Atomic Resonance Research Articles

Quantum computing for atomic and molecular resonances.

The complex-scaling method can be used to calculate molecular resonances within the Born-Oppenheimer approximation, assuming that the electronic coordinates are dilated independently of the nuclear coordinates. With this method, one will calculate the complex energy of a non-Hermitian Hamiltonian, whose real part is associated with the resonance position and imaginary part is the inverse of the lifetime. In this study, we propose techniques to simulate resonances on a quantum computer. First, we transformed the scaled molecular Hamiltonian to second quantization and then used the Jordan-Wigner transformation to transform the scaled Hamiltonian to the qubit space. To obtain the complex eigenvalues, we introduce the direct measurement method, which is applied to obtain the resonances of a simple one-dimensional model potential that exhibits pre-dissociating resonances analogous to those found in diatomic molecules. Finally, we applied the method to simulate the resonances of the H2 - molecule. The numerical results from the IBM Qiskit simulators and IBM quantum computers verify our techniques.

Phonon lasing with an atomic thin membrane resonator at room temperature.

Graphene has been considered as one of the best materials to implement mechanical resonators due to their excellent properties such as low mass, high quality factors and tunable resonant frequencies. Here we report the observation of phonon lasing induced by the photonthermal pressure in a few-layer graphene resonator at room temperature, where the graphene resonator and the silicon substrate form an optical cavity. A marked threshold in the oscillation amplitude and a narrowing linewidth of the vibration mode are observed, which confirms a phonon lasing process in the graphene resonator. Our findings will stimulate the studies on phononic phenomena, help to establish new functional devices based on graphene mechanical resonators, and might find potential applications in classical and quantum sensing fields, as well as in information processing.

Reflection-type vapor cell for micro atomic clocks using local anodic bonding of 45° mirrors.

This Letter reports the design, fabrication, and evaluation of reflection-type planar vapor cells for chip-scale atomic clocks. The cell with 2-8 mm cavity length contains two 45° Bragg reflector mirrors assembled using a local anodic bonding. Coherent population trapping resonance of Rb atoms is observed, realizing an atomic clock operation. Allan deviations at an averaging time of 1 s are ${2.2} \times {{1}}{{{0}}^{- 10}}$ and ${9.5} \times {{1}}{{{0}}^{- 11}}$ for 2 mm long and 6 mm long vapor cells, respectively. These results show that planar vapor cells compatible with a system-in-package are feasible without degradation of clock stabilities compared to conventional vertically stacked cells.

Biological Effects of Soil Contamination Tracked in Caenorhabditis Elegans

Lead, arsenic, and glyphosate in soils may negatively affect inhabitants of the ecosystem. We hypothesize that analyzing the effects of each pollutant on worms in contaminated soil yields early insight into the possible bioaccumulation in organisms higher in the food chain. To test the effect of each contaminant on protein expression in N2 Caenorhabditis elegans worms and Escherichia coli were cultivated in soil in the presence of lead, glyphosate, and arsenic. Using atomic absorption spectrometry and nuclear magnetic resonance, contaminants were tracked within the organic samples. The presence of contaminants in soil was examined using scanning electron microscopy and electron dispersion spectroscopy. The effects of contaminants on protein expression in worms and E. coli was observed with two-dimensional electrophoresis.

Experimental studies on photoabsorption by endohedral fullerene ions with a focus on Xe@C60 + confinement resonances

A brief overview on the status of experimental investigations into photoionization and fragmentation of fullerenes and endohedral fullerenes by absorption of a single short-wavelength photon is presented. The focus of this paper is on the endohedral Xe@C60 + molecular ion in which a xenon atom is centrally encapsulated inside a fullerene cage. Confinement resonances that result from the interference of Xe photoelectron matter waves emerging from the cavity were studied by exposing Xe@C60 + ions to synchrotron radiation of 60 to 150 eV energy which is the region of the well-known giant atomic Xe excitation resonance. Photoions Xe@C n q+ (with final charge states of the product ions and numbers of carbon atoms left in the cage) were recorded as a function of photon energy and cross sections for the individual reaction channels were determined. In addition to previous work, new final channels ( and ) were observed, and thus, about 70% of the oscillator strength expected for the encapsulated Xe atom in the investigated energy range could be recovered. The present results establish the first and, so far, only conclusive experimental observation of confinement resonances in an endohedral fullerene. The data are in remarkable agreement with relativistic R-matrix calculations that accompanied the previous experimental work.

