Resonance Interference Research Articles

Kondo Resonance versus Fano Interference in Double QuantumDots Coupled to a Two-Lead One-Ring System

We analyse the transport properties of a coupled double quantum dot(DQD) device with one of the dots (QD1) coupled to metallic leads andthe other (QD2) embedded in an Aharonov–Bhom (A-B) ring by means ofthe slave-boson mean-field theory. It is found that in this system, theKondo resonance and the Fano interference exist simultaneously, theenhancing Kondo effect and the increasing hopping of the QD2-Ringdestroy the localized electron state in the QD2 for the QD1-leads, andaccordingly, the Fano interference between the DQD-leads and theQD1-leads are suppressed. Under some conditions, the Fano interferencecan be quenched fully and the single Kondo resonance of the QD1-leadscomes into being. Moreover, when the magnetic flux of the A-B ring iszero, the influence of the parity of the A-B ring on the transportproperties is very weak, but this influence becomes more obvious withnon-zero magnetic flux. Thus this model may be a candidate for futuredevice applications.

Ab initiostudy of the orientation effects in multiphoton ionization and high-order harmonic generation from the ground and excited electronic states ofH2+

We present an ab initio three-dimensional (3D) calculation of multiphoton ionization (MPI) and high-order harmonic generation (HHG) of the hydrogen molecular ions subject to intense linearly polarized laser pulses. The orientation of the molecular axis with respect to the polarization of the laser field can be arbitrary. The numerical procedure involves the extension of the generalized pseudospectral (GPS) method for nonuniform spatial discretization of the Hamiltonian and wave functions and time propagation using the split-operator technique in the energy representation. The calculations were performed for the ground and two first excited electronic states of $\mathrm{H}_{2}{}^{+}$ at the internuclear separation $R=2.0\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ The laser pulse has a sine-squared envelope and contains 20 optical cycles with the wavelength $800\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. The dependence of MPI and HHG on the orientation angle is analyzed. We show that orientation effects are strongly affected by the symmetry of the wave function and the corresponding distribution of the electron density. While the anisotropy of MPI and HHG is rather weak for the $1{\ensuremath{\sigma}}_{g}$ state, both processes are suppressed at the orientation angle 90\ifmmode^\circ\else\textdegree\fi{} for the $1{\ensuremath{\sigma}}_{u}$ state and at the angle 0\ifmmode^\circ\else\textdegree\fi{} for the $1{\ensuremath{\pi}}_{u}$ state. We discuss the multiphoton resonance and two-center interference effects in the HHG spectra which can lead both to enhancement and suppression of the harmonic generation.

Highly efficient four-wave mixing in a coherent six-level system in ultraslow propagation regime

We propose a scheme to obtain a highly efficient four-wave mixing (FWM) in a coherent six-level tripod system by using a double-dark resonance and multiphoton destructive interference induced transparency. We show both analytically and numerically that the optical-wave mixing in such a system with a pump wave and an internally generated FWM wave mediated by electromagnetically induced transparency and hence propagating with matched ultraslow group velocities can result in a significant enhancement of FWM conversion efficiency. This interesting scheme may be used to generate coherent short-wavelength radiation in dense optical media with very low pump-wave intensity.

Lifetime vibrational interference during the NO 1s-1π* resonant excitation studied by the NO+(A 1Π → X 1Σ+) fluorescence

Dispersed fluorescence from fragments formed after the de-excitation of the 1s-1π* resonances of N*O and NO* has been measured in the spectral range of 118–142 nm. This range is dominated by lines of atomic nitrogen and oxygen fragments and by the \(A ~^{1}{\rm \Pi} \left(v^{\prime}\right) \rightarrow X ~^{1}{\rm \Sigma}^{+}\left(v^{\prime \prime}\right)\) bands in the NO+ ion which result from the participator Auger decay of the 1s-1π* resonances. Ab-initio calculations of the transition probabilities between vibrational levels during the reaction NO \(X~^{2}{\rm \Pi}\left(v_{0}=0\right) \rightarrow \) N*O\(\left( {\rm NO}^{\ast}\right) \) \(1s^{-1}\pi ^{\ast }\left( v_{r}\right) \) ⇒ NO\(^{+}~A~^{1}{\rm \Pi} \left(v^{\prime}\right) \rightarrow X~^{1}{\rm \Sigma}^{+}\left(v^{\prime \prime}\right)\) were used to explain the observed intensity dependence for the \(A\left(v^{\prime }\right) \rightarrow X\left(v^{\prime \prime}\right)\) fluorescence bands on the exciting-photon energy across the resonances and on both v′ and v′′ vibrational quantum numbers. The multiplet structure of the 1s-1π* resonance and lifetime vibrational interference explain the observed exciting-photon energy dependence of the \(A\left( v^{\prime}\right) \rightarrow X\left(v^{\prime \prime}\right)\) fluorescence intensity. A strong spin-orbit coupling between singlet and triplet states of NO+ is proposed to reduce additional cascade population of the \(A~^{1}{\rm \Pi}\) state via radiative transitions from the \(W~^{1}{\rm \Delta}\) and \(A^{\prime}~^{1}{\rm \Sigma}^{-}\) states and to explain remaining differences between measured and calculated integral fluorescence intensities.

