Total cross sections for electron scattering from He and Ne at very low energies

Shigemura, K; Kitajima, M.; Kurokawa, M.; Toyoshima, K.; Odagiri, Takeshi; Suga, A.; Kato, H.; Hoshino, M.; Tanaka, Hiroshi; Ito, Kenji

doi:10.1103/physreva.89.022709

Cited by 19 publications

(12 citation statements)

References 56 publications

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“…Assuming that the trapped electrons have a uniform energy distribution between 0 and U depth , the average energy gain per collision with a single helium atom is smaller than U depth /4. The rate of collisions in this case is ∼ σ elastic n He |v| where σ elastic ∼ 6Å 2 is the electron-helium elastic cross section for low energy (≤ 2 eV) electrons [104] and |v| ∼…”

Section: Low Energy Electron Sourcementioning

confidence: 99%

Hybrid quantum systems with trapped charged particles

2017

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Trapped charged particles have been at the forefront of quantum information processing (QIP) for a few decades now, with deterministic two-qubit logic gates reaching record fidelities of 99.9% and single qubit operations of much higher fidelity. In a hybrid system involving trapped charges, quantum degrees of freedom of macroscopic objects such as bulk acoustic resonators, superconducting circuits or nano-mechanical membranes, couple to the trapped charges and ideally inherit the coherent properties of the charges. The hybrid system therefore implements a "quantum transducer", where the quantum reality (i.e. superpositions and entanglement) of small objects is extended to include the larger object. Although a hybrid quantum system with trapped charges could be valuable both for fundamental research and for QIP application, no such system exists today. Here we study theoretically the possibilities of coupling the quantum mechanical motion of a trapped charged particle (e.g. ion or electron) to quantum degrees of freedom of superconducting devices, nano-mechanical resonators and quartz bulk acoustic wave resonators. For each case, we estimate the coupling rate between the charged particle and its macroscopic counterpart and compare it to the decoherence rate, i.e. the rate at which quantum superposition decays. A hybrid system can only be considered quantum if the coupling rate significantly exceeds all decoherence rates. Our approach is to examine specific examples, using parameters that are experimentally attainable in the foreseeable future. We conclude that those hybrid quantum system considered involving an atomic ion are unfavorable, compared to using an electron, since the coupling rates between the charged particle and its counterpart are slower than the expected decoherence rates. A system based on trapped electrons, on the other hand, might have coupling rates which significantly exceed decoherence rates. Moreover it might have appealing properties such as fast entangling gates, long coherence and flexible electron interconnectivity topology. Realizing such a system, however, is technologically challenging, since it requires accommodating both trapping technology and superconducting circuitry in a compatible manner. We review some of the challenges involved, such as the required trap parameters, electron sources, electrical circuitry and cooling schemes in order to promote further investigations towards the realization of such a hybrid system. CONTENTS

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Section: Low Energy Electron Sourcementioning

confidence: 99%

Hybrid quantum systems with trapped charged particles

2017

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“…In the calculations, an experimental value of the dipole polarizability of neon, α = 2.571a 3 0 [40], is used. The parameters of the effective range expansions, B l and R l , have to be determined empirically by comparison with some experimental data.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Recently, Shigemura et al [3] employing threshold photo electron source were able to measure Ne total cross-sections (TCS) down to 7 meV. Linert et al [4] and Cho et al [5] using magnetic angle-changer were able to extend differential cross-section (DCS) measurements to 180 • scattering angle that was inaccessible in the past.…”

Section: Introductionmentioning

confidence: 99%

Electron Scattering from Neon Via Effective Range Theory

Fedus

2014

Braz J Phys

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Elastic cross-sections for electron scattering on neon from 0 energy up to 16 eV are analyzed by an analytical approach to the modified effective range theory (MERT). It is shown that energy and angular variations of elastic differential, integral and momentum transfer crosssections can be accurately parameterized by six MERT coefficients up to the energy threshold for the first Feshbach resonance. MERT parameters are determined empirically by numerical comparison with large collection of available experimental data of elastic total (integral) cross-sections. The present analysis is validated against numerous electron beams and swarm experiments. The comparison of derived MERT parameters with those found for other noble gases, helium, argon and krypton, is done. The derived scattering length (for the s-partial wave) in neon, 0.227a 0 , agrees well with recent theories; it is small but, differently from Ar and Kr, still positive. Analogue parameters for the p-wave and the d-wave are negative and positive respectively for all the four gases compared.

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“…Figures 2, 3, and 4 show experimental data for the electron and positron TCSs for Ne, Ar, and Xe, respectively, from threshold to 10 eV. The electron cross sections were taken from the articles of Shigemura et al [23] and Kurokawa et al [24]. For historical reasons, two sets of positron TCS's are considered.…”

Section: Total Cross Sections and The Ramsauer-townsend Effectmentioning

confidence: 99%

The Hidden Ramsauer-Townsend Effect in Positron Scattering by Rare Gas Atoms

et al. 2020

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The aim of this work is to present and discuss the Ramsauer-Townsend effect in the context of low-energy positron scattering by rare gas atoms. Opposed to what happens in electron-atom scattering, the competition between the static repulsive and polarization attractive potentials makes the phenomenon improbable in positron case. Nonetheless, we show using a semiempirical potential formulation that, while the effect is explicitly observed in the total cross sections for He and Ne, for the heavier noble gases it becomes "hidden" or implicit. We show that as the atomic polarizability increases, the suppression of s-wave goes to higher energies due to the variation of the scattering length with the polarizability. No specific signature for the effect is found in the shape of the differential cross sections but curiously, while the effect is implicit in the total cross section for Ar, it generates a minimum structure in the momentum transfer cross section. The theme is presented for non-specialist audience with emphasis in basic atomic and scattering theories along with practical results, the main objective being to boost the traditional discussions with a new view on the subject.

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Total cross sections for electron scattering from He and Ne at very low energies

Cited by 19 publications

References 56 publications

Hybrid quantum systems with trapped charged particles

Hybrid quantum systems with trapped charged particles

Electron Scattering from Neon Via Effective Range Theory

The Hidden Ramsauer-Townsend Effect in Positron Scattering by Rare Gas Atoms

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