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Savanur K.,Raman Research Institute | Srikanth R.,Raman Research Institute | Srikanth R.,Poornaprajna Institute of Scientific Research
Scientometrics | Year: 2010

Collaborative coefficient (CC) is a measure of collaboration in research, that reflects both the mean number of authors per paper as well as the proportion of multi-authored papers. Although it lies between the values 0 and 1, and is 0 for a collection of purely single-authored papers, it is not 1 for the case where all papers are maximally authored, i. e., every publication in the collection has all authors in the collection as co-authors. We propose a simple modification of CC, which we call modified collaboration coefficient (or MCC, for short), which improves its performance in this respect. © 2009 Akadémiai Kiadó, Budapest, Hungary. Source


Sarkar S.,Poornaprajna Institute of Scientific Research
Physica B: Condensed Matter | Year: 2012

Atoms trapped in micro-cavities and interacting through the exchange of virtual photons can be modeled as an anisotropic Heisenberg spin-1/2 lattice. We do the quantum field theoretical study of such a system using the Abelian bosonization method followed by the renormalization group analysis. An infinite order BerezinskiiKosterlizThouless transition is replaced by second order XY transition even when an infinitesimal anisotropy in exchange coupling is introduced. We predict a quantum phase transition between the photonic Coulomb blocked induce Mott insulating and photonic superfluid phases due to detuning between the cavity and laser frequency. A large detuning favors the photonic superfluid phase. We also perform the analysis of Jaynes and Cumming Hamiltonian to support the results of quantum field theoretical study. © 2011 Elsevier B.V. All rights reserved. Source


Sarkar S.,Poornaprajna Institute of Scientific Research
Physica B: Condensed Matter | Year: 2015

Abstract We present the results of low lying collective mode of coupled optical cavity arrays. We derive the Dirac equation for this system and explain the existence of Majorana fermion mode in the system. We present quite a few analytical relations between the Rabi frequency oscillation and the atom-photon coupling strength to explain the different physical situation of our study and also the condition for massless collective mode in the system. We present several analytical relations between the Dirac spinor field, order and disorder operators for our systems. We also show that the Luttinger liquid physics is one of the intrinsic concepts in our system. © 2015 Published by Elsevier B.V. Source


Sarkar S.,Poornaprajna Institute of Scientific Research
Advances in Theoretical and Mathematical Physics | Year: 2014

We study the quantum phase transition of light of a system when atom trapped in microcavities and interacting through the exchange of virtual photons. We predict the quantum phase transition between the photonic Coulomb blocked induce insulating phase and anisotropic exchange induced photonic superfluid phase in the system due to the existence of two Rabi frequency oscillations. The renormalization group equation shows explicitly that for this system there is no self-duality. The system also shows two Berezinskii-Kosterlitz-Thouless (BKT) transitions for the different physical situation of the system. The presence of single Rabi frequency oscillation in the system leads to the BKT transition where system shows the quantum phase transition from photonic metallic state to the Coulomb blocked induced insulating phase. For the other BKT transition when the z-component of exchange interaction is absent, the system shows the transition from the photonic metallic state to the photonic superfluid phase. We also predict the commensurate to incommensurate transition under the laser field detuning. © 2014 International Press. Source


Sarkar S.,Poornaprajna Institute of Scientific Research
Physica B: Condensed Matter | Year: 2014

The atoms trapped in microcavities and interacting through the exchange of virtual photons can be modeled as an anisotropic Heisenberg spin-1/2 lattice. We study the dynamics of the geometric phase of this system under the linear quenching process of laser field detuning, which shows XX criticality of the geometric phase and also gives the result of quantum criticality for different quenching rates. © 2014 Published by Elsevier B.V. Source

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