Inhomogeneous electronic states in organic metal(BEDO-TTF)2ReO4·H2O: EPR and SQUID study

It is shown by electron paramagnetic resonance (EPR) and superconductingquantum interference device (SQUID) magnetometry that two spinsystems coexist in conducting layers of the quasi-2D organic metal(BEDO-TTF)2ReO4·H2O: delocalized moments of charge carriers (holes),Iepr(300 K) = 1.62 × 10−4 emu mol−1, and localizedmoments on BEDO-TTF+1, χp(300 K) = 4.25 × 10−4 emu mol−1. The phasetransition Me–Me′ at Tc = 203 K is detected in paramagnetic relaxation, EPR amplitude and resistivity. Magnetic susceptibilities,Iepr and χp, are not sensitive to the transition. Due to fine rearrangement ofReO4 linkedby H2O, the electronic spectrum becomes inhomogeneous. Below the transition exchange-coupledlocalized states within the metallic phase are observed. On cooling, the concentration ofdelocalized moments gradually decreases, contributing to a localized spin system. Thephenomenon is interpreted in terms of short-range antiferromagnetic (AFM) interactionsvia conducting electrons. Below 14 K the AFM coupled states decay, and paramagnetism oflocal moments is recovered.

Three-Body Recombination in Atoms with Large Scattering Length

Atoms with a large scattering a have universal propertes that are insensitive to short-distance details. The universal predictions for the 3-body recombination rate are known at threshold, where they depend on a and a 3-body parameter, and in the high energy scaling limit, where they depend only on the collision energy. The universal results at threshold are particularly remarkable, exhibiting resonance peaks and interference minima. They played a significant role in recent experimental evidence for Efimov physics.

Depth profiling of boron using gamma rays from the 11B(p, γ)12C reaction

The gamma ray yield of the 11B(p,γ)12C resonance reaction at 163keV was applied to depth profiling. This reaction is capable of providing boron concentration versus depth up to more than 1μm in conductive and non-conductive films. To avoid the interferences of reactions of lighter elements, the gamma ray of 11.68MeV was selected for profiling. Using a numerical method, the interference of the higher resonances was subtracted. Comparison data from the 11B(p,α)2α reaction was taken for completeness. Additionally, the profiling capabilities of the 11B(p,γ)12C and 11B(p,α0)8Be reaction are compared.

Interference of stochastic resonances: Splitting of Kramers’ rate

We consider the escape of particles located in the middle well of a symmetric triple well potential driven sinusoidally by two forces such that the potential wells rock as in stochastic resonance and the height of the potential barrier oscillates symmetrically about a mean as in resonant activation. It has been shown that depending on their phase difference the application of these two synchronized signals may lead to a splitting of time averaged Kramers' escape rate and a preferential product distribution in a parallel chemical reaction in the steady state.

Transmission resonances through aperiodic arrays of subwavelength apertures

Resonantly enhanced light transmission through periodic subwavelength aperture arrays perforated in metallic films has generated significant interest because of potential applications in near-field microscopy, photolithography, displays, and thermal emission. The enhanced transmission was originally explained by a mechanism where surface plasmon polaritons (collective electronic excitations in the metal surface) mediate light transmission through the grating. In this picture, structural periodicity is perceived to be crucial in forming the transmission resonances. Here we demonstrate experimentally that, in contrast to the conventional view, sharp transmission resonances can be obtained from aperiodic aperture arrays. Terahertz transmission resonances are observed from several arrays in metallic films that exhibit unusual local n-fold rotational symmetries, where n = 10, 12, 18, 40 and 120. This is accomplished by using quasicrystals with long-range order, as well as a new type of 'quasicrystal approximates' in which the long-range order is somewhat relaxed. We find that strong transmission resonances also form in these aperiodic structures, at frequencies that closely match the discrete Fourier transform vectors in the aperture array structure factor. The shape of these resonances arises from Fano interference of the discrete resonances and the non-resonant transmission band continuum related to the individual holes. Our approach expands potential design parameters for aperture arrays that are aperiodic but contain discrete Fourier transform vectors, and opens new avenues for optoelectronic devices.

