15 results on '"Coulomb interaction"'
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2. Inequalities for exchange Slater integrals.
- Author
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Pain, Jean-Christophe
- Subjects
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ATOMIC spectra , *INTEGRALS , *ELECTRON configuration , *ATOMIC structure - Abstract
The variations of exchange Slater integrals with respect to their order k are not well known. While direct Slater integrals Fk are positive and decreasing when the order increases, this is not stricto sensu the case for exchange integrals Gk. However, two inequalities were published by Racah in his seminal article 'Theory of complex spectra. II'. In this article, we show that the technique used by Racah can be generalized, albeit with cumbersome calculations, to derive further relations, and provide two of them, involving respectively three and four exchange integrals. Such relations can prove useful to detect regularities in complex atomic spectra and classify energy levels. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. Using analytically-corrected semiclassical rescattering model to study Coulomb impact in spiderlike photoelectron momentum distributions.
- Author
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Fu, Guoyue, Zhang, Guizhong, Zhang, Shenghua, Shi, Wei, and Yao, Jianquan
- Abstract
We present a numerical investigation on the impact of the Coulomb interaction in the spiderlike photoelectron momentum distributions (PMDs) of a hydrogen atom ionized by an intense laser pulse. We have shown, by integrating analytical correction terms into the standard semiclassical rescattering model (SRM) to formulate the Coulomb analytically-corrected SRM (AC-SRM), that the interference fringes manifest a systematic shift along the transverse momentum direction upon considering the Coulomb action. A Coulomb correction to the SRM model has rarely been reported before. Analyses are made by varying physical quantities such as the carrier frequency and initial transverse velocity of the ionized electron. In particular, we decipher the impact of the Coulomb interaction with the classical-action phase map scheme, and demonstrate that this effect is more pronounced for smaller momenta in the spiderlike PMDs. It is proven that the presented AC-SRM is simple and effective in accounting for the Coulomb effect, as an alternative correction due to the Coulomb interaction to the standard SRM theory. Also, our phase map scheme is shown to be more powerful than the plain interference fringes in interrogating the Coulomb effect, especially for the first interference minimum. We anticipate that the present AC-SRM can be useful in investigating other strong field processes where the Coulomb interaction is considered. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Two-electron conduction band of a graphene quantum dot and coherent spin manipulation
- Author
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Wen-Jun Xu, Rui-Jiang Liu, and Qing-Rui Dong
- Subjects
graphene quantum dot ,two-electron conduction ,Coulomb interaction ,Rashba spin-orbit interaction ,spin qubit ,Science ,Physics ,QC1-999 - Abstract
To get a carbon-based qubit, we pay attention to the two-electron conduction band of a graphene quantum dot (GQD) in the presence of an external magnetic field and an extrinsic Rashba spin-orbit interaction (SOI). To help understand the formation of the two-electron spectra, we first calculate the tight-binding (TB) spectra. There exist the sensitivity of the conduction band to magnetic fields and the mixing of spin states induced by a Rashba SOI. The two factors inspire the study of the magnetic-field modulation of the conduction band for realizing a spin qubit. We present the method for calculating the electronic structure of a few-electron GQD. The roles of the Coulomb interaction and the Rashba SOI in the two-electron conduction band are investigated. The Coulomb interaction contributes to a singlet-triplet level crossing and the Rashba SOI leads to a singlet-triplet mixing. The fast initialization and coherent manipulation of spin states are demonstrated by the magnetic control of singlet-triplet splitting.
- Published
- 2024
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5. Enhancing stationary entanglement between two optomechanical oscillators by Coulomb interaction with Kerr medium Project supported by the National Natural Science Foundation of China (Grant No. 11704051).
