55 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
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
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
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
The study of the biological activities of Ziziphora clinopodioides
The aim of the current study was to determine the chemical constituents of essential oil and to study the antibacterial and antioxidant activities of essential oil and the extracts obtained from the raw material of Ziziphora wild growing in the floras of Armenia and Artsakh cultivated in the hydroponic conditions. The essential oils were obtained by the method of hydro-distillation. The determination of the essential oil constituents were performed by the GC-MS method. Agar disk diffusion method was used to study the antimicrobial activity of essential oils. The antioxidant activity determination was carried out DPPH test by the spectrophotometric method, at the same time IC50 was determined. The highest values of the essential oils yield (1.25 ± 0.01%) and IC50 13.83±0.218(x10-5)g/l) were received for the plant cultivated in hydroponic conditions. For the first time in the above studied samples, by the method of GC-MS more than 70 components were revealed. The results of the study showed that essential oils of Ziziphora exhibit antimicrobial activity and the extracts revealed relatively expressed antioxidant activity. The study results show the future prospects of the use of Ziziphora not only as the source of flavonoids and essential oils, but also antimicrobial and antioxidant agents
Thermal Entanglement and Critical Behavior of Magnetic Properties on a Triangulated Kagomé Lattice
The equilibrium magnetic and entanglement properties in a spin-1/2 Ising-Heisenberg model on a triangulated Kagomé lattice are analyzed by means of the effective field for the Gibbs-Bogoliubov inequality. The calculation is reduced to decoupled individual (clusters) trimers due to the separable character of the Ising-type exchange interactions between the Heisenberg trimers. The concurrence in terms of the three qubit isotropic Heisenberg model in the effective Ising field in the absence of a magnetic field is non-zero. The magnetic and entanglement properties exhibit common (plateau, peak) features driven by a magnetic field and (antiferromagnetic) exchange interaction. The (quantum) entangled and non-entangled phases can be exploited as a useful tool for signalling the quantum phase transitions and crossovers at finite temperatures. The critical temperature of order-disorder coincides with the threshold temperature of thermal entanglement
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