Realization of Fabry-Perot resonators for hard X rays using micro- and nanotechnology

An X-ray Fabry-Perot resonator has been proposed and investigated for more than three decades. The difficulty in realizing such a resonator is mainly due to the strict requirement on coherence for cavity resonance, which is governed by the energy resolution of the incident X-ray photons and the size of the resonator. With the aid of modern micro-and nanotechnology for silicon, such as X-ray lithography, miniature resonators, approximately a few micrometers or smaller, can be prepared. Together with X-ray photons of ultrahigh-energy resolution from synchrotron sources, the required conditions on coherence for cavity resonance are fulfilled. Several X-ray cavities prepared by this means are used in X-ray back-diffraction experiments, where back diffraction acts as mirror reflection for X rays. Resonance interference fringes are observed unambiguously. Attempts to use multilayered materials for cavity fabrication are discussed in relation to X-ray synchrotron experiment. Possible future applications of this X-ray resonator are also mentioned.

Interference of surface plasmon resonances causes enhanced depolarized light scattering from metal nanoparticles

We show that the strongly depolarized light scattering from noble metal particles is a result of interference of two surface plasmon resonances on the same particle. The maximum depolarization occurs between two resonances. Under favorable conditions the anisotropy of the scattering light can be much lower than what is possible for dielectric particles. This explanation is discussed in relation to earlier published experimental measurements. Comparison of experimental results with theoretical calculations provides information on the shape distribution of metallic particles in the suspension.

Crystal cavity resonance for hard x rays: A diffraction experiment

We report the details of the recent x-ray back diffraction experiments, in which interference fringes due to x-ray cavity resonance are unambiguously observed. The Fabry-P\'erot type cavities, the tested crystal devices of reflectivity $R\ensuremath{\simeq}0.5$ and finesse $F\ensuremath{\simeq}2.3$, consist of monolithic two-plate and eight-plate silicon crystals. They were prepared by using x-ray lithographic techniques. The thicknesses of the crystal plates and the gaps between the two adjacent plates are a few tens to hundreds $\ensuremath{\mu}\mathrm{m}$. The (12 4 0) back reflection and synchrotron x-radiation of energy resolution $\ensuremath{\Delta}E=0.36\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ at $14.4388\phantom{\rule{0.3em}{0ex}}\mathrm{keV}$ are employed. Interference fringes in angle- and photon-energy scans for two-plate and eight-plate cavities are shown. Considerations on the temporal and spatial coherence for observable resonance interference fringes using synchrotron x-rays are presented. The details about the accompanied simultaneous 24-beam diffraction in relation to x-ray photon energy are also described.

Implementing a conditionalzgate by a combination of resonant interaction and quantum interference

We first propose an experimental scheme to implement a two-qubit conditional $z$ gate with atoms trapped in a high-$Q$ optical cavity. The scheme is based on a combination of resonant interaction and quantum interference. Further, we show that the scheme can be directly generalized to implement an $N$-qubit conditional $z$ gate, and the interaction time required to implement scheme does not change with increasing the number of qubits. This might lead to more efficient construction of quantum circuits and quantum algorithms.

Quantum transport of electrons through a parallel-coupled triple quantum-dot molecule

In this article we study the electronic transport through a triple quantum-dot molecule parallel-coupled to leads under a magnetic field. Analytical expressions are obtained for both the conductance and total density of states for the molecule in equilibrium at zero temperature. As a result of quantum interference of resonances belonging to different channels, this configuration exhibits bound states in the continuum (BICs). We examine the broadenings of the molecular states around the conditions under which BICs occur, finding long-lived states extremely robust under variations of the magnetic flux.

