Hanbury Brown-Twiss correlations and noise in the charge transfer statistics through a multiterminal Kondo dot

We analyze the charge transfer statistics through a quantum dot in the Kondo regime, when coupled to an arbitrary number of terminals N. Special attention is paid to current cross correlations between concurring transport channels, which show distinct Hanbury Brown-Twiss antibunching for N>2 reflecting the fermionic nature of charge carriers. While this effect weakens as one moves away from the Kondo fixed point, a new type of correlations between nonconcurring channels emerges which are due entirely to the virtual polarization of the Kondo singlet. As these are not obscured by the background from fixed-point correlations they provide a promising means for extracting information on the parameters of the underlying Fermi-liquid model from the experimental data.     

Many-electron Coulomb correlations in hopping transport along layers of quantum dots

Experimental data are analyzed on the hopping transport of holes in two-dimensional layers of Ge/Si(001) quantum dots (QDs) under conditions of the long-range Coulomb interaction of charge carriers localized in QDs, when the temperature dependence of the conductivity obeys the Efros-Shklovskii law. It is found that the parameters of hopping conduction significantly deviate from the predictions of the model of one-electron excitations in “Coulomb glasses.” Many-particle Coulomb correlations associated with the motion of holes localized in QDs play a decisive role in the processes of hopping charge transfer between QDs. These correlations lead to a substantial decrease in the Coulomb barriers for the tunneling of charge carriers.     

Time‐dependent simulation of ion stopping: Charge transfer and electronic excitations

The energy loss of charged particles in matter has been studied for many decades, both, analytically and via computer simulations. While the regime of high projectile energies is well understood, low energy stopping in solids is more challenging due to the importance of non‐adiabatic effects and electronic correlations. Here we consider two problems: the charge transfer between substrate and projectile and the role of electronic correlations, specifically formation of doubly occupied lattice sites in the material during the stopping process. The former problem is treated by time‐dependent density functional theory simulations and the latter by non‐equilibrium Green functions.     

Orbital-occupancy versus charge ordering and the strength of electron correlations in electron-doped CaMnO3

The structural, electronic, and magnetic properties of mixed-valence compounds are believed to be governed by strong electron correlations. Here we report benchmark density-functional calculations in the spin-polarized generalized-gradient approximation (GGA) for the ground-state properties of doped CaMnO(3). We find excellent agreement with all available data, while inclusion of strong correlations in the GGA+U scheme impairs this agreement. We demonstrate that formal oxidation states reflect only orbital occupancies, not charge transfer, and resolve outstanding controversies about charge ordering.     

Cluster models against new and old experimental data on multiparticle production

We analyze in the cluster model framework not only recent data on zones, rapidity gap distributions and charge transfer correlations in multiparticle production, but also data on “older” quantities, in particular on inclusive and semi-inclusive longitudinal correlations. We show that a global analysis of experimental results strongly constrains the cluster characteristics. High intracluster multiplicities are definitely excluded while about 50 to 60% of clusters have to carry an electric charge; these conclusions show that well-known mesonic resonance production may indeed account for a large part of clustering.     

Evidences of a double resonant ionization mechanism in sputtering of metals

We present a theory of resonant charge exchanges, between sputtered atoms and metal surfaces, in which surface effects occur as quasi-molecular correlations in the diatomic systems formed, in the collision cascade, between secondary emitted atoms and their nearest-neighbor substrate atoms that have provided the last impulse for ejection. We set up a generalized Anderson-Newns Hamiltonian, from first principles, using a truncated and orthonormal set of states obtained from the valence orbitals of the diatomic system and from a continuous basis of jellium wave functions. We calculate the one-electron matrix elements appearing in the equations of motion for the annihilation operators of the truncated set in comparison with those resulting from the basic theory of resonant charge transfer. We determine the ionization probability of secondary emitted atoms versus their final emission velocities and we find it to be in good agreement with experimentally derived data on the Cu⁺/Cu-system. We support the hypothesis that the bare Anderson-Newns hopping mechanism needs to be completed with another charge transfer channel at the low energies of secondary ion emission.     

