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Transverse Field (transverse + field)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Entanglement and symmetry effects in the transition to the Schrödinger cat regime

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 11-12 2009
F. de Pasquale
Abstract We study two-spin entanglement and order parameter fluctuations as a function of the system size in the XY model in a transverse field and in the isotropic XXX model. Both models are characterized by the occurrence of ground state degeneracy also when systems of finite size are considered. This is always true for the XXX model, but only at the factorizing field for the XY model. We study the size dependence of symmetric states, which, in the presence of degeneracy, can be expanded as a linear combination of broken symmetry states. We show that, while the XY model looses its quantum superposition content exponentially with the size N, a decrease of the order of 1 / N is observed when the XXX model is considered. The emergence of two qualitatively different regimes is directly related to the difference in the symmetry of the models. [source]

VSOP polarization observations of the BL Lacertae object OJ 287

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001
D. C. Gabuzda
VLBI total intensity and linear polarization images of the BL Lacertae object OJ 287 have been obtained at using a global ground array and the HALCA orbiting antenna, and at two weeks earlier using the VLBA. In the ground-based 6-cm images, the source is dominated by a core,jet double structure the components of which are essentially unresolved. The baselines to the orbiting antenna resolve both of these compact components. In the VSOP images, the ground-based ,core' breaks up into several distinct components, demonstrating that this region is dominated by the contribution of bright, optically thin knots of jet emission. A very similar structure is observed in the 1.3-cm image. The magnetic field in the core is transverse, becomes longitudinal in the inner jet, then makes a sharp transition to a region of transverse field further from the core. This suggests that the field in the outer jet has become highly ordered in the transverse direction owing to the action of a shock; the physical nature of the extended region of longitudinal field closer to the core is not clear. The availability of nearly simultaneous observations with comparable resolution at widely spaced frequencies enabled detection of a ,90° rotation in polarization position angle for the core, owing to the transition from the optically thick (6 cm) to the optically thin (1.3 cm) regime. [source]

Short-range ±J interaction Ising spin glass in a transverse field on a Bethe lattice: a quantum-spherical approach

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2006
T. K. Kope
Abstract We consider the short-range interaction disordered quantum Ising model with symmetric binary ±J bond distribution on the Bethe lattice (with coordination number z). The system exhibits quantum phase transition separating the spin glass and disordered phases where the quantum effect are regulated by a param- eter , describing the transverse field. By introducing a mapping of the quantum Hamiltonian of the model onto a soft-spin action we consider it truncated version in a form of the solvable quantized spherical model. Quantum dynamics is examined via various correlation functions on the infinite tree which are evaluated in a closed form. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Tricritical behavior of Ising metamagnet in both external longitudinal and transverse fields

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2007
Jing Liu
Abstract A two-sublattice Ising metamagnet in both external longitudinal and transverse fields is studied within the mean-field approach based on Bogoliubov's inequality for the Gibbs free energy. The phase diagrams in the longitudinal field-temperature plane and in the transverse field-temperature plane are determined, respectively. The results show that the tricritical points can occur in a certain region of the external longitudinal and transverse fields, the temperature of the tricritical point monotonically increases with decreasing the transverse magnetic field , and increasing the longitudinal magnetic field h. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]