Coherent atomic mirror formed by randomly distributed ions inside a crystal.

Spatial distribution of atoms plays an important role in the interaction of atomic ensembles and electromagnetic fields. In this Letter, we show that by spatio-spectral tailoring of atomic absorption, one can effectively carve out a periodic array from randomly distributed atomic ensembles hosted by a solid-state crystal. Furthermore, we observe collective atomic resonances and coherent backscattering of light from rare-earth-doped crystals. Coherent backscattering as high as 20% was observed for light at telecom wavelength from Er ions, forming an effective array with over 5000 centers.

Phase diagram of spatiotemporal instabilities in a large magneto-optical trap

Large clouds of cold atoms prepared in a magneto-optical trap are known to present spatiotemporal instabilities when the frequency of the trapping lasers is brought close to the atomic resonance. This system bears similarities with trapped plasmas where the role of the Coulomb interaction is played by the exchange of scattered photons, and astrophysical objects such as stars whose size is dependent on radiative forces. We present in this paper a study of the phase-space of such instabilities, and reveal different dynamical regimes. Three dimensional simulations of the highly nonlinear atomic dynamics permit a detailed analysis of the experimental observations.

Spectral narrowing broadens applications

Four-wave mixing near atomic resonances offers new opportunities for spectral control of extreme ultraviolet pulses.

Theoretical Reassessment and Model Validation of Some Kinetic Parameters Relevant to Si/Cl/H Systems.

The increasing demand for silicon-based materials requires the optimization of silicon deposit manufacturing processes and therefore a better understanding of the gas-phase reactivity of silicon precursors such as silicon tetrachloride (SiCl4). In the present work, hydrogen atom resonance absorption spectroscopy (H-ARAS) has been used to investigate the high-temperature reactivity of SiCl4 behind reflected shock waves at ∼1.5 atm in the presence of either ethyl iodide or molecular hydrogen, used as H atom precursors. Several key reactions of SiCl4 and its main gas-phase decomposition products (SiCl3, Cl, SiHCl3, SiHCl2) have been determined theoretically. The structures and vibrational frequencies of reactants, products, and tight transition states were determined at the B2PLYP-D3/aug-cc-pVTZ level and final single-point energies refined from extrapolated RCCSD(T)/aug-cc-pVnZ (n = D, T, and Q) calculations. The minimum-energy paths of barrierless reactions were calculated at the NEVPT2 level. Final rate constants were then derived from the transition-state theory (TST) and the variational TST/master equation analysis within the rigid rotor harmonic oscillation framework. A kinetic mechanism was assembled, based on the present ab initio calculations, to successfully model and interpret the experimental absorption profiles. Sensitivity analysis unambiguously highlighted the need to account for pressure dependence in the SiCl4 decomposition (SiCl4 ⇄ SiCl3 + Cl) while discarding previous theoretical and experimental determinations of this rate constant.

Reconstruction of atomic resonances with attosecond streaking.

Recent development of spectroscopic techniques based on attosecond radiation has given the community the right tools to study the timing of the photoelectron process. In this work we investigate the effect of Fano resonances in attosecond streaking spectrograms and the application of standard phase-reconstruction algorithms. We show that while the existence of the infrared coupling (ac-Stark shift) hinders the applicability of FROG-like methods, under certain conditions it is still possible to use standard reconstruction algorithms to retrieve the photoemission delay of the bare resonance. Finally, we propose two strategies to study the strength of IR coupling using the attosecond streaking technique.

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.

