: It is shown that, with an appropriate scaling, the energy of lowlying excitations of the (1; 1; : : : ; 1) interface in the d-dimensional quantum Heisenberg model are given by the spectrum of the d \Gamma 1-dimensional Laplacian on an suitable domain. Keywords: Anisotropic Heisenberg ferromagnet

We propose uncertainty relations for the different coordinates of spacetime events, motivated by Heisenberg’s principle and by Einstein’s theory of classical gravity. A model of Quantum Spacetime is then discussed where the commutation relations exactly implement our uncertainty relations. We

d-dimensional quasiperi-odic tilings are constructed from the product of d such chains, which yields either the square/cubic Fibonacci tiling or the labyrinth tiling. We study the scaling be-havior of the mean square displacement and the return probability of wave packets with respect to time. We

The model which generalizes Ponzano and Regge 3D and Carfora-Martellini-Marzuoli 4D euclidean quantum gravity is considered. The euclidean Einstein-Regge action for a D-simplex is given in the semiclassical limit by a gaussian integral of a suitable 3nj-symbol. 1 On leave from Department of Physics

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We study the entanglement in the quantum Heisenberg XY model in which the so-called W entangled states can be generated for 3 or 4 qubits. By the concept of concurrence, we study the entanglement in the time evolution of the XY model. We investigate the thermal entanglement in the two

We derive the loop equations for the d-dimensional n-Hermitian matrix model. These are a consequence of the Schwinger-Dyson equations of the model. Moreover we show that in leading order of large N the loop equations form a closed set. In particular we derive the loop equations for the n = 2 k

interacting spins are located on a two-dimensional square lattice. Although simple to formulate, the Heisenberg model is not exactly solvable in dimensions greater than one, and approximations or numerical calculations are needed to compare the predictions of the Heisenberg model to experiments. For the 2D

for this complex quantum-impurity problem. 1 The field of low-dimensional quantum magnetism has been of enormous interest to the condensed-matter physics community ever since the discovery that La2CuO4, the parent compound of the original high-temperature superconductor (La,Ba)2CuO4, is a model two-dimensional (2D

The Holstein-Primakoff (HP) bosonic representation of the QFHM. 2 The regime with spin S → ∞ and β = O(S−1) [CS1]: Main result [CG]: Free Energy (FE) asymptotics as S →∞. Sketch of the proof: upper and lower bounds. 3 The regime with spin S = 12 and β → ∞ [CS2,T]: Main result [CGS]: sharp upper bound to the FE as β →∞.