Atomic Resonance Fluorescence Research Articles

Resonance Fluorescence of a Chiral Artificial Atom

Resonance Fluorescence of a Chiral Artificial Atom

Master equations and quantum trajectories for squeezed wave packets

The interaction between matter and squeezed light has mostly been treated within the approximation that the field correlation time is small. Methods for treating squeezed light with more general correlations currently involve explicitly modeling the systems producing the light. We develop a general purpose input-output theory for a particular form of narrowband squeezed light -- a squeezed wave-packet mode -- that only cares about the statistics of the squeezed field and the shape of the wave packet. This formalism allows us to derive the input-output relations and the master equation. We also consider detecting the scattered field using photon counting and homodyne measurements which necessitates the derivation of the stochastic master equation. The non Markovian nature of the field manifests itself in the master equation as a coupled hierarchy of equations. We illustrate these with consequences for the decay and resonance fluorescence of two-level atoms in the presence of such fields.

Simulating quantum interference effects in the fluorescence of a V-system with perpendicular dipole moments

We present a scheme that enables the observation of interference effects in the resonance fluorescence of a V-type atom with orthogonal dipole moments. Specifically, we consider the atomic configuration of a J g = 0 to J e = 1 transition driven by a single laser field. By employing polarization-sensitive detection in such a way that the light emitted on the two transitions become indistinguishable, we show that one can simulate the effect of vacuum-induced coherence on the resonance fluorescence of this system. In addition, we demonstrate the possibility of realizing atomic transitions with both parallel and antiparallel dipole moments and their effects on the fluorescence spectrum. The interference induced leads to interesting features in the fluorescence spectrum such as asymmetric spectral peaks, enhancement and suppression of the sidebands, and disappearance of fluorescence in the particular direction of detection. The numerical results are understood in the context of the dressed states of the combined atom–field system.

Phase-dependent fluctuations of resonance fluorescence near the coherent population trapping condition

We study phase-dependent fluctuations of the resonance fluorescence of a single Λ-type three-level atom in the regime near coherent population trapping, i.e. alongside the two-photon detuning condition. To this end, we employ the method of conditional homodyne detection (CHD) which considers squeezing in the weak driving regime, and extends to non-Gaussian fluctuations for saturating and strong fields. In this framework, and using estimated parameter settings of the resonance fluorescence of a single trapped 138Ba+ ion, the light scattered from the probe transitions is found to manifest a non-classical character and conspicuous asymmetric third-order fluctuations in the amplitude-intensity correlation of CHD.

Heterogeneous Reaction of Dimethyl Sulfide with Iodine Oxide in a Temperature Range of 291–365 K

A reaction of the iodine oxide (IO) radical with dimethyl sulfide (DMS) in a temperature range of 291–365 K was studied using atomic iodine resonance fluorescence. It was found that this reaction was mainly heterogeneous under the experimental conditions, and the rate constant of the heterogeneous reaction was almost an order of magnitude higher than the rate constant of a homogeneous reaction. The temperature dependence of the rate constant of this reaction can be represented by the following expression: k(T) = 1.5 × 10–14 [±3 × 10–15 cm3 molecule–1 s–1] exp(7150[±800 J/mol]/RT). The conditions under which the heterogeneous reaction of DMS with the IO radical can play a noticeable role in the oxidation of DMS in the atmosphere are discussed.

Kinetic fall-off behavior for the Cl + Furan-2,5-dione (C4H2O3, maleic anhydride) reaction.

Rate coefficients, k, for the gas-phase Cl + Furan-2,5-dione (C4H2O3, maleic anhydride) reaction were measured over the 15-500 torr (He and N2 bath gas) pressure range at temperatures between 283 and 323 K. Kinetic measurements were performed using pulsed laser photolysis (PLP) to produce Cl atoms and atomic resonance fluorescence (RF) to monitor the Cl atom temporal profile. Complementary relative rate (RR) measurements were performed at 296 K and 620 torr pressure (syn. air) and found to be in good agreement with the absolute measurements. A Troe-type fall-off fit of the temperature and pressure dependence yielded the following rate coefficient parameters: ko(T) = (9.4 ± 0.5) × 10-29 (T/298)-6.3 cm6 molecule-2 s-1, k∞(T) = (3.4 ± 0.5) × 10-11 (T/298)-1.4 cm3 molecule-1 s-1. The formation of a Cl·C4H2O3 adduct intermediate was deduced from the Cl atom temporal profiles and an equilibrium constant, KP(T), for the Cl + C4H2O3 ↔ Cl·C4H2O3 reaction was determined. A third-law analysis yielded ΔH = -15.7 ± 0.4 kcal mol-1 with ΔS = -25.1 cal K-1 mol-1, where ΔS was derived from theoretical calculations at the B3LYP/6-311G(2d,p,d) level. In addition, the rate coefficient for the Cl·C4H2O3 + O2 reaction at 296 K was measured to be (2.83 ± 0.16) × 10-12 cm3 molecule-1 s-1, where the quoted uncertainty is the 2σ fit precision. Stable end-product molar yields of (83 ± 7), (188 ± 10), and (65 ± 10)% were measured for CO, CO2, and HC(O)Cl, respectively, in an air bath gas. An atmospheric degradation mechanism for C4H2O3 is proposed based on the observed product yields and theoretical calculations of ring-opening pathways and activation barrier energies at the CBS-QB3 level of theory.