Maximum Refractive Index of an Atomic Medium

It is interesting to observe that all optical materials with a positive refractive index have a value of index that is of order unity. Surprisingly, though, a deep understanding of the mechanisms that lead to this universal behavior seems to be lacking. Moreover, this observation is difficult to reconcile with the fact that a single, isolated atom is known to have a giant optical response, as characterized by a resonant scattering cross section that far exceeds its physical size. Here, we theoretically and numerically investigate the evolution of the optical properties of an ensemble of ideal atoms as a function of density, starting from the dilute gas limit, including the effects of multiple scattering and near-field interactions. Interestingly, despite the giant response of an isolated atom, we find that the maximum index does not indefinitely grow with increasing density, but rather reaches a limiting value $n\approx 1.7$. We propose an explanation based upon strong-disorder renormalization group theory, in which the near-field interaction combined with random atomic positions results in an inhomogeneous broadening of atomic resonance frequencies. This mechanism ensures that regardless of the physical atomic density, light at any given frequency only interacts with at most a few near-resonant atoms per cubic wavelength, thus limiting the maximum index attainable. Our work is a promising first step to understand the limits of refractive index from a bottom-up, atomic physics perspective, and also introduces renormalization group as a powerful tool to understand the generally complex problem of multiple scattering of light overall.

Characterizing the temperature dependence of Fano-Feshbach resonances of ultracold polarized thulium

Recent studies demonstrated anomalous temperature shifts for some Fano-Feshbach resonances of thulium atoms. These anomalies were explained by the variation in light intensity in the optical dipole trap, which accompanied changes in temperature. In addition, a temperature-related transformation of the statistics of the inter-resonance spacing was demonstrated [Aikawa et al., Phys. Rev. Lett. 108, 210401 (2012)]. Here, we analyze the shifts of isolated $s$- and $d$-type Fano-Feshbach resonances of ultracold thulium atoms with temperature for a fixed depth of an optical dipole trap. The measurements are consistent with the three-body recombination-based theory of the temperature-related resonance shift and enable the extraction of the resonance parameters, particularly the magnetic moments of closed channel states. This parameter and the known polarizability of the open channel enable us to separate the contributions of the temperature and Stark shift to the overall shift of the resonances and show the dominant role of the Stark effect in the overall shift.

Optimal design and validation of atom trapping and atomic storage time for active hydrogen maser.

From microwave atomic clocks to light clocks, atomic or ionic clocks often rely on atom or ion trapping or manipulation technology. Trapping hydrogen (H) atoms in atomic storage bulbs (ASBs) is one of the key technologies of H atomic clocks. H atoms remain in an ASB for some time during which they undergo several relaxation processes (including spin-exchange collision relaxation, atom-wall collision relaxation, and magnetic-field inhomogeneity relaxation) and interact with the electromagnetic field within the resonant cavity in the TE011 mode, giving rise to continuous atomic transitions and self-oscillations. In this study, an optimal atomic storage time Tb for a H maser was determined by optimizing various collisional relaxation times of the atomic ensemble and reducing the width of the atomic resonance line through the continuously adjustable length and radius of the opening of an ASB at various atomic beam intensities ξ (which is the number of atoms in the atomic beam), namely, 3 × 1012 atoms/s, 4 × 1012 atoms/s, and 5 × 1012 atoms/s, while keeping the structural properties and physical conditions of the H maser unchanged. For ξ = 5 × 1012 atoms/s and Tb ≈ 0.8s, a frequency stability of 0.95 × 10-15 could be achieved at 1000s.

Unstable States in a Model of Nonrelativistic Quantum Electrodynamics: Corrections to the Lorentzian Distribution

We revisit the Lee-Friedrichs model as a model of atomic resonances in the hydrogen atom, using the dipole-moment matrix-element functions which have been exactly computed by Nussenzveig. The Hamiltonian H of the model is positive and has absolutely continuous spectrum. Although the return probability amplitude \(R_{\Psi }(t) = (\Psi , \exp (-iHt) \Psi )\) of the initial state \(\Psi \), taken as the so-called Weisskopf–Wigner (W.W.) state, cannot be computed exactly, we show that it equals the sum of an exponentially decaying term and a universal correction \(O(\beta ^{2}\frac{1}{t})\), for large positive times t and small coupling constants \(\beta \), improving on some results of King (Lett Math Phys 23:215–222, 1991). The remaining, non-universal, part of the correction is also shown to be of the same qualitative type. The method consists in approximating the matrix element of the resolvent operator operator in the W.W. state by a Lorentzian distribution. No use is made of complex energies associated to analytic continuations of the resolvent operator to ”physical” Riemann sheets. Other new results are presented, in particular a physical interpretation of the corrections, and the characterization of the so-called sojourn time \(\tau _{H}(\Psi )= \int _{0}^{\infty } |R_{\Psi }(t)|^{2} dt\) as the average lifetime of the decaying state, a standard quantity in (quantum) probability.

