1,721,050 research outputs found
Universal corrections to scaling for block entanglement in spin-1/2 XX chains
No full textWe consider the Rényi entropies Sn(ℓ) in the one-dimensional spin- 1/2 Heisenberg XX chain in a magnetic field. The case n = 1 corresponds to the von Neumann 'entanglement' entropy. Using a combination of methods based on the generalized Fisher-Hartwig conjecture and a recurrence relation connected to the Painlevé VI differential equation we obtain the asymptotic behaviour, accurate to order O(ℓ-3), of the Rényi entropies Sn(ℓ) for large block lengths ℓ. For n = 1, 2, 3, 10 this constitutes the 3, 6, 10, 48 leading terms respectively. The o(1) contributions are found to exhibit a rich structure of oscillatory behaviour, which we analyse in some detail both for finite n and in the limit n → ∞. © 2010 IOP Publishing Ltd and SISSA
Quantum Quench in the Transverse Field Ising Chain II: Stationary State Properties
No full textWe consider the stationary state properties of the reduced density matrix as well as spin-spin correlation functions after a sudden quantum quench of the magnetic field in the transverse field Ising chain. We demonstrate that stationary state properties are described by a generalized Gibbs ensemble. We discuss the approach to the stationary state at late times
Quantum Quench in the Transverse Field Ising chain I: Time evolution of order parameter correlators
No full textWe consider the time evolution of order parameter correlation functions after a sudden quantum quench of the magnetic field in the transverse field Ising chain. Using two novel methods based on determinants and form factor sums respectively, we derive analytic expressions for the asymptotic behaviour of one and two point correlators. We discuss quenches within the ordered and disordered phases as well as quenches between the phases and to the quantum critical point. We give detailed account of both methods
Quantum quench in the transverse-field Ising chain.
No full textWe consider the time evolution of observables in the transverse-field Ising chain after a sudden quench of the magnetic field. We provide exact analytical results for the asymptotic time and distance dependence of one- and two-point correlation functions of the order parameter. We employ two complementary approaches based on asymptotic evaluations of determinants and form-factor sums. We prove that the stationary value of the two-point correlation function is not thermal, but can be described by a generalized Gibbs ensemble (GGE). The approach to the stationary state can also be understood in terms of a GGE. We present a conjecture on how these results generalize to particular quenches in other integrable models
Quantum criticalities in a two-leg antiferromagnetic S=1/2 ladder induced by a staggered magnetic field
No full textWe study a two-leg antiferromagnetic spin-1/2 ladder in the presence of a staggered magnetic field. We consider two parameter regimes: strong (weak) coupling along the legs and weak (strong) coupling along the rungs. In both cases, the staggered field drives the Haldane spin-liquid phase of the ladder towards a Gaussian quantum criticality. In a generalized spin ladder with a non-Haldane, spontaneously dimerized phase, the staggered magnetic field induces an Ising quantum critical regime. In the vicinity of the critical lines, we derive low-energy effective field theories and use these descriptions to determine the dynamical response functions, the staggered spin susceptibility, and the string order parameter
The supersymmetric t-J model with a boundary
No full textAn open supersymmetric t-J chain with boundary fields is studied by means of the Bethe ansatz. Ground state properties for the case of an almost half-filled band and a bulk magnetic field are determined. Boundary susceptibilities are calculated as functions of the boundary fields. The effects of the boundary on excitations are investigated by constructing the exact boundary S-matrix. From the analytic structure of the boundary S-matrices one deduces that holons can form boundary bound states for sufficiently strong boundary fields
Threshold singularities in the one-dimensional Hubbard model
No full textWe consider excitations with the quantum numbers of a hole in the one-dimensional Hubbard model below half-filling. We calculate the finite-size corrections to the energy. The results are then used to determine threshold singularities in the single-particle Green's function for commensurate fillings. We present the analogous results for the Yang-Gaudin model (electron gas with δ -function interactions). © 2010 The American Physical Society
Three-particle scattering continuum in quasi-one-dimensional integer-spin Heisenberg magnets
No full textWe analyze the three-particle scattering continuum in quasi-one-dimensional integer spin Heisenberg antiferromagnets within a low-energy effective field theory framework. We exactly determine the zero-temperature dynamical structure factor in the O(3) nonlinear σ model and in Tsvelik's Majorana fermion theory. We study the effects of interchain coupling in a random phase approximation. We discuss the application of our results to recent neutron-scattering experiments on the spin-1 Haldane-gap material CsNiCl3. ©2000 The American Physical Society
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