arXiv subjects

Ginette Jalbert

Publications and source records attributed to Ginette Jalbert.

13 recordsLinked to original sources

arXiv2026

Highly correlated electronic bounding and spin effect: confirmation of an autodetaching state of O$^-$

The existence of an auto-detaching state of O$^-$ with a lifetime on the scale of a hundred nanoseconds is demonstrated both experimentally and theoretically. The O$^-$ lifetime values are determined using two recently developed methods. The experimental approach is based on a derivation from measured electron-loss cross sections combined with time-of-flight spectrometry. For the theoretical approach, the continued Green's function within the formalism of Fano-Feshbach is applied. We present the measured lifetime value of $100 \pm 10 \text{ ns}$. The calculated lifetime value is 75 ns, and is associated with the (2p$^3$3s$^2$)$^4$S state of O$^-$. We discuss how the existence of a 100-ns-lifetime oxygen metastable anion can impact the modeling of oxygen-containing systems.

physics.atom-ph↗

arXiv2024

Informational analysis of the confinement of an electron in an asymmetric double quantum dot

A quasi-unidimensional one-electron double quantum dot is studied within the framework of Shannon informational entropy. Its confinement potential, which is described by an asymmetric harmonic-gaussian function, consists of two wells separated by a potential barrier, and the asymmetry of the potential in respect to the center of the barrier is parameterized by $x_0$. In this work we employ Shannon informational entropy as a tool to investigate changes in the electronic confinement resulting from the modifications in the degree of asymmetry $x_0$. In particular, we notice that Shannon entropy turns out to be very sensitive to the change from the symmetric to the antisymmetric regime. Moreover, we show that Shannon entropy as a function of $x_0$ for an electronic excited state displays an irregular behavior whenever the state energy is in the vicinity of a local extreme (a maximum or a minimum); connected with this we observe an oscillatory behavior of the energy of the excited states as a function of $x_0$.

physics.atom-ph↗

arXiv2024

Electron Confinement study in a double quantum dot by means of Shannon Entropy Information

In this work, we use the Shannon informational entropies to study an electron confined in a double quantum dot; we mean the entropy in the space of positions, $S_r$, in the space of momentum, $S_p$, and the total entropy, $S_t = S_r+S_p$. We obtain $S_r$, $S_p$ and $S_t$ as a function of the parameters $A_2$ and $k$ which rules the height and the width, respectively, of the internal barrier of the confinement potential. We conjecture that the entropy $S_r$ maps the degeneracy of states when we vary $A_2$ and also is an indicator of the level of decoupling/coupling of the double quantum dot. We study the quantities $S_r$ and $S_p$ as measures of delocalization/localization of the probability distribution. Furthermore, we analyze the behaviors of the quantities $S_p$ and $S_t$ as a function of $A_2$ and $k$. Finally, we carried out an energy analysis and, when possible, compared our results with work published in the literature.

physics.atom-ph↗

arXiv2022

3D two-electron double quantum dot: comparison between the behavior of some physical quantities under two different confinement potentials in the presence of a magnetic field

We have considered a system consisting of two coupled quantum dots containing two electrons, i.e., two quantum dots next to each other with one excess electron each, subjected to an uniform magnetic field perpendicular to the quantum dots plane. The effect of different confinement potential profiles under which the electrons are subjected is studied. This study has been performed in the light of interest in fundamental logical quantum-gate operations: we have been concerned in analysing the behaviour of the main physical quantities which should be involved in a two-qubit quantum-gate operation for two different profiles of confinement found in literature. Our purpose was to establish how sensitive the physical quantities are to the confinement profile and in which range of magnetic field this issue can be critical.

cond-mat.mes-hall↗

arXiv2020

On the oscillating properties of a two-electron quantum dot in the presence of a magnetic field

We give a basic explanation for the oscillating properties of some physical quantities of a two-electron quantum dot in the presence of a static magnetic field. This behaviour was discussed in a previous work of ours [AM Maniero, {\it et al}. J. Phys. B: At. Mol. Opt. Phys. 53:185001, 2020] and was identified as a manifestation of the {\it de Haas-van Alphen} effect, originally observed in the framework of diamagnetism of metals in the 30's. We show that this behaviour is a consequence of different eigenstates of the system assuming, in a certain interval of the magnetic field, the condition of the lowest energy singlet and triplet states.

cond-mat.str-el↗

arXiv2020

Quantum State Preparation of Hydrogen Atoms by Hyperfine Quenching

We discuss the use of a region of uniform and constant magnetic field in order to implement a two-state atomic polarizer for an H(2S) beam. We have observed that a device with such field configuration is capable of achieving an efficient polarization for a wide range of magnetic field intensities and atomic velocities. In addition, we establish a criterion that must be met to confirm a successful polarization. That is possible due to a specific beating pattern for the Lyman-$α$ radiation expected for the outgoing two-state atomic beam.

physics.atom-ph↗

arXiv2020

Oscillating properties of a two-electron quantum dot in the presence of a magnetic field