Strong local electron correlations in high-temperature superconductors: Mean-field description of the metal-insulator transition

A realistic model of a Cu?O-plane, as the important structural element of high-temperature superconductors, is discussed with emphasis on strong local electron correlations. The Coulomb repulsion of electrons on oxygen sites as well as the one on copper sites is assumed very large, so that a systematic approximation scheme can be based on canonical transformations for elimination of both of these interactions. The resulting multiplet-J-model encorporates correlated hopping as leading processes and interactions between local spins as next leading ones. Here we concentrate on the leading terms and study transitions between a metallic phase and a charge transfer insulator phase via bosonization and mean field theory. The full selfconsistent one particle spectra are derived for the metal and the doped charge transfer insulator. Near the phase transition an analytic solution is given. Numerical calculations are based on realistic tight binding bands and include the influence of van Hove singularities. Physical implications, some formal aspects of mean-field theory and the connection to other approaches a are discussed.     

钻石中硼受主电荷转移引发磷光的直接证据

受主元素硼与不带电荷的替位硼进行电荷重组会导致钻石发出磷光,但Ⅱb型钻石硼含量较高,难以为电荷重组与磷光的相关性提供直接证据。作者针对一粒在常光环境下近无色的钻石,利用DiamondViewTM的深紫外强光源照射样品,使之产生蓝绿色磷光,结合前人研究,推断该类型磷光与含硼元素有关。采集样品红外光谱,在磷光消退前,谱图呈现2 803 cm-1吸收峰,磷光消失后采集的红外谱图不显示2 803 cm-1峰。这一实验中受主硼在紫外光激发下失去电子,成为不带电荷的替位硼原子(B0),B0浓度升高超过红外光谱检测限,红外光谱识别到B0的存在,即引发2 803 cm-1吸收峰。处于激发态的电子返回基态与亚稳态的B0结合过程释放出光子产生磷光。该实验首次直接证实了硼受主与无电荷替位硼之间的电荷重组转移会引发钻石磷光。     

Effective interactions between concentration fluctuations and charge transfer in chemically ordering liquid alloys

Summary The correlations between long-wavelength fluctuations of concentration in a liquid binary alloy are determined by a balance between an elastic-strain free energy and an Ornstein-Zernike effective interaction. The latter is extracted from thermodynamic data in the case of the Li−Pb system, which is well known to chemically order with stoichiometric composition corresponding to Li₄Pb. Strong attractive interactions between concentration fluctuations near the composition of chemical ordering originate from electronic charge transfer, which is estimated from the electron-ion partial structure factors as functions of composition in the liquid alloy. In honour of Prof. Fausto Fumi on the occasion of his retirement from teaching.     

Optical Bloch equations with dual photon excitation explain the polarization dependence of four wave mixing quantum beats

We explain the polarization dependence of four wave mixing (FWM) quantum beats for semiconductors as essentially due to the spin phase correlations of photo-excited electrons, rather than to Coulomb interaction between the electrons. A theoretical analysis is given within the framework of optical Bloch equations for the light–semiconductor interactions and the Luttinger–Kohn model for the band structure. Residual Coulomb interactions between charge carriers are ignored. The results suggest that the polarization dependence of FWM quantum beats is a purely coherent effect of dual photon excitations, rather than, e.g., exciton–exciton Coulomb interaction. We show that the coherence transfer between the excited states is responsible for the FWM in a configuration with orthogonally polarized pump and probe.     

Distributions of waiting times of dynamic single-electron emitters

The distribution of waiting times between elementary tunneling events is of fundamental importance for understanding the stochastic charge transfer processes in nanoscale conductors. Here we investigate the waiting time distributions (WTDs) of periodically driven single-electron emitters and evaluate them for the specific example of a mesoscopic capacitor. We show that the WTDs provide a particularly informative characterization of periodically driven devices and we demonstrate how the WTDs allow us to reconstruct the full counting statistics (FCS) of charges that have been transferred after a large number of periods. We find that the WTDs are capable of describing short-time physics and correlations which are not accessible via the FCS alone.     

