Spectral properties of the one-dimensional two-channel Kondo lattice model

We have studied the energy spectrum of a one-dimensional Kondo lattice, where the localized magnetic moments have SU(N) symmetry and two channels of conduction electrons are present. At half filling, the system is shown to exist in two phases: one dominated by RKKY-exchange interaction effects, and the other by Kondo screening. A quantum phase transition point separates these two regimes at temperature $T = 0$. The Kondo-dominated phase is shown to possess soft modes, with spectral gaps much smaller than the Kondo temperature.Comment: 4 pages + 2 figures. Submitted for publicatio

PENGARUH KOMPETENSI, INDEPENDENSI DAN MOTIVASI TERHADAP KUALITAS PENGAWASAN KEUANGAN DI DINAS PARIWISATA PROVINSI SULAWESI UTARA

ABSTRAKPengawasan adalah suatu upaya yang sistematik untuk menetapkan kinerja standar pada perencanaan untuk merancang sistem umpan balik informasi, untuk membandingkan kinerja aktual dengan standar yang telah ditentukan, untuk menetapkan apakah telah terjadi suatu penyimpangan tersebut, serta untuk mengambil tindakan perbaikan yang diperlukan untuk menjamin bahwa semua sumber daya telah digunakan seefektif dan seefisien mungkin guna mencapai tujuan instansi pemerintah. Faktor-faktor yang mempengaruhi pengawasan keuangan daerah antara lain kompetensi, independensi dan motivasi. Tujuan penelitian ini adalah untuk mengetahui pengaruh kompetensi, independensi dan motivasi terhadap kualitas pengawasan keuangan baik secara parsial maupun simultan. .Hasil penelitian menunjukkan bahwa secara parsial Kompetensi tidak berpengaruh signifikan terhadap Kualitas Pengawasan Keuangan Pada Dinas Pariwisata Provinsi Sulut, secara parsial Independensi berpengaruh signifikan terhadap Kualitas Pengawasan Keuangan Pada Dinas Pariwisata Provinsi Sulut, secara parsial Motivasi tidak berpengaruh signifikan terhadap Kualitas Pengawasan Keuangan Pada Dinas Pariwisata Provinsi Sulut dan secara simultan Kompetensi, Independensi dan Motivasi berpengaruh signifikan terhadap Kualitas Pengawasan Keuangan Pada Dinas Pariwisata Provinsi Sulut. Kata kunci : kualitas pengawasan keuangan, kompetensi, independensi, motivasiABSTRACTSupervision is a systematic attempt in order to establish the default performance of  a predetermined plan to design feedback of information system, to compare the actual performance to the default standard, in order to know whether there has been a deviation, as well to take a repair action which needed to ensure that all the resources of the fund have been used effectively and efficiently in accomplishing government goals. Factors that may affect the regional financial supervision are Competences, Independences and Motivation. The purpose of this research is to know the influence of Competence, Independence and Motivation toward the Quality of Regional Financial Supervision either partially or simultaneously. The results of this research showed that partially, Competence and Motivation have no significant influence to the Quality of Financial Supervision at Dinas Pariwisata of North Sulawesi province, while partially in Independence variable, it has a significant influence to the Quality of Financial Supervision at Dinas Pariwisata of North Sulawesi Province. Simultaneously, Competence, Independence and Motivation are significantly influence the Quality of Financial Supervision at Dinas Pariwisata of North Sulawesi Province. Keywords: financial supervision quality, competence, independence, motivation

Resonant tunneling and the multichannel Kondo problem: the quantum Brownian motion description

We study mesoscopic resonant tunneling as well as multichannel Kondo problems by mapping them to a first-quantized quantum mechanical model of a particle moving in a multi-dimensional periodic potential with Ohmic dissipation. From a renormalization group analysis, we obtain phase diagrams of the quantum Brownian motion model with various lattice symmetries. For a symmorphic lattice, there are two phases at T=0: a localized phase in which the particle is trapped in a potential minimum, and a free phase in which the particle is unaffected by the periodic potential. For a non-symmorphic lattice, however, there may be an additional intermediate phase in which the particle is neither localized nor completely free. The fixed point governing the intermediate phase is shown to be identical to the well-known multichannel Kondo fixed point in the Toulouse limit as well as the resonance fixed point of a quantum dot model and a double-barrier Luttinger liquid model. The mapping allows us to compute the fixed-poing mobility $\mu^*$ of the quantum Brownian motion model exactly, using known conformal-field-theory results of the Kondo problem. From the mobility, we find that the peak value of the conductance resonance of a spin-1/2 quantum dot problem is given by $e^2/2h$. The scaling form of the resonance line shape is predicted