Kinetics of a Heterogeneous Reaction of Hydrogen Sulfide with Iodine Oxide in the Temperature Range of 273 to 368 K

The reaction of radical of iodine oxide (IO) with hydrogen sulfide in the temperature range of 273 to 368 K is studied by the method of resonance fluorescence of iodine atoms. The temperature dependence of the rate constant of this reaction is described by the expression kII(T) = (1.6 ± 0.3) × 10–14exp(1035/T) cm3 molecule–1 s–1. It is proved that these substances react mainly on the wall of the reactor. The possibility is discussed that these substances react in the sea and coastal zones.

Influence of an electric field on Rydberg nD states of cold lithium atoms

Influence of a weak electric field on the coherent Rydberg resonances was studied on two-photon transitions 2S–nD by recording the resonance fluorescence of lithium atoms in a magneto-optical trap. It was observed that an isolated spectral line 2P–nD transferred to the spectral band width growing with a principal number n (or an electric field E). It was shown that the frequency tuning of a resonant radiation on the left (right) edge of the band allows to create a gas of Rydberg atoms with fixed and large dipole moments d ∝ ea 0 n 2 (e is the elementary charge, a 0 is the Bohr radius), oriented against (along) the electric field. The radiation frequency was tuned on the center of the band would produced atomic states with zero dipole moments, but with a big contribution of states with maximum angular momentum quantum number l ~ n.

Multipath interference from large trapped ion chains

The demonstration of optical multipath interference from a large number of quantum emitters is essential for the realization of many paradigmatic experiments in quantum optics. However, such interference remains still unexplored as it crucially depends on the sub-wavelength positioning accuracy and stability of all emitters. We present the observation of controlled interference of light scattered from strings of up to 53 trapped ions. The light scattered from ions localized in a harmonic trapping potential is collected along the ion crystal symmetry axis, which guarantees the spatial indistinguishability and allows for an efficient scaling of the contributing ion number. We achieve the preservation of the coherence of scattered light observable for all the measured string sizes and nearly-optimal enhancement of phase sensitivity. The presented results will enable realization and control of directional photon emission, direct detection of enhanced quadrature squeezing of atomic resonance fluorescence, or optical generation of genuine multi-partite entanglement of atoms.

N(4S3/2) reaction with NO and NO2: Temperature dependent rate coefficients and O(3P) product yield

The N(4S3/2) + NO (k1) and N(4S3/2) + NO2 (k2) gas-phase reactions, relevant to upper-atmospheric NOx chemistry, were studied using a discharge flow tube reactor with atomic resonance fluorescence detection of O(3P) atoms. Reaction rate coefficients were measured over the temperature range 216–344 K to be k1(T) = (2.61 ± 0.19) × 10−11 exp((86 ± 21)/T) and k2(T) = (2.41 ± 0.62) × 10−12 exp((442 ± 64)/T) cm3 molecule−1 s−1. The O(3P) yield in the NO2 reaction was found to be 0.66 ± 0.06. Our results are compared with previous studies and rate coefficient recommendations are provided.

Fluorescence control through vacuum induced coherences

The resonance fluorescence of a four-level atom in J = 1/2 to J = 1/2 transition driven by two coherent fields is studied. We find that the incoherent fluorescence spectrum shows a direct indication of vacuum-induced coherence in the atomic system. We show that such coherence manifests itself via an enhancement or suppression of the spectral peaks in the π-polarized fluorescence. The effect of the relative phase of the driving fields on the spectral features is also investigated. We show that phase-dependent enhancement or suppression of the fluorescence peaks appears in the incoherent spectrum emitted along the σ transitions. It is found that this phase dependence occurs because of the polarization-detection scheme employed for the observation of the fluorescence light. We present an analytical explanation, based on dressed-states of the atom-field system, to interpret the numerical results.

