A Hybrid Quantum Encoding Algorithm of Vector Quantization for Image Compression

Many classical encoding algorithms of Vector Quantization (VQ) of image compression that can obtain global optimal solution have computational complexity O(N). A pure quantum VQ encoding algorithm with probability of success near 100% has been proposed, that performs operations 45sqrt(N) times approximately. In this paper, a hybrid quantum VQ encoding algorithm between classical method and quantum algorithm is presented. The number of its operations is less than sqrt(N) for most images, and it is more efficient than the pure quantum algorithm. Key Words: Vector Quantization, Grover's Algorithm, Image Compression, Quantum AlgorithmComment: Modify on June 21. 10pages, 3 figure

Normal families and fixed points of iterates

Let F be a family of holomorphic functions and let K be a constant less than 4. Suppose that for all f in F the second iterate of f does not have fixed points for which the modulus of the multiplier is greater than K. We show that then F is normal. This is deduced from a result about the multipliers of iterated polynomials.Comment: 5 page

On the kinks and dynamical phase transitions of alpha-helix protein chains

Heuristic insights into a physical picture of Davydov's solitonic model of the one-dimensional protein chain are presented supporting the idea of a non-equilibrium competition between the Davydov phase and a complementary, dynamical- `ferroelectric' phase along the chainComment: small latex file with possible glue problems, just go on !, no figures, small corrections with respect to the published text, follow-up work to cond-mat/9304034 [PRE 47 (June 1993) R3818

Analytic Lifshitz black holes in higher dimensions

We generalize the four-dimensional R^2-corrected z=3/2 Lifshitz black hole to a two-parameter family of black hole solutions for any dynamical exponent z and for any dimension D. For a particular relation between the parameters, we find the first example of an extremal Lifshitz black hole. An asymptotically Lifshitz black hole with a logarithmic decay is also exhibited for a specific critical exponent depending on the dimension. We extend this analysis to the more general quadratic curvature corrections for which we present three new families of higher-dimensional D>=5 analytic Lifshitz black holes for generic z. One of these higher-dimensional families contains as critical limits the z=3 three-dimensional Lifshitz black hole and a new z=6 four-dimensional black hole. The variety of analytic solutions presented here encourages to explore these gravity models within the context of non-relativistic holographic correspondence.Comment: 14 page

Ferromagnetism in the Infinite-U Hubbard Model

We have studied the stability of the ferromagnetic state in the infinite-U Hubbard model on a square lattice by approximate diagonalization of finite lattices using the density matrix renormalization group technique. By studying lattices with up to 5X20 sites, we have found the ferromagnetic state to be stable below the hole density of 22 percent. Beyond 22 percent of hole doping, the total spin of the ground state decreased gradually to zero with increasing hole density.Comment: 13 pages, RevteX 3.0, seven figures appended in uuencoded form, correcting problems with uuencoded figure

Solution of two channel spin-flavor Kondo model

We investigate a model where an impurity couples to both the spin and the flavor currents of the two channel conduction electrons. This model can be used as a prototype model of a magnetic impurity tunneling between two sites in a metal and of some heavy fermion systems where the ground state of the impurity has a fourfold degeneracy. The system is shown to flow to a doubly degenerate non fermi-liquid(NFL) fixed point; the thermodynamic quantities show NFL behaviors, but the transport quantities show fermi liquid (FL) behaviors . A spin-flavor coupling double tensor term is shown to drive the system to one of the two singlet FL fixed points. The relation with SU(4) Coqblin-Schrieffer model is studied. The implications on the possible experiments are given.Comment: 11 pages, REVTEX, no figures. To appear in Phys. Rev. B (Rapid Comm.) July 1, 199

Thermodynamics of Dyonic Lifshitz Black Holes

Black holes with asymptotic anisotropic scaling are conjectured to be gravity duals of condensed matter system close to quantum critical points with non-trivial dynamical exponent z at finite temperature. A holographic renormalization procedure is presented that allows thermodynamic potentials to be defined for objects with both electric and magnetic charge in such a way that standard thermodynamic relations hold. Black holes in asymptotic Lifshitz spacetimes can exhibit paramagnetic behavior at low temperature limit for certain values of the critical exponent z, whereas the behavior of AdS black holes is always diamagnetic.Comment: 26 pages, 4 figure

Black holes and black branes in Lifshitz spacetimes

We construct analytic solutions describing black holes and black branes in asymptotically Lifshitz spacetimes with arbitrary dynamical exponent z and for arbitrary number of dimensions. The model considered consists of Einstein gravity with negative cosmological constant, a scalar, and N U(1) gauge fields with dilatonic-like couplings. We study the phase diagrams and thermodynamic instabilities of the solution, and find qualitative differences between the cases with 12.Comment: 27 pages, 10 figures; v2 references added, minor comments adde

Simple description of the anisotropic two-channel Kondo problem

We adapt strong-coupling methods first used in the one-channel Kondo model to develop a simple description of the spin-$1\over 2$ two-channel Kondo model with channel anisotropy. Our method exploits spin-charge decoupling to develop a compactified Hamiltonian that describes the spin excitations. The structure of the fixed-point Hamiltonian and quasiparticle impurity S-matrix are incompatible with a Fermi liquid description.Comment: 4 pages, latex (uses revtex and epsf macros) with 3 figures - all in a self unpacking uuencoded file. Revisions include changes to Fig. 1(a) and detailed discussion of the spin excitation

Study of the beam profile and position instability of a post-accelerated pseudospark-sourced electron beam

A pseudospark-sourced electron beam is a promising candidate for driving a THz millimeter wave radiation source. However, the physics governing the electron beam density profile and the beam center deviation from the axis of the structure, which may be caused by the randomness in the pseudospark discharge process, remains still unclear especially for the high energy component of the pseudospark-sourced electron beam which is usually non-mono-energetic. It is essential to study the electron beam density profile and the beam center position distribution for optimizing the pseudospark discharge configuration. In this paper, images of some single-shot electron beam pulses have been captured using a 50 μm thickness stopping copper foil and a phosphor screen coated with P47 scintillator to study the electron beam density profile and the beam center position distribution of the high energy component of the electron beam. The experiments have been carried out on two pseudospark discharge configurations with two different size hollow cathode cavities. The influence of the cathode aperture of each configuration has also been studied according to the beam images. Experimental results show that the beam profile of the high energy component has a Lorentzian distribution and is much smaller than the axial aperture size with the beam centers dispersing within a certain range around the axis of the discharge structure. The pseudospark-sourced electron beam with the larger hollow cathode cavity shows smaller full width at half maximum (FWHM) radius and a more concentrated beam center distribution