluorescent photons evolve in an oscillatory manner around unity, for non-zero time delay, with a period that decreases with the increase of the field intensity. In the strong driving field regime, the antibunching to bunching crossing time does not depend on the interparticle distance, contrary to the results found in the weak driving field regime. We also find that, for a weak laser field and under specific conditions, the second-order correlation functions constantly remain in the antibunching region.

A mechanism of compass-free migratory navigation

How migratory birds can find the right way when navigating over thousands of miles is an intriguing question that has greatly interested researchers in both the fields of biology and physics for centuries. There are several putative proposals that sound intuitively plausible; all remain contested so far because these hypothetical models of magnetoreceptors that sense the geomagnetic field need either extremely high sensitivity or humankind-like intelligence to guide. Here we explore theoretically whether birds can navigate to their destination through an entirely new scenario to sense the geomagnetic field. Our proposal is based on separate peaks of the resonance-fluorescence spectrum of a four-level system derived from the ferric sulfide cluster that exists in a MagR/Cry protein complex (Drosophila CG8198) of migratory birds. As the separation of spectral peaks contains information about the geomagnetic field at both the current location and the birthland, the change of such separation cues the bird to choose the right direction to move, and double-resonance emerges once it has arrived at its destination. Our theoretical mechanism can explain previous experiments on the disorientation of migratorybirds caused by oscillating magnetic field naturally and more precisely. This work provides insight into explaining migratory navigation and motivates possible humanmade practical devices.

Спектры поглощения пробного сигнала и резонансной флуоресценции для излучателей при их взаимодействии с локальным окружением в прозрачных средах

The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong monochromatic cw laser. The sensitivity of absorption and emission optical spectroscopy method is compared for revealing the effects of the medium on individual emitters and their ensembles. Spectral curves were calculated for model emitters considering local field influence of a transparent dielectric medium and local electron-phonon interactions, which determined the response of the emitters to an external laser field and effective relaxation mechanisms. The calculation formalism is based on a semiclassical approach, while the relaxation processes associated with the phonon contribution are introduced phenomenologically with references to other studies.

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The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong monochromatic cw laser. The sensitivity of absorption and emission optical spectroscopy method is compared for revealing the effects of the medium on individual emitters and their ensembles. Spectral curves were calculated for model emitters considering local field influence of a transparent dielectric medium and local electron-phonon interactions, which determined the response of the emitters to an external laser field and effective relaxation mechanisms. The calculation formalism is based on a semiclassical approach, while the relaxation processes associated with the phonon contribution are introduced phenomenologically with references to other studies.

The Effect of Collisions on the Resonance Fluorescence Spectrum of Three-Level Atoms with a V-Configuration of Levels

The Effect of Collisions on the Resonance Fluorescence Spectrum of Three-Level Atoms with a V-Configuration of Levels

The Doppler shifts of resonant fluorescence spectrum for a two-level $$ ^{{{85}}} $$Rb atom via multiphoton Compton scattering

Usually, it's difficult for us to observe the Compton Scattering in an atom. One way to overcome this difficult is using multi-photon collide with an atom, which will come into being multi-photon Compton Scattering (MCS) phenomenon. Thus, we can investigate the MCS process in visible light region. During the MCS process, the cluster atoms moving as a whole, namely atomic Dicke states, the multi-photon interacting with cluster atoms. We can observe a significant Doppler shift of resonant fluorescence spectrum(RFS)in a room-temperature two-levelatomic system. In this paper, we present a detail analysis of the physics mechanism of the Doppler shift and propose a method to measure the component of the Dicke states (the atomic polymers with different masses)by using the Doppler shift of the RFS.

Two-photon resonance fluorescence of two interacting nonidentical quantum emitters

We study a system of two interacting, nonidentical quantum emitters driven by a coherent field. We focus on the particular condition of two-photon resonance and obtain analytical expressions for the stationary density matrix of the system and observables of the fluorescent emission. Importantly, our expressions are valid for the general situation of nonidentical emitters with different transition energies. Our results allow us to determine the regime of parameters in which coherent two-photon excitation, enabled by the coherent coupling between emitters, is dominant over competing, first-order processes. Using the formalism of quantum parameter estimation, we show that the features imprinted by the two-photon dynamics into the spectrum of resonance fluorescence are particularly sensitive to changes in the distance between emitters, making two-photon excitation the optimal driving regime for the estimation of interemitter distance. This can be exploited for applications such as super-resolution imaging of pointlike sources.

Quantum Optics in Nanostructures.

This review is devoted to the study of effects of quantum optics in nanostructures. The mechanisms by which the rates of radiative and nonradiative decay are modified are considered in the model of a two-level quantum emitter (QE) near a plasmonic nanoparticle (NP). The distributions of the intensity and polarization of the near field around an NP are analyzed, which substantially depend on the polarization of the external field and parameters of plasmon resonances of the NP. The effects of quantum optics in the system NP + QE plus external laser field are analyzed—modification of the resonance fluorescence spectrum of a QE in the near field, bunching/antibunching phenomena, quantum statistics of photons in the spectrum, formation of squeezed states of light, and quantum entangled states in these systems.