- Author
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Yang, Tian-Le, Zhu, Chen-Long, Liu, Sheng, and Xu, Ye-Jun
- Subjects
- *
COULOMB blockade , *GRANTS (Money) , *PHOTONS - Abstract
We theoretically study the stationary entanglement of two charged nanomechanical oscillators coupling via Coulomb interaction in an optomechanical system with an additional Kerr medium. We show that the degree of entanglementbetween two nanomechanical oscillators is suppressed by Kerr interaction dueto photon blockade and enhanced by Coulomb coupling strength. We also show other parameters for adjusting and obtaining entanglement, such as the driving power and the frequencies of the two oscillators, and the entanglement is robust against temperature. Our study proves a way for adjusting stationary entanglement between two optomechanical oscillators by Coulomb interaction and Kerr medium. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Ion-mediated desorption of asphaltene molecules from carbonate and sandstone structures
- Author
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Pouyan Ahmadi, Mohammadreza Aghajanzadeh, Hamidreza Asaadian, Armin Khadivi, and Shahin Kord
- Subjects
Wettability state ,Molecular dynamic simulation ,Asphaltene precipitation ,Smart water ,Bonding and non-bonding energy ,Coulomb interaction ,Materials of engineering and construction. Mechanics of materials ,TA401-492 ,Chemical technology ,TP1-1185 - Abstract
As more and more oil recovery scenarios use seawater, the need to identify the possible mechanisms of wettability state changes in oil reservoirs has never been greater. By using molecular dynamics simulations, this study sheds light on the effect of ions common to seawater (Ca ^2+ , K ^+ , Mg ^2+ , Na ^+ , Cl ^− , HCO ^3− , SO _4 ^2− ) on the affinity between silica and carbonate as the traditional rock types and asphaltene molecules as an important contributing factor of reservoir oil wetness. In the case of carbonate and silica being the reservoir rock types, the measured parameters indicate good agreement with each other, meaning that (HCO _3 ^− & SO _4 ^2− ) and (Na ^+ & Cl ^− ) ions reached maximum bonding energies of (25485, 25511, 4096, and −4093 eV, respectively). As with the surface charge density measurements, the results of the non-bonding energies between the individual atomic structures agree with those from the simulation cell. In the presence of a silica surface, the radial distribution function (RDF) results determine that the peak of the maximum value for the distribution of the ions is 4.2. However, these values range from 3 to 6.6, suggesting that different ions perform better under the influence of carbonate rock. As these ions are distributed in the simulation box along with the adsorption domain, the conditions for sequestering asphaltene from the rock surface are made ideal for dissolution and removal. At equal ion strength, measuring the distance between the center of mass of rocks and asphaltene structures reveals a maximum repulsion force of 22.1 Å and a maximum detachment force of 10.4 Å in the presence of SO _4 ^2− and Na ^+ ions on carbonate and silica surfaces.
- Published
- 2022
- Full Text
- View/download PDF
7. Theoretical studies of the THz compression of low-to-medium energy electron pulses and the single-shot stamping of electron–THz timing jitter
- Author
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Yingpeng Qi, Lele Yang, Luye Yue, Jingjun Li, Xuan Wang, Zhenrong Sun, and Jianming Cao
- Subjects
low energy electron diffraction ,electron–THz timing jitter ,Coulomb interaction ,attosecond temporal resolution ,THz compression ,Science ,Physics ,QC1-999 - Abstract
The recent development of optical control of electron pulses brings new opportunities and methodologies in the fields of light–electron interaction and ultrafast electron diffraction (UED)/microscopy. Here, by a comprehensive theoretical study, we present a scheme to compress the longitudinal duration of low (⩽1 keV) to medium energy (1–70 keV) electron pulses by the electric field of a THz wave, together with a novel shot-by-shot jitter correction approach by using the magnetic field from the same wave. Our theoretical simulations suggest the compression of the electron pulse duration to a few femtoseconds and even sub-femtosecond. A comprehensive analysis based on typical UED patterns indicates a sub-femtosecond precision of the jitter correction approach. We stress that the energy independence of Coulomb interaction in the compression and the compact structure of THz device lay the foundation of the compression of low energy electron pulses. The combination of the THz compression of the electron pulse and the electron–THz jitter correction opens a way to improve the overall temporal resolution to attosecond for ultrafast electron probes with low to medium energies and high charge number per pulse, and therefore, it will boost the ultrafast detection of transient structural dynamics in surface science and atomically thin film systems.
- Published
- 2021
- Full Text
- View/download PDF
8. Two-bands Ising superconductivity from Coulomb interactions in monolayer NbSe2
- Author
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Hörhold, Sebastian, Graf, Juliane, Marganska, Magdalena, and Grifoni, Milena
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Superconductivity ,Mechanical Engineering ,ddc:530 ,superconductivity ,TMDC ,Coulomb interaction ,BCS ,FOS: Physical sciences ,General Chemistry ,Condensed Matter Physics ,530 Physik ,Superconductivity (cond-mat.supr-con) ,Mechanics of Materials ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,General Materials Science - Abstract
The nature of superconductivity in monolayer transition metal dichalcogenides is still an object of debate. It has already been argued that repulsive Coulomb interactions, combined with the disjoint Fermi surfaces around the $K$, $K'$ valleys and at the $\Gamma$ point, can lead to superconducting instabilities in monolayer NbSe$_2$. Here, we demonstrate the two bands nature of superconductivity in NbSe$_2$. It arises from the competition of repulsive long range intravalley and short range intervalley interactions together with Ising spin-orbit coupling. The two distinct superconducting gaps, one for each spin-orbit split band, consist of a mixture of s-wave and f-wave components. Their different amplitudes are due to different normal densities of states of the two bands at the Fermi level. Using a microscopic multiband BCS approach, we derive and self-consistently solve the gap equation, demonstrating the stability of nontrivial solutions in a realistic parameter range. We find a universal behavior of the temperature dependence of the gaps and of the critical in-plane field which is consistent with various sets of existing experimental data., Comment: 19 pages, 7 figures
