Asim Kumar Ghosh — Page 2

arXiv2017

Thermally stable multipartite entanglements in the frustrated Heisenberg hexagon

Thermally stable quantum states with multipartite entanglements led by frustration are found in the antiferromagnetic spin-1/2 Heisenberg hexagon. The model has been solved exactly to obtain all analytic expressions of eigenvalues and eigenfunctions. Detection and characterizations for various types of entanglements have been carried out in terms of concurrence and entanglement witnesses based on several thermodynamic observables. Variations of entanglement properties with respect to temperature and frustration are discussed. Even though the frustration opposes the bipartite entanglement, it favors the multipartite entanglement. Entangled states exhibit robustness against the thermal effects in the presence of frustration and they are found to survive at any temperature.

quant-ph↗

arXiv2017

Multiple gaps in the tight-binding band of a pentagonal lattice

Multiple gaps in the tight-binding band of a pentagonal lattice are found. Unlike the Cairo pentagonal lattice this lattice is made of irregular pentagons with arms of different lengths. The tight-binding Hamiltonian is exactly solved to obtain analytic expressions of dispersion relations and eigenvectors. Four different band-gaps are identified along with two distinct indirect band-gaps at the Harrison point. Multiple band-gaps in this model may give rise to exotic electronic properties.

cond-mat.mes-hall↗