19,651 research outputs found

    Supersymmetric Reciprocal Transformation and Its Applications

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    The supersymmetric analog of the reciprocal transformation is introduced. This is used to establish a transformation between one of the supersymmetric Harry Dym equations and the supersymmetric modified Korteweg-de Vries equation. The reciprocal transformation, as a B\"{a}cklund-type transformation between these two equations, is adopted to construct a recursion operator of the supersymmetric Harry Dym equation. By proper factorization of the recursion operator, a bi-Hamiltonian structure is found for the supersymmetric Harry Dym equation. Furthermore, a supersymmetric Kawamoto equation is proposed and is associated to the supersymmetric Sawada-Kotera equation. The recursion operator and odd bi-Hamiltonian structure of the supersymmetric Kawamoto equation are also constructed.Comment: 31 pages, expande

    Two-qubit Quantum Logic Gate in Molecular Magnets

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    We proposed a scheme to realize a controlled-NOT quantum logic gate in a dimer of exchange coupled single-molecule magnets, [Mn4]2[\textrm{Mn}_4]_2. We chosen the ground state and the three low-lying excited states of a dimer in a finite longitudinal magnetic field as the quantum computing bases and introduced a pulsed transverse magnetic field with a special frequency. The pulsed transverse magnetic field induces the transitions between the quantum computing bases so as to realize a controlled-NOT quantum logic gate. The transition rates between the quantum computing bases and between the quantum computing bases and other excited states are evaluated and analyzed.Comment: 7 pages, 2 figure

    Charge-stripe order in the electronic ferroelectric LuFe2O4

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    The structural features of the charge ordering states in LuFe2O4 are characterized by in-situ cooling TEM observations from 300K down to 20K. Two distinctive structural modulations, a major q1= (1/3, 1/3, 2) and a weak q2=q1/10 + (0, 0, 3/2), have been well determined at the temperature of 20K. Systematic analysis demonstrates that the charges at low temperatures are well crystallized in a charge stripe phase, in which the charge density wave behaviors in a non-sinusoidal fashion resulting in elemental electric dipoles for ferroelectricity. It is also noted that the charge ordering and ferroelectric domains often change markedly with lowering temperatures and yields a rich variety of structural phenomena.Comment: 15 pages, 4 figure

    Non-additivity of decoherence rates in superconducting qubits

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    We show that the relaxation and decoherence rates 1/T_1 and 1/T_2 of a qubit coupled to several noise sources are in general not additive, i.e., that the total rates are not the sums of the rates due to each individual noise source. To demonstrate this, we calculate the relaxation and pure dephasing rates 1/T_1 and 1/T_\phi of a superconducting (SC) flux qubit in the Born-Markov approximation in the presence of several circuit impedances Z_i using network graph theory and determine their deviation from additivity (the mixing term). We find that there is no mixing term in 1/T_\phi and that the mixing terms in 1/T_1 and 1/T_2 can be positive or negative, leading to reduced or enhanced relaxation and decoherence times T_1 and T_2. The mixing term due to the circuit inductance L at the qubit transition frequency \omega_{01} is generally of second order in \omega_{01}L/Z_i, but of third order if all impedances Z_i are pure resistances. We calculate T_{1,2} for an example of a SC flux qubit coupled to two impedances.Comment: 5 pages, 2 figure

    Quantum Phase Diffusion in a Small Underdamped Josephson Junction

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    Quantum phase diffusion in a small underdamped Nb/AlOx_x/Nb junction (∼\sim 0.4 μ\mum2^2) is demonstrated in a wide temperature range of 25-140 mK where macroscopic quantum tunneling (MQT) is the dominant escape mechanism. We propose a two-step transition model to describe the switching process in which the escape rate out of the potential well and the transition rate from phase diffusion to the running state are considered. The transition rate extracted from the experimental switching current distribution follows the predicted Arrhenius law in the thermal regime but is greatly enhanced when MQT becomes dominant.Comment: 4 pages, 4 figures, 1 tabl

    Interaction of Individual Skyrmions in Nanostructured Cubic Chiral Magnet

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    We report the direct evidence of field-dependent character of the interaction between individual magnetic skyrmions as well as between skyrmions and edges in B20-type FeGe nanostripes observed by means of high resolution Lorentz transmission electron microscopy. It is shown that above certain critical values of external magnetic field the character of such long-range skyrmion interactions change from attraction to repulsion. Experimentally measured equilibrium inter-skyrmion and skrymion-edge distances as function of applied magnetic field shows quantitative agreement with the results of micromagnetic simulations. Important role of demagnetizing fields and internal symmetry of three-dimensional magnetic skyrmions are discussed in details.Comment: accepted in PR

    On the S-matrix renormalization in effective theories

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    This is the 5-th paper in the series devoted to explicit formulating of the rules needed to manage an effective field theory of strong interactions in S-matrix sector. We discuss the principles of constructing the meaningful perturbation series and formulate two basic ones: uniformity and summability. Relying on these principles one obtains the bootstrap conditions which restrict the allowed values of the physical (observable) parameters appearing in the extended perturbation scheme built for a given localizable effective theory. The renormalization prescriptions needed to fix the finite parts of counterterms in such a scheme can be divided into two subsets: minimal -- needed to fix the S-matrix, and non-minimal -- for eventual calculation of Green functions; in this paper we consider only the minimal one. In particular, it is shown that in theories with the amplitudes which asymptotic behavior is governed by known Regge intercepts, the system of independent renormalization conditions only contains those fixing the counterterm vertices with n≤3n \leq 3 lines, while other prescriptions are determined by self-consistency requirements. Moreover, the prescriptions for n≤3n \leq 3 cannot be taken arbitrary: an infinite number of bootstrap conditions should be respected. The concept of localizability, introduced and explained in this article, is closely connected with the notion of resonance in the framework of perturbative QFT. We discuss this point and, finally, compare the corner stones of our approach with the philosophy known as ``analytic S-matrix''.Comment: 28 pages, 10 Postscript figures, REVTeX4, submitted to Phys. Rev.

    Dynamic marketing capabilities, foreign ownership modes, sub-national locations and the performance of foreign affiliates in developing economies

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    Purpose – The purpose of this paper is to examine the role of dynamic marketing capabilities (DMC), foreign ownership modes and sub-national locations on the performance of foreign owned affiliates (FOAs) in developing economies. Design/methodology/approach – Based on a sample of 254 FOAs in Indian manufacturing sector (covering the period of 2000-2008 leading to 623 firm-year observations), the empirical paper adopts the panel data regression approach. Findings – The study confirms the significant importance of DMC to assist FOAs to gain better sales performance in an emerging market such as India. The findings indicate that Wholly Owned Foreign Affiliates (WOFAs) have better sales performance than International Joint Venture (IJV), and Majority-owned IJV (MAIJV) perform better than Minority-owned IJV (MIIJV) in the Indian manufacturing sector. The results confirm that effective deployment of DMC leads to better sales performance in WOFAs and to some extent in MAIJVs compared to MIIJVs. Perhaps the most interesting finding is that developing DMC in non-Metropolitan areas is associated with higher sales growth than in Metropolitan locations. Originality/value – The study contributes to the literature by examining the impact of DMC on performance of FOA by considering the organised manufacturing sector in a large and fast growing developing economy. In addition, the results for the moderating effects provide novel evidence of the conditions under which DMC of FOA interacts with different ownership modes and influence firm performance
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