We study the system consisted of two electrons in a quantum dot with a three-dimensional harmonic confinement potential under the effect of a magnetic field. Specifically, two different confinement conditions are considered, one isotropic three-dimensional and the other anisotropic quasi-two-dimensional. Singlet and triplet lowest states properties as the energy, the exchange coupling, the two-electron density function and the spatial spreading of the two electrons in terms of the variance along the x-direction are analysed. In this study we employ the full configuration interaction method with Cartesian anisotropic Gaussian-type orbitals as basis set. These functions allow to explore the confining characteristics of a potential due to their flexibility of using different exponents for each direction in space. The convergence of the results, depending on the size of the set of basic functions, is examined and the oscillations of different physical quantities, concerning the singlet and triplet states, as a function of the magnetic field are discussed.

cond-mat.str-el↗

arXiv2018

Effect of a laser field in the confinement potential of two electrons in a double quantum dot

We have studied a system consisted of two coupled quantum dots containing two electrons subjected by a laser field. The effect of the laser is described by the dressed-band approach involving the concept of the conduction/valence effective mass, valid far from resonance. The interaction between the electrons and the quantum dots is described by a phenomenological tridimensional potential, which simulates quantum dots in GaAs heterostructure. In this study we have employed the approach already presented in a previous work [Olavo et al., J. Phys. B: At. Mol. Opt. Phys. {\bf 49}, 145004 (2016)]. We have used a code based on the full interaction configuration method. We have employed as basis set the {\it Cartesian anisotropic Gaussian-type} orbitals which allows one to explore the confining characteristics of a potential due to their flexibility of using different exponents for each direction space. We present an analysis based on the energy levels of the singlet and triplet as function of the confinement parameters.

cond-mat.str-el↗

arXiv2018

Interference effects due to nuclear motion of the hydrogen molecule

We show that two-particle interferences can be used to probe the nuclear motion in a doubly-excited hydrogen molecule. The dissociation of molecular hydrogen by electron impact involves several decay channels, associated to different molecular rotational states, which produce quantum interferences in the detection of the atomic fragments. Thanks to the correlations between the angular momentum and vibrational states of the molecule, the fragments arising from each dissociation channel carry out a phase-shift which is a signature of the molecule rotation. These phase-shifts, which cannot be observed in a single-atom detection scheme, may be witnessed in realistic experimental conditions in a time-of-flight coincidence measurement. We analyse the interferences arising from the two lowest-energy rotational states of a para-hydrogen molecule. Our result shows the relevance of two-fragments correlations to track the molecular rotation.

physics.atom-ph↗

arXiv2015

Toward a test of angular momentum coherence in a twin-atom interferometer

We present a scheme well-suited to investigate quantitatively the angular momentum coherence of molecular fragments. Assuming that the dissociated molecule has a null total angular momentum, we investigate the propagation of the corresponding atomic fragments in the apparatus. We show that the envisioned interferometer enables one to distinguish unambiguously a spin-coherent from a spin-incoherent dissociation, as well as to estimate the purity of the angular momentum density matrix associated with the fragments. This setup, which may be seen as an atomic analogue of a twin-photon interferometer, can be used to investigate the suitability of molecule dissociation processes -- such as the metastable hydrogen atoms H($2^2 S$)-H($2^2 S$) dissociation - for coherent twin-atom optics.

quant-ph↗

arXiv2015

Potential Energy Curves and Generalized Oscillator Strength for Doubly Excited States of Hydrogen Molecule

In this paper we report calculations of potential energy curves in the $1.2 a.u.\le R\le100 a.u.$ range at Multireference Configuration Interaction (MRCI) level for doubly excited states of the H$_2$ molecule. We have focused on the $Q_2$ states which lie between the second and third ionization thresholds of H$_2^+$ molecular ion, i.e., $^2Σ_u^+$ state in which lie the H(2l) + H(2l') dissociation channels. The MRCI approach allowed us to successfully identify for the first time the molecular state which dissociates into hydrogen atoms at 2s state. Further, Generalized Oscillator Strength as a function of transferred momentum for three doubly excited states is also presented. (Some figures in this article are in colour only in the electronic version)

physics.atom-ph↗

arXiv2013

Experimental evidence of twin fast metastable H(2S) atoms from dissociation of cold H_2 induced by electrons

We report the direct detection of two metastable H(2S) atoms coming from the dissociation of a single cold H_2 molecule, in coincidence measurements. The molecular dissociation was induced by electron impact in order to avoid limitations by the selection rules governing radiative transitions. Two detectors, placed close from the collision center, measure the neutral metastable H(2S) through a localized quenching process, which mixes the H(2S) state with the H(2P), leading to a Lyman-αdetection. Our data show the accomplishment of a coincidence measurement which proves for the first time the existence of the H(2S)-H(2S) dissociation channel.

physics.atom-ph↗

arXiv2007

Nonprobabilistic teleportation of field state via cavity QED

In this article we discuss a teleportation scheme of coherent states of cavity field. The experimental realization proposed makes use of cavity quatum electrodynamics involving the interaction of Rydberg atoms with micromaser and Ramsey cavities. In our scheme the Ramsey cavities and the atoms play the role of auxiliary systems used to teleport the state from a micromaser cavity to another. We show that, even if the correct atomic detection fails in the first trials, one can succeed in teleportating the cavity field state if the proper measurement occurs in a later atom.

quant-ph↗