25 research outputs found
Arnold Tongues and Feigenbaum Exponents of the Rational Mapping for Q-state Potts Model on Recursive Lattice: Q<2
We considered Q-state Potts model on Bethe lattice in presence of external
magnetic field for Q<2 by means of recursion relation technique. This allows to
study the phase transition mechanism in terms of the obtained one dimensional
rational mapping. The convergence of Feigenabaum and
exponents for the aforementioned mapping is investigated for the period
doubling and three cyclic window. We regarded the Lyapunov exponent as an order
parameter for the characterization of the model and discussed its dependence on
temperature and magnetic field. Arnold tongues analogs with winding numbers
w=1/2, w=2/4 and w=1/3 (in the three cyclic window) are constructed for Q<2.
The critical temperatures of the model are discussed and their dependence on Q
is investigated. We also proposed an approximate method for constructing Arnold
tongues via Feigenbaum exponent.Comment: 15 pages, 12 figure
Magnetic Properties and Thermal Entanglement on a Triangulated Kagome Lattice
The magnetic and entanglement thermal (equilibrium) properties in spin-1/2
Ising-Heisenberg model on a triangulated Kagome lattice are analyzed by means
of variational mean-field like treatment based on Gibbs-Bogoliubov inequality.
Because of the separable character of Ising-type exchange interactions between
the Heisenberg trimers the calculation of quantum entanglement in a
self-consistent field can be performed for each of the trimers individually.
The concurrence in terms of three qubit isotropic Heisenberg model in effective
Ising field is non-zero even in the absence of a magnetic field. The magnetic
and entanglement properties exhibit common (plateau and peak) features
observable via (antferromagnetic) coupling constant and external magnetic
field. The critical temperature for the phase transition and threshold
temperature for concurrence coincide in the case of antiferromagnetic coupling
between qubits. The existence of entangled and disentangled phases in saturated
and frustrated phases is established.Comment: 21 pages, 13 figure
Thermal Entanglement of a Spin-1/2 Ising-Heisenberg Model on a Symmetrical Diamond Chain
The entanglement quantum properties of a spin-1/2 Ising-Heisenberg model on a
symmetrical diamond chain were analyzed. Due to the separable nature of the
Ising-type exchange interactions between neighboring Heisenberg dimers,
calculation of the entanglement can be performed exactly for each individual
dimer. Pairwise thermal entanglement was studied in terms of the isotropic
Ising-Heisenberg model, and analytical expressions for the concurrence (as a
measure of bipartite entanglement) were obtained. The effects of external
magnetic field and next-nearest neighbor interaction between nodal
Ising sites were considered. The ground-state structure and entanglement
properties of the system were studied in a wide range of the coupling constant
values. Various regimes with different values of the ground-state entanglement
were revealed, depending on the relation between competing interaction
strengths. Finally, some novel effects, such as the two-peak behavior of
concurrence versus temperature and coexistence of phases with different values
of magnetic entanglement were observed
Pairwise thermal entanglement in Ising-XYZ diamond chain structure in an external magnetic field
Quantum entanglement is one of the most fascinating types of correlation that
can be shared only among quantum systems. The Heisenberg chain is one of the
simplest quantum chains which exhibits a reach entanglement feature, due to the
Heisenberg interaction is quantum coupling in the spin system. The two
particles were coupled trough XYZ coupling or simply called as two-qubit XYZ
spin, which are the responsible for the emergence of thermal entanglement.
These two-qubit operators are bonded to two nodal Ising spins, and this process
is repeated infinitely resulting in a diamond chain structure. We will discuss
two-qubit thermal entanglement effect on Ising-XYZ diamond chain structure. The
concurrence could be obtained straightforwardly in terms of two-qubit density
operator elements, using this result, we study the thermal entanglement, as
well as the threshold temperature where entangled state vanishes. The present
model displays a quite unusual concurrence behavior, such as, the boundary of
two entangled regions becomes a disentangled region, this is intrinsically
related to the XY-anisotropy in the Heisenberg coupling. Despite a similar
property had been found for only two-qubit, here we show in the case of a
diamond chain structure, which reasonably represents real materials.Comment: 6 pages, 7 figure
Azimuthal Dependence of the Heavy Quark Initiated Contributions to DIS
We analyze the azimuthal dependence of the heavy-quark-initiated
contributions to the lepton-nucleon deep inelastic scattering (DIS). First we
derive the relations between the parton level semi-inclusive structure
functions and the helicity cross sections in the case of
arbitrary values of the heavy quark mass. Then the azimuth-dependent lepton-quark DIS is calculated in the helicity basis. Finally,
we investigate numerically the properties of the and
distributions caused by the photon-quark scattering (QS) contribution. It turns
out that, contrary to the basic photon-gluon fusion (GF) component, the QS
mechanism is practically -independent. This fact implies that
measurements of the azimuthal distributions in charm leptoproduction could
directly probe the charm density in the proton.Comment: 11 pages, 4 figures, revtex4, published versio
Phase transitions and entanglement properties in spin-1 Heisenberg clusters with single-ion anisotropy
The incipient quantum phase transitions of relevance to nonzero fluctuations
and entanglement in Heisenberg clusters are studied in this paper by exploiting
negativity as a measure in bipartite and frustrated spin-1 anisotropic
Heisenberg clusters with bilinear-biquadratic exchange, single-ion anisotropy
and magnetic field. Using the exact diagonalization technique, it is shown that
quantum critical points signaled by qualitative changes in behavior of
magnetization and particle number are ultimately related to microscopic
entanglement and collective excitations. The plateaus and peaks in spin and
particle susceptibilities define the conditions for a high/low-density quantum
entanglement and various ordered phases with different spin (particle)
concentrations
Deformation of orthosymplectic Lie superalgebra osp(1|2)
Triangular deformation of the orthosymplectic Lie superalgebra osp(1|4) is
defined by chains of twists. Corresponding classical r-matrix is obtained by a
contraction procedure from the trigonometric r-matrix. The carrier space of the
constant r-matrix is the Borel subalgebra.Comment: LaTeX, 8 page
Magnetic and quantum entanglement properties of the distorted diamond chain model for azurite
We present the results of magnetic properties and entanglement of the
distorted diamond chain model for azurite using pure quantum exchange
interactions. The magnetic properties and concurrence as a measure of pairwise
thermal entanglement have been studied by means of variational mean-field like
treatment based on Gibbs-Bogoliubov inequality. Such a system can be considered
as an approximation of the natural material azurite, Cu3(CO3)2(OH)2. For values
of exchange parameters, which are taken from experimental results, we study the
thermodynamic properties, such as azurite specific heat and magnetic
susceptibility. We also have studied the thermal entanglement properties and
magnetization plateau of the distorted diamond chain model for azurite