- Published
- 2023
9. Dynamical suppression of Coulomb interaction and sub-fs jitter correction in electron pulse compression
- Author
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Yingpeng Qi, Yan Yang, Haitao Sun, Xuan Wang, Jianming Cao, Ralph Ernstorfer, and Zhenrong Sun
- Subjects
ultrafast electron diffraction ,Coulomb interaction ,jitter correction ,electron pulse compression ,Science ,Physics ,QC1-999 - Abstract
Achieving a few-femtosecond (fs) temporal resolution in electron diffraction and electron microscopy is essential for directly tracking the electronic processes and the fastest atomic motions in molecule and condensed matter systems. The intrinsic Coulomb interaction among electrons broadens the pulse duration and restricts the temporal resolution. To tackle this issue, the electron pulse compression by the time-varying electric fields at optical, THz and RF wavelengths has been demonstrated recently. However, the Coulomb interaction still exists in the compression process and the impact of the Coulomb interaction to the compression remains largely unaccounted for. In this work, we quantify the impact of the Coulomb interaction and present three intrinsic characters of Coulomb interaction in the compression process: the Coulomb interaction is dynamically suppressed as the compression field strength rises; the electron pulse with arbitrary kinetic energy (eV to MeV) suffers the same amount of Coulomb interaction, i.e. the Coulomb interaction is independent on the kinetic energy in compression; the dynamical suppression of Coulomb interaction within a single pulse gives rise to a dispersion of the temporal focus and impedes the further compression to attosecond. Potential applications based on the revealed characters of the Coulomb interaction in the compression process are discussed. Based on the dynamical evolution of the Coulomb interaction, three stages are identified to describe the compression process, which is beyond the ballistic compression model. Additionally, a robust and noninvasive jitter correction approach matching well with the compression regime is presented and the proof-of-principle experiment demonstrates a sub-fs accuracy.
- Published
- 2020
- Full Text
- View/download PDF
10. Coulomb interaction-induced jitter amplification in RF-compressed high-brightness electron source ultrafast electron diffraction
- Author
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Yingpeng Qi, Minjie Pei, Dalong Qi, Jing Li, Yan Yang, Tianqing Jia, Shian Zhang, and Zhenrong Sun
- Subjects
ultrafast electron diffraction ,high-brightness electron source ,RF compression ,Coulomb interaction ,jitter amplification ,system optimization ,Science ,Physics ,QC1-999 - Abstract
We have theoretically and experimentally demonstrated an RF compression-based jitter-amplification effect in high-brightness electron source ultrafast electron diffraction (UED), which degrades the temporal resolution significantly. A detailed analysis and simulations reveal the crucial role of the longitudinal and transverse Coulomb interaction for this jitter-amplification effect, which accord very well with experimental results. An optimized compact UED structure for full compression has been proposed, which can suppress the jitter by half and improve the temporal resolution to sub-100 fs. This Coulomb interaction-induced jitter amplification exists in nearly the whole ultrafast physics field where laser-electron synchronization is required. Moreover, it cannot be suppressed completely. The quantified explanation for the mechanism and optimization provides important guidance for photocathode accelerators and other compression-based ultrashort electron pulse generation and precise control.
- Published
- 2017
- Full Text
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11. Thermal gating of charge currents with Coulomb coupled quantum dots
- Author
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H Thierschmann, F Arnold, M Mittermüller, L Maier, C Heyn, W Hansen, H Buhmann, and L W Molenkamp
- Subjects
quantum dot systems ,Coulomb interaction ,thermoelectrics ,thermal gating ,three-terminal device ,73.23.Hk ,Science ,Physics ,QC1-999 - Abstract
We have observed thermal gating, i.e. electrostatic gating induced by hot electrons. The effect occurs in a device consisting of two capacitively coupled quantum dots. The double dot system is coupled to a hot electron reservoir on one side (QD1), while the conductance of the second dot (QD2) is monitored. When a bias across QD2 is applied we observe a current which is strongly dependent on the temperature of the heat reservoir. This current can be either enhanced or suppressed, depending on the relative energetic alignment of the QD levels. Thus, the system can be used to control a charge current by hot electrons.
- Published
- 2015
- Full Text
- View/download PDF
12. A gauge invariant theory for time dependent heat current
- Author
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Jian Chen, Minhui ShangGuan, and Jian Wang
- Subjects
heat current ,nano capacitor ,Coulomb interaction ,Science ,Physics ,QC1-999 - Abstract
In this work, we develop a general gauge-invariant theory for AC heat current through multi-probe systems. Using the non-equilibrium Green’s function, a general expression for time-dependent electrothermal admittance is obtained where we include the internal potential due to the Coulomb interaction explicitly. We show that the gauge-invariant condition is satisfied for heat current if the self-consistent Coulomb interaction is considered. It is known that the Onsager relation holds for dynamic charge conductance. We show in this work that the Onsager relation for electrothermal admittance is violated, except for a special case of a quantum dot system with a single energy level. We apply our theory to a nano capacitor where the Coulomb interaction plays an essential role. We find that, to the first order in frequency, the heat current is related to the electrochemical capacitance as well as the phase accumulated in the scattering event.