Development of a Fine and Ultra-Fine Group Cell Calculation Code SLAROM-UF for Fast Reactor Analyses

A cell calculation code SLAROM-UF has been developed for fast reactor analyses to produce effective cross sections with high accuracy in practical computing time, taking full advantage of fine and ultra-fine group calculation schemes. The fine group calculation covers the whole energy range in a maximum of 900-group structure. The structure is finer above 52.5 keV with a minimum lethargy width of 0.008. The ultra-fine group calculation solves the slowing down equation below 52.5 keV to treat resonance structures directly and precisely including resonance interference effects. Effective cross sections obtained in the two calculations are combined to produce effective cross sections over the entire energy range. Calculation accuracy and improvements from conventional 70-group cell calculation results were investigated through comparisons with reference values obtained with continuous energy Monte Carlo calculations. It was confirmed that SLAROM-UF reduces the difference in k-infinity from 0.15 to 0.01% for a JOYO MK-I fuel subassembly lattice cell calculation, and from −0.21 % to less than a statistical uncertainty of the reference calculation of 0.03% for a ZPPR-10A core criticality calculation.

Variable optical reflectance of a self-supported Si grating

Variable reflectance of a self-supported Si grating mirror is reported. A grating suspended in air consisted of an array of 300nm wide, 300nm thick, and 20μm long beams. The period of the grating was varied with an electrostatic microactuator from 600to720nm. A broadband reflection in the wavelength longer than the grating period was observed, which was caused by a resonant interference of the light wave propagating along the grating similar to the guided-mode resonant gratings. Increasing the period of the grating with a microactuator, the reflection spectrum changed. The results were explained by the theoretical calculations based on rigorous coupled-wave analysis.

Atom localization via interference of dark resonances

A scheme of atom localization based on the interference of resonance of double-dark states is proposed, in which the atom interacts with a classical standing-wave field. It is found that the localization property is significantly improved due to the interaction of double-dark resonances. It is realized that the atom is localized just at the nodes of the standing-wave field with higher precision. Moreover, an improvement by a factor of 2 in the detecting probability of a single atom within the subwavelength domain can be achieved by adjusting the probe-field detuning. This scheme shows more advantages than other schemes of atom localization.

Subwavelength Focusing of Light From a Metallic Slit Surrounded by Grooves with Chirped Period

Extraordinary phenomena related to the transmission of light via metallic films with subwavelength holes and grooves are known to be due to resonant excitation and interference of surface waves. These waves make various surface structures to have optically effective responses. Further, a related study subject involves the control of light transmitted from a single hole or slit by surrounding it with diffractive structures. This paper reports on the effects of controlling light with a periodic groove structure with Fresnel-type chirping. In Fresnel-type chirping, diffracted surface waves are coherently converged into a focus, and it is designed considering the conditions of constructive interference and angular spectrum optimization under the assumption that the surface waves are composite diffracted evanescent waves with a well-defined in-plane wavenumber. The focusing ability of the chirped periodic structures is confirmed experimentally by two-beam attenuated total reflection coupling. Critical factors for achieving subwavelength foci and bounds on size of focal spots are discussed in terms of the simulation, which uses the FDTD algorithm.

Leptogenesis in the minimal supersymmetric triplet seesaw model

In the supersymmetric triplet (type-II) seesaw model, in which a single SU ( 2 ) L -triplet couples to leptons, the high-energy neutrino flavour structure can be directly determined from the low-energy neutrino data. We show that even with such a minimal triplet content, leptogenesis can be naturally accommodated thanks to the resonant interference between superpotential and soft supersymmetry breaking terms.

A multitechnique investigation of the second order NLO response of a 10,20-diphenylporphyrinato nickel(II) complex carrying a phenylethynyl based push-pull system in the 5- and 15-positions

A multitechnique investigation of the determination of the order of magnitude of the second and third order NLO response of [5-[(4-dimethylaminophenyl)ethynyl]-15-[(4-nitrophenyl)ethynyl]-10,20-diphenylporphyrinato]nickel(II) (1) is reported with the aim to produce self consistent evidence for a significant NLO response of this kind of push-pull porphyrin chromophore. The experimental multitechnique approach is based on the EFISH technique, working with a non-resonant incident wavelength of 1.907 μm, on the solvatochromic method and finally on a vibrational method, avoiding any fluorescence or resonance interference. A theoretical MNDO-TDHF evaluation of the zero-frequency quadratic and cubic hyperpolarizabilities of an ab initio optimized planar structure is also reported. The order of magnitude of the quadratic hyperpolarizability of (1) at zero frequency (β0), was found to be significantly lower than that reported for the corresponding Cu (II) or Zn (II) complexes with the same push-pull porphyrin chromophore.