Transient dynamics of optical-magnetic resonance in the presence of a detuned radio frequency field

The transient evolution of optical-magnetic resonance of 133Cs atoms with the action of a radio-frequency (RF) field in the presence of a static magnetic field is demonstrated theoretically and experimentally. The atomic transient absorption signal irradiated by a linearly polarized light is observed for different frequencies and intensities of RF field in our experiment. We find that both the RF frequency and intensity can modify the character of the observed signals. In particular, with an intermediate intensity, when the frequency of the RF field does not match the Larmor precession caused by the static magnetic field, a two-frequency oscillation of the transient signal can be observed. However, for the resonant case or large detuning, the transient oscillation signals go back to single frequency. Theoretical analysis based on the simplified four-level density-matrix formalism strongly supports the presented experimental data. Moreover, the density-matrix visualization analysis based on angular momentum probability surface (AMPS) explains and confirms all the features of the experimental results. These quantifiable observations enable us to reveal the atomic transient evolution more intuitively.

Confinement and edge effects on atomic collapse in graphene nanoribbons

Atomic collapse in graphene nanoribbons behaves in a fundamentally different way as compared to monolayer graphene, due to the presence of multiple energy bands and the effect of edges. For armchair nanoribbons we find that bound states gradually transform into atomic collapse states with increasing impurity charge. This is very different in zig-zag nanoribbons where multiple quasi-one-dimensional \emph{bound states} are found that originates from the zero energy zig-zag edge states. They are a consequence of the flat band and the electron distribution of these bound states exhibits two peaks. The lowest energy edge state transforms from a bound state into an atomic collapse resonance and shows a distinct relocalization from the edge to the impurity position with increasing impurity charge.

Regular and bistable steady-state superradiant phases of an atomic beam traversing an optical cavity

We investigate the different photon emission regimes created by a preexcited and collimated atomic beam passing through a single mode of an optical cavity. In the regime where the cavity degrees of freedom can be adiabatically eliminated, we find that the atoms undergo superradiant emission when the collective linewidth exceeds the transit-time broadening. We analyze the case where the atomic beam direction is slanted with respect to the cavity axis. For this situation, we find that a phase of continuous light emission similar to steady-state superradiance is established providing the tilt of the atomic beam is sufficiently small. However, if the atoms travel more than half a wavelength along the cavity axis during one transit time we predict a dynamical phase transition to a new bistable superradiant regime. In this phase the atoms undergo collective spontaneous emission with a frequency that can be either blue or red detuned from the free-space atomic resonance. We analyze the different superradiant regimes and the quantum critical crossover boundaries. In particular we find the spectrum of the emitted light and show that the linewidth exhibits features of a critical scaling close to the phase boundaries.

Surface-plasmon-based dispersive detection and spectroscopy of ultracold atoms

The paper reports on the optical detection and spectroscopy of ultracold atoms near a gold surface. A probe light field is used to excite surface plasmon polaritons. The refractive index of the atomic gas shifts the plasmon resonance and changes the reflected light power. Thus, the sensitivity of the detection is plasmonically enhanced. Absorption of photons from the evanescent wave is avoided by detuning the laser from atomic resonance which makes the detection scheme potentially nondestructive. The spectrum of the signal is determined by a Fano resonance. We show that atoms can be detected nondestructively with single atom resolution for typical parameters in cold atom experiments. Thus, the method is suitable for quantum nondemolition measurements of matter wave amplitudes. Experimentally, we measure a technically-limited sensitivity of 30 atoms and extend the detection scheme to dispersively image the atom cloud near the surface.

2-D Polarimetry of Visualized Radio Frequency Waves Using Cesium Vapor Atoms

A powerful tool for users of radio frequencies (RFs) is the ability to visualize those distributions. Here, the 2-D visualization of RF waves on a circuit board is demonstrated using the fluorescence associated with the double resonance of cesium atoms. The invisible RF waves are upconverted into near-infrared light that can be viewed with an optical camera. In addition, a 2-D visualization image is captured separately for each polarization of the RF magnetic field component using a direct-current magnetic field. The images of the 2-D polarimetry are consistent with finite-element calculations of the distribution of the magnetic field strength.