- Published
- 2015
- Full Text
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13. Signature of symmetry of laterally coupled quantum dots in far-infrared spectrum.
- Author
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Gu Li-Ying, Li Yan-Fang, Chu Wei-Dong, and Wei Ying-Hui
- Subjects
- *
SYMMETRY (Physics) , *QUANTUM dots , *INFRARED spectroscopy , *SUPERPOSITION principle (Physics) , *COHERENCE (Physics) , *MAGNETIC fields , *COULOMB functions , *ELECTRONIC structure - Abstract
We study the effect of structure asymmetry on the energy spectrum and the far-infrared spectrum (FIR) of a lateral coupled quantum dot. The calculated spectrum shows that the parity break of coupled quantum dot results in more coherent superpositions in the low-lying states and exhibits unique anti-crossing in the two-electron FIR spectrum modulated by a magnetic field. We also find that the Coulomb correlation effect can make the FIR spectrum of coupled quantum dot without strict parity deviate greatly from Kohn theorem, which is just contrary to the symmetric case. Our results therefore suggest that FIR spectrum may be used to determine the symmetry of coupled quantum dot and to evaluate the degree of Coulomb interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
14. Charge fluctuations in open chaotic cavities
- Author
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M. L. Polianski and Markus Büttiker
- Subjects
Relaxation ,Dissipative system ,Dephasing ,FOS: Physical sciences ,General Physics and Astronomy ,ddc:500.2 ,Quantum effect ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Coulomb ,Fluctuations ,Mathematical Physics ,Physics ,Mesoscopic physics ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed matter physics ,Quantum dots ,Operator (physics) ,Shot noise ,Statistical and Nonlinear Physics ,Charge (physics) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Electric potential ,Coulomb interaction ,Mesoscopic systems ,Qubit ,Screening ,Operator ,Scattering matrix ,Time delay - Abstract
We present a discussion of the charge response and the charge fluctuations of mesoscopic chaotic cavities in terms of a generalized Wigner-Smith matrix. The Wigner-Smith matrix is well known in investigations of time-delay of quantum scattering. It is expressed in terms of the scattering matrix and its derivatives with energy. We consider a similar matrix but instead of an energy derivative we investigate the derivative with regard to the electric potential. The resulting matrix is then the operator of charge. If this charge operator is combined with a self-consistent treatment of Coulomb interaction, the charge operator determines the capacitance of the system, the non-dissipative ac-linear response, the RC-time with a novel charge relaxation resistance, and in the presence of transport a resistance that governs the displacement currents induced into a nearby conductor. In particular these capacitances and resistances determine the relaxation rate and dephasing rate of a nearby qubit (a double quantum dot). We discuss the role of screening of mesoscopic chaotic detectors. Coulomb interaction effects in quantum pumping and in photon assisted electron-hole shot noise are treated similarly. For the latter we present novel results for chaotic cavities with non-ideal leads., Comment: 29 pages, 13 figures;v.2--minor changes; contribution for the special issue of J. Phys. A on "Trends in Quantum Chaotic Scattering"
- Published
- 2005
15. Effect of the Coulomb interaction on the Peierls gap
- Author
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Eduard Tutiš and Slaven Barišić
- Subjects
Physics ,Condensed matter physics ,General Engineering ,General Physics and Astronomy ,Fermion ,Electron ,Peiels instability ,long-range ,Coulomb interaction ,gap ,Condensed Matter Physics ,Omega ,Coulomb's law ,symbols.namesake ,Quantum mechanics ,Lattice (order) ,symbols ,Coulomb ,Hamiltonian (quantum mechanics) ,Excitation - Abstract
The system of conducting electrons which interact through the long-range Coulomb force which in addition are coupled to the 2kF deformed lattice is considered within the generalised Tomonaga model for spinless fermions. The T=0 gap Delta L in the electron spectrum is evaluated using the self-consistent harmonic approximation for the excitation spectrum of the bosonised Hamiltonian. The resulting plasmons characterised by the maximum frequency omega 0, acquire the gap Delta L at T=0. The screening picture which is metallic for T>or=TLMF becomes semiconducting at T=0. However, to the leading order in Delta L/ omega 0 both TLMF and Delta L are given by the expressions involving only the short-range part of Coulomb forces, i.e. the law of corresponding states Delta L approximately=TLMF of the short-range theory is recovered.
- Published
- 1986
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