Luttinger liquids with curvature: Density correlations and Coulomb drag effect

We consider the effect of the curvature in fermionic dispersion on the observable properties of Luttinger liquid (LL). We use the bosonization technique where the curvature is irrelevant perturbation, describing the decay of LL bosons (plasmon modes). When possible, we establish the correspondence between the bosonization and the fermionic approach. We analyze modifications in density correlation functions due to curvature at finite temperatures, T. The most important application of our approach is the analysis of the Coulomb drag by small momentum transfer between two LL, which is only possible due to curvature. Analyzing the a.c. transconductivity in the one-dimensional drag setup, we confirm the results by Pustilnik et al. for T-dependence of drag resistivity, R_{12} ~ T^2 at high and R_{12} ~ T^5 at low temperatures. The bosonization allows for treating both intra- and inter-wire electron-electron interactions in all orders, and we calculate exact prefactors in low-T drag regime. The crossover temperature between the two regimes is T_1 ~ E_F \Delta, with \Delta relative difference in plasmon velocities. We show that \Delta \neq 0 even for identical wires, due to lifting of degeneracy by interwire interaction, U_{12}, leading to crossover from R_{12} ~ U_{12}^2 T^2 to R_{12} \~ T^5/U_{12} at T ~ U_{12}.Comment: 16 pages, 10 figures, REVTE

The mean energy, strength and width of triple giant dipole resonances

We investigate the mean energy, strength and width of the triple giant dipole resonance using sum rules.Comment: 12 page

RPAE versus RPA for the Tomonaga model with quadratic energy dispersion

Recently the damping of the collective charge (and spin) modes of interacting fermions in one spatial dimension was studied. It results from the nonlinear correction to the energy dispersion in the vicinity of the Fermi points. To investigate the damping one has to replace the random phase approximation (RPA) bare bubble by a sum of more complicated diagrams. It is shown here that a better starting point than the bare RPA is to use the (conserving) linearized time dependent Hartree-Fock equations, i.e. to perform a random phase approximation (with) exchange (RPAE) calculation. It is shown that the RPAE equation can be solved analytically for the special form of the two-body interaction often used in the Luttinger liquid framework. While (bare) RPA and RPAE agree for the case of a strictly linear disperson there are qualitative differences for the case of the usual nonrelativistic quadratic dispersion.Comment: 6 pages, 3 figures, misprints corrected; to appear in PRB7

16-channnel Micro Magnetic Flux Sensor Array for IGBT Current Distribution Measurement

Current crowding of IGBT and power diode in a chip or among chips is a barrier to the realization of highly-reliable power module and power electronics system. Current crowding occurs because of the parasitic inductance, difference of chip characteristics or temperature imbalance among chips. Although current crowding among IGBT or power diode chips has been analysed on numerical simulations, no sensor with sufficiently high special resolution and fast measurement time has yet been demonstrated. Therefore, the author developed and demonstrated 16-channel flat sensitivity sensor array for IGBT current distribution measurement. The sensor array consists of tiny-scale film sensors with analog amps and shield case against noise. The array and digital calibration method will be applied for reliability analysis, designing and screening of IGBT modules.ESREF 2015, 26th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis, Oct 5-9, 2015, Centre de Congrès Pierre Baudis, Toulouse, Franc

High-throughput and Full Automatic DBC-Module Screening Tester for High Power IGBT

We developed a high-throughput screening tester for DBC-module of IGBT. The tester realizes a new screening test with current distribution in addition to a conventional switching test. It consists of a power circuit, a replaceable test head, sensor array module and digitizer with LabVIEW program. Therefore, all kinds of DBC-modules can be screened by switching the test head. The tester acquires magnetic field signals and displays GO/NOGO judgment automatically after digital calibration and signal processing in 10 seconds. It is expected to be applied for screening in a production line and analysis in order to prevent the failure of power modules.ESREF 2015, 26th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis, Oct 5-9, 2015, Centre de Congrès Pierre Baudis, Toulouse, Franc

Infrared catastrophe and tunneling into strongly correlated electron systems: Exact solution of the x-ray edge limit for the 1D electron gas and 2D Hall fluid

