arXiv subjects

R. Jafari

Publications and source records attributed to R. Jafari.

57 records · Page 4Linked to original sources

arXiv2007

Renormalization of concurrence: the application of quantum renormalization group to the quantum information systems

We have combined the idea of renormalization group and quantum information theory. We have shown how the entanglement or concurrence evolve as the size of the system being large, i.e. the finite size scaling is obtained. Moreover, It introduces how the renormalization group approach can be implemented to obtain the quantum information properties of a many body system. We have obtained the concurrence as a measure of entanglement, its derivatives and their scaling behavior versus the size of system for the one dimensional Ising model in transverse field. We have found that the derivative of concurrence between two blocks each containing half of the system size diverges at the critical point with the exponent which is directly associated with the divergence of the correlation length.

quant-ph↗

arXiv2007

Phase Diagram of the One Dimensional $S=1/2$ $XXZ$ model with Ferromagnetic nearest-neighbor and Antiferromagnetic next-nearest neighbor interactions

We have studied the phase diagram of the one dimensional $S=1/2$ $XXZ$ model with ferromagnetic nearest-neighbor and antiferromagnetic next-nearest neighbor interactions. We have applied the quantum renormalization group (QRG) approach to get the stable fixed points and the running of coupling constants. The second order QRG has been implemented to get the self similar Hamiltonian. This model shows a rich phase diagram which consists of different phases which possess the quantum spin-fluid and dimer phases in addition to the classical Néel and ferromagnetic ones. The border between different phases has been shown as a projection onto two different planes in the phase space.

cond-mat.str-el↗

arXiv2005

Second order quantum renormalisation group of XXZ chain with next nearest neighbour interactions

We have extended the application of quantum renormalisation group (QRG) to the anisotropic Heisenberg model with next-nearest neighbour (n-n-n) interaction. The second order correction has to be taken into account to get a self similar renormalized Hamiltonian in the presence of n-n-n-interaction. We have obtained the phase diagram of this model which consists of three different phases, i.e, spin-fluid, dimerised and Ne'el types which merge at the tri-critical point. The anisotropy of the n-n-n-term changes the phase diagram significantly. It has a dominant role in the Ne'el-dimer phase boundary. The staggered magnetisation as an order parameter defines the border between fluid-Ne'el and Ne'el-dimer phases. The improvement of the second order RG corrections on the ground state energy of the Heisenberg model is presented. Moreover, the application of second order QRG on the spin lattice model has been discussed generally. Our scheme shows that higher order corrections lead to an effective Hamiltonian with infinite range of interactions.

cond-mat.stat-mech↗