Monitoring for time ordering and time asymmetry of spectral correlations in filtered resonance fluorescence generated from a Λ -type atomic system

Frequency-resolved correlation (FRC) is investigated in fluorescent emission radiated from a $\mathrm{\ensuremath{\Lambda}}$-type atomic system by employing weak coupling regime between quantum emitter and cavities, in which each cavity substituting a Lorentzian filter is assumed to pass through only one fluorescent photon at a time so that the analytical discussions for time orderings can be carried out in a truncated Hilbert space with single-excitation state for each cavity mode. In the limit of bad cavity (large passband width of filter) and short delay, the conditional time ordering amplitudes are introduced with the help of conditioned dressed atom-photon states prepared by preselection to probe into the effect of preferential screening for time orderings of filter-detector systems. Meanwhile, the past quantum state formalism is also applied in FRC to further excavate their collective monitoring effect. Based on the obtained two-mode correlation signals, it is found that, in nonresonant two-photon cascaded processes, bunching and antibunching can appear in two opposite detection orderings, respectively, and can be switched. The physical origin is explored that the two different transition amplitudes of emitted photons from a common spectral band of resonance fluorescence are responsible for opposite time orderings, thus, the imbalance between two complementary time orderings can be enhanced, which is impossible to achieve in resonance fluorescence of two-level atoms. This mechanism is embodied in the conditional time ordering amplitudes produced by this detection theory of cavity modes.

Fully relativistic description of the power spectrum

Resonance fluorescence of laser-driven atoms is studied in the relativistic regime by solving the time-dependent Dirac equation in a multi-level model. Electron spin and retardation of the electron–photon interaction give rise to new phenomena such as splitting of sideband peaks and modification of the Rabi oscillator frequencies not explainable in a nonrelativistic theory. In our theoretical investigation, we show how, by applying coherent light with x-ray frequencies, the relativistic fluorescence spectrum can be exploited to determine atomic multipole matrix elements.

Measurement of the Rate Constant of a Reaction of Chlorine Atoms with CH3Br in a Temperature Range of 298–358 K Using the Resonance Fluorescence of Chlorine Atoms

The rate constant of the reaction of chlorine atoms with CH3Br was measured in a temperature range of 298–358 K using the resonance fluorescence of chlorine atoms. The possible role of this reaction in atmospheric chemistry and fire extinguishing was discussed. It was found that this reaction is homogeneous in contrast to the previously studied reaction of chlorine atoms with CH3I, with occurs at the reactor surface.

Large time-asymmetric quantum fluctuations in amplitude–intensity correlation measurements of V-type three-level atom resonance fluorescence

In this paper we show that the scattered field of a bichromatically driven V-type three-level atom exhibit asymmetry and large violation of classical bounds in amplitude-intensity correlations. These features result from the noncommutativity of amplitude and intensity field operators, and the strong non-Gaussian fluctuations in this system. The amplitude-intensity correlations of resonance fluorescence, with its large third-order fluctuations, describe the nonclassical features of the emitted field more accurately than the second-order measure related to squeezing. Spectra and variances of these correlations, along intensity-intensity correlations, provide a wealth of supporting information.

Measurements of quantum defect in Rydberg D-states for lithium atoms

We have developed an effective spectroscopic method for measure the energy spectra of highly excited ultracold atoms using the registration of resonance fluorescence of atoms in magneto-optical trap during two-step cw excitation of Rydberg states by uv laser. Using this method it was obtained the value of the quantum defect was determined for Rydberg states nD of lithium-7 atoms δ = 0.00192(17).

Resonance fluorescence of a laser-cooled atom in a non-harmonic potential

We investigate a single laser driven atom trapped in a non-harmonic potential. We present the performance of ground-state laser cooling and Doppler cooling and the signatures of the center-of-mass motion in the power spectrum of the scattered light. In order to illustrate the results we provide two explicit examples for the confining potential: the infinite square well and the Morse potential.

Quantum defects in Rydberg nD states of optically cooled 7Li atoms

To observe Rydberg transitions we applied a spectroscopic technique based on the observation of the resonance fluorescence of cold atoms in a magneto-optical trap. By using this approach, we estimated the quantum defect in Rydberg nD states of 7Li atoms. The obtained results are in a good agreement with previously published data.

The stationary resonance fluorescence of a two-level atom in a cat-state field

We investigate the resonance fluorescence of a two-level atom placed in non-classical field which is a superposition of Glauber coherent states. The source of this superposition known under the common name of ‘Schrödinger cat‘-states is explicitly incorporated into the model. This let us to explore the stationary regime. In the strong (multiphoton) field limit the steady-state of the atom+photons system is found. We evaluated the spectrum of the resonance fluorescence. It appears to be one-component in contrast to the case with the classical external field.

Measuring the rate constant of the reaction between chlorine atoms and CHF2Br by Cl atom resonance fluorescence

The rate constant of the reaction between Cl atoms and CHF2Br has been measured by chlorine atom resonance fluorescence in a flow reactor at temperatures of 295–368 K and a pressure of ~1.5 Torr. Lining the inner surface of the reactor with F-32L fluoroplastic makes the rate of the heterogeneous loss of chlorine atoms very low (k het ≤ 5 s–1). The rate constant of the reaction is given by the formula k = (4.23 ± 0.13) × 10–12 e (–15.56 ± 1.58)/RT cm3 molecule–1 s–1 (with the activation energy in kJ/mol units). The possible role of this reaction in the extinguishing of fires producing high concentrations of chlorine atoms is discussed.