Crossover and self-averaging in the two-dimensional site-diluted Ising model

Using the newly proposed probability-changing cluster (PCC) Monte Carlo algorithm, we simulate the two-dimensional (2D) site-diluted Ising model. Since we can tune the critical point of each random sample automatically with the PCC algorithm, we succeed in studying the sample-dependent $T_c(L)$ and the sample average of physical quantities at each $T_c(L)$ systematically. Using the finite-size scaling (FSS) analysis for $T_c(L)$, we discuss the importance of corrections to FSS both in the strong-dilution and weak-dilution regions. The critical phenomena of the 2D site-diluted Ising model are shown to be controlled by the pure fixed point. The crossover from the percolation fixed point to the pure Ising fixed point with the system size is explicitly demonstrated by the study of the Binder parameter. We also study the distribution of critical temperature $T_c(L)$. Its variance shows the power-law $L$ dependence, $L^{-n}$, and the estimate of the exponent $n$ is consistent with the prediction of Aharony and Harris [Phys. Rev. Lett. {\bf 77}, 3700 (1996)]. Calculating the relative variance of critical magnetization at the sample-dependent $T_c(L)$, we show that the 2D site-diluted Ising model exhibits weak self-averaging.Comment: 6 pages including 6 eps figures, RevTeX, to appear in Phys. Rev.

Conformal Field Theory and Hyperbolic Geometry

We examine the correspondence between the conformal field theory of boundary operators and two-dimensional hyperbolic geometry. By consideration of domain boundaries in two-dimensional critical systems, and the invariance of the hyperbolic length, we motivate a reformulation of the basic equation of conformal covariance. The scale factors gain a new, physical interpretation. We exhibit a fully factored form for the three-point function. A doubly-infinite discrete series of central charges with limit c=-2 is discovered. A correspondence between the anomalous dimension and the angle of certain hyperbolic figures emerges. Note: email after 12/19: [email protected]: 7 pages (PlainTeX

Entangling quantum measurement and its properties

We study the mathematical structure of superoperators describing quantum measurements, including the \emph{entangling measurement}--the generalization of the standard quantum measurement that results in entanglement between the measurable system and apparatus. It is shown that the coherent information can be effectively used for the analysis of such entangling measurements whose possible applications are discussed as well.Comment: 8 pages, 1 figure; accepted for publication in Phys. Rev.

Disordered Dirac Fermions: Multifractality Termination and Logarithmic Conformal Field Theories

We reexamine in detail the problem of fermions interacting with a non-Abelian random vector potential. Without resorting to the replica or supersymmetry approaches, we show that in the limit of infinite disorder strength the theory possesses an exact solution which takes the form of a logarithmic conformal field theory. We show that the proper treatment of the locality conditions in the SU(2) theory leads to the termination of the multifractal spectrum, or in other words to the termination of the infinite hierarchies of negative-dimensional operators that were thought to occur. Based on arguments of logarithmic degeneracies, we conjecture that such a termination mechanism should be present for general SU(N). Moreover, our results lead to the conclusion that the previous replica solution of this problem yields incorrect results.Comment: Revised version, to appear in Nucl. Phys.

Tunneling times with covariant measurements

We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never in favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define ``the same incoming state'' and ''the same detector'' when comparing the settings with and without tunnel potential. The arrival time measurements are expressed in the time-covariant approach, but we also allow the detection to be a localization measurement at a later time.Comment: 12 pages, 2 figure

Schwinger-Keldysh Approach to Disordered and Interacting Electron Systems: Derivation of Finkelstein's Renormalization Group Equations

We develop a dynamical approach based on the Schwinger-Keldysh formalism to derive a field-theoretic description of disordered and interacting electron systems. We calculate within this formalism the perturbative RG equations for interacting electrons expanded around a diffusive Fermi liquid fixed point, as obtained originally by Finkelstein using replicas. The major simplifying feature of this approach, as compared to Finkelstein's is that instead of $N \to 0$ replicas, we only need to consider N=2 species. We compare the dynamical Schwinger-Keldysh approach and the replica methods, and we present a simple and pedagogical RG procedure to obtain Finkelstein's RG equations.Comment: 22 pages, 14 figure

Extended multiplet structure in Logarithmic Conformal Field Theories

We use the process of quantum hamiltonian reduction of SU(2)_k, at rational level k, to study explicitly the correlators of the h_{1,s} fields in the c_{p,q} models. We find from direct calculation of the correlators that we have the possibility of extra, chiral and non-chiral, multiplet structure in the h_{1,s} operators beyond the `minimal' sector. At the level of the vacuum null vector h_{1,2p-1}=(p-1)(q-1) we find that there can be two extra non-chiral fermionic fields. The extra indicial structure present here permeates throughout the entire theory. In particular we find we have a chiral triplet of fields at h_{1,4p-1}=(2p-1)(2q-1). We conjecture that this triplet algebra may produce a rational extended c_{p,q} model. We also find a doublet of fields at h_{1,3p-1}=(\f{3p}{2}-1)(\f{3q}{2}-1). These are chiral fermionic operators if p and q are not both odd and otherwise parafermionic.Comment: 24 pages LATEX. Minor corrections and extra reference