Effects of intrinsic decoherence on various correlations and quantum dense coding in a two superconducting charge qubit system

The influence of intrinsic decoherence on various correlations and dense coding in a model which consists of two identical superconducting charge qubits coupled by a fixed capacitor is investigated. The results show that, despite the intrinsic decoherence, the correlations as well as the dense coding channel capacity can be effectively increased via the combination of system parameters, i.e., the mutual coupling energy between the two charge qubits is larger than the Josephson energy of the qubit. The bigger the difference between them is, the better the effect is.     

新型电荷转移多金属氧酸盐的合成和红外光谱研究

以4种道森结构的杂多酸和3种芳香杂环化合物为原料合成了11种新型电荷转移多金属氧酸盐，研究了它们的红外光谱。结果表明：杂多酸形成电荷转移盐后，杂多阴离子的结构略有畸变但仍保持道森结构；有机给体和杂多阴离子之间存在电荷转移相互作用。     

Ferrimagnetic ground state of a phenylene polymer with organic radicals

A ferrimagnetic polymer with m-phenylene skeleton as coupling unit is studied with the Hubbard model in the self-consistent mean-field theory. The ferrimagnetic ground state with a total spin S = 1 per unit cell is obtained and originates from the antiferromagnetic correlations between the nearest neighbors. If the on-site electron-electron repulsions at the radical sites and at the phenylene ring sites are different, the gap in energy band structure may disappear and the ferrimagnetic ground state becomes unstable. The charge density and spin density can transfer between the radical sites and the phenylene ring sites due to the competition between the hopping integral and the on-site repulsion at different sites. Received 15 July 2002 Published online 31 December 2002     

Threshold formation of an intermolecular charge transfer complex of a semiconducting polymer

It has been found that the formation of an intermolecular charge transfer complex in the ground electronic state between the model conjugated polymer (poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and the low-molecular-weight organic acceptor (2,4,7-trinitrofluorenone, TNF) occurs stepwise with an increase in the acceptor concentration in the blend as is observed in the optical absorption spectra of solutions. The threshold dependence of the absorption of the charge transfer complex is attributed to the stepwise change in the concentration of the charge transfer complexes, which is not explained by the standard model describing the optical characteristics of intermolecular charge transfer complexes. A kinematic model has been proposed to explain the threshold increase in the concentration of charge transfer complexes: at low acceptor concentrations, the charge transfer complex is formed primarily on the surface of a polymer coil, whereas as the acceptor fraction in the solution increases, TNF molecules penetrate inside the polymer coils, forming the charge transfer complex with the units of the polymer inside the coil.     

Energy transfer and correlation dynamics in a three-quasi-spin-pigment system

In this paper, the effects of quantum and classical correlations on the excitation energy transfer in a three-quasi-spin-pigment system are investigated. We first study the dependence of the energy transfer efficiency on various initial correlations of the donor pigments, and find that the initial concurrence is crucial to the efficiency no matter whether the initial states are pure or mixed. We then demonstrate the dynamics of correlations of the system and observe the appearance of sudden death of quantum correlations in the donor pigments. The relation between the energy transfer efficiency and the dynamics of correlations in the donor pigments is also discussed.     

Photoinduced charge transfer across the interface between organic molecular crystals and polymers

Photoinduced charge transfer of positive and negative charges across the interface between a single-crystal organic semiconductor and a polymeric insulator is observed in electric field-effect experiments. Immobilization of the transferred charge by deep traps in the polymer results in a shift of the threshold of field-induced conductivity along the semiconductor-polymer interface, which allows for direct measurements of the charge transfer rate. The transfer occurs when the photon energy exceeds the absorption edge of the semiconductor. The direction of the transverse electric field at the interface determines the sign of the transferred charge; the transfer rate is controlled by the field magnitude and light intensity.     

Enhanced charge gap in the bilayer manganite La2-2xSr1+2xMn2O7 near x = 0.4

We have investigated the optical conductivity spectra of La2-2xSr1+2xMn2O7 (0.3相似文献