In previous work we have proposed that the non-Fermi-liquid spectral properties in a variety of low-dimensional and strongly correlated electron systems are caused by the infrared catastrophe, and we used an exact functional integral representation for the interacting Green's function to map the tunneling problem onto the x-ray edge problem, plus corrections. The corrections are caused by the recoil of the tunneling particle, and, in systems where the method is applicable, are not expected to change the qualitative form of the tunneling density of states (DOS). Qualitatively correct results were obtained for the DOS of the 1D electron gas and 2D Hall fluid when the corrections to the x-ray edge limit were neglected and when the corresponding Nozieres-De Dominicis integral equations were solved by resummation of a divergent perturbation series. Here we reexamine the x-ray edge limit for these two models by solving these integral equations exactly, finding the expected modifications of the DOS exponent in the 1D case but finding no changes in the DOS of the 2D Hall fluid with short-range interaction. We also provide, for the first time, an exact solution of the Nozieres-De Dominicis equation for the 2D electron gas in the lowest Landau level.Comment: 6 pages, Revte

Correlated sequential tunneling through a double barrier for interacting one-dimensional electrons

The problem of resonant tunneling through a quantum dot weakly coupled to spinless Tomonaga-Luttinger liquids has been studied. We compute the linear conductance due to sequential tunneling processes upon employing a master equation approach. Besides the previously used lowest-order golden rule rates describing uncorrelated sequential tunneling (UST) processes, we systematically include higher-order correlated sequential tunneling (CST) diagrams within the standard Weisskopf-Wigner approximation. We provide estimates for the parameter regions where CST effects can be important. Focusing mainly on the temperature dependence of the peak conductance, we discuss the relation of these findings to previous theoretical and experimental results.Comment: replaced with the published versio

Theory of Resonant Raman Scattering in One Dimensional Electronic systems

A theory of resonant Raman scattering spectroscopy of one dimensional electronic systems is developed on the assumptions that (i) the excitations of the one dimensional electronic system are described by the Luttinger Liquid model, (ii) Raman processes involve virtual excitations from a filled valence band to an empty state of the one dimensional electronic system and (iii) excitonic interactions between the valence and conduction bands may be neglected. Closed form analytic expressions are obtained for the Raman scattering cross sections, and are evaluated analytically and numerically for scattering in the polarized channel, revealing a "double-peak" structure with the lower peak involving multispinon excitations with total spin S=0 and the higher peak being the conventional plasmon. A key feature of our results is a nontrivial power law dependence, involving the Luttinger Liquid exponents, of the dependence of the Raman cross sections on the difference of the laser frequency from resonance. We find that near resonance the calculated ratio of intensity in the lower energy feature to the intensity in the higher energy feature saturates at a value of the order of unity (times a factor of the ratio of the velocities of the two modes). We explicate the differences between the 'Luttinger liquid' and 'Fermi liquid' calculations of RRS spectra and argue that excitonic effects, neglected in all treatments so far, are essential for explaining the intensity ratios observed in quantum wires. We also discuss other Luttinger liquid features which may be observed in future RRS experiments

Quantum Scattering in Quasi-1D Cylindrical Confinement

Finite size effects alter not only the energy levels of small systems, but can also lead to new effective interactions within these systems. Here the problem of low energy quantum scattering by a spherically symmetric short range potential in the presence of a general cylindrical confinement is investigated. A Green's function formalism is developed which accounts for the full 3D nature of the scattering potential by incorporating all phase-shifts and their couplings. This quasi-1D geometry gives rise to scattering resonances and weakly localized states, whose binding energies and wavefunctions can be systematically calculated. Possible applications include e.g. impurity scattering in ballistic quasi-1D quantum wires in mesoscopic systems and in atomic matter wave guides. In the particular case of parabolic confinement, the present formalism can also be applied to pair collision processes such as two-body interactions. Weakly bound pairs and quasi-molecules induced by the confinement and having zero or higher orbital angular momentum can be predicted, such as p- and d-wave pairings.Comment: Extended version of quant-ph/050319

Peculiarities of the Weyl - Wigner - Moyal formalism for scalar charged particles

A description of scalar charged particles, based on the Feshbach-Villars formalism, is proposed. Particles are described by an object that is a Wigner function in usual coordinates and momenta and a density matrix in the charge variable. It is possible to introduce the usual Wigner function for a large class of dynamical variables. Such an approach explicitly contains a measuring device frame. From our point of view it corresponds to the Copenhagen interpretation of quantum mechanics. It is shown how physical properties of such particles depend on the definition of the coordinate operator. The evolution equation for the Wigner function of a single-charge state in the classical limit coincides with the Liouville equation. Localization peculiarities manifest themselves in specific constraints on possible initial conditions.Comment: 16 pages, 2 figure