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A. I. Nesterov

Publications and source records attributed to A. I. Nesterov.

6 recordsLinked to original sources
arXiv2020

Ultrafast dynamics of light-induced spin crossovers under high pressure

Within the multielectron model of magnetic insulator with spin crossover under high pressure we have studied the mean field phase diagrams in pressure temperature plane and dynamics of a sudden excited non equilibrium spin state. We obtain the different relaxation of the magnetization, high spin/low spin occupation numbers, and the metal oxygen bond length for different values of the external pressure. We found the long living oscillations of magnetization without pressure and at small external pressure. Close to crossover pressure the smooth relaxation is accompanied with a set of sharp strongly non linear oscillations of magnetization and HS/LS occupation numbers that are accompanied by the Franck Condon resonances.

cond-mat.str-el↗
arXiv2017

Production of Entanglement Entropy by Decoherence

We examine the dynamics of entanglement entropy of all parts in an open system consisting of a two-level dimer interacting with an environment of oscillators. The dimer-environment interaction is almost energy conserving. We find the precise link between decoherence and production of entanglement entropy. We show that not all environment oscillators carry significant entanglement entropy and we identify the oscillator frequency regions which contribute to the production of entanglement entropy. Our results hold for arbitrary strengths of the dimer-environment interaction, and they are mathematically rigorous.

quant-ph↗
arXiv2015

Dynamics of a Chlorophyll Dimer in Collective and Local Thermal Environments

We present a theoretical analysis of exciton transfer and decoherence effects in a photosynthetic dimer interacting with collective (correlated) and local (uncorrelated) protein-solvent environments. Our approach is based on the framework of the spin-boson model. We derive explicitly the thermal relaxation and decoherence rates of the exciton transfer process, valid for arbitrary temperatures and for arbitrary (in particular, large) interaction constants between the dimer and the environments. We establish a generalization of the Marcus formula, giving reaction rates for dimer levels possibly individually and asymmetrically coupled to environments. We identify rigorously parameter regimes for the validity of the generalized Marcus formula. The existence of long living quantum coherences at ambient temperatures emerges naturally from our approach.

quant-ph↗
arXiv2006

Complex magnetic monopoles and geometric phases around diabolic and exceptional points

We study the geometric phase (GP)in presence of diabolic (DP) and exceptional (EP) points. While the GP associated with the DP is the flux of the Dirac monopole, the GP related to the EP, being complex one, is described by the flux of complex magnetic monopole. For open systems, in week-coupling limit, the leading environment-induced contribution to the real part of complex GP is given by a quadrupole term, and to its imaginary part by a dipolelike field. We find that the GP has a finite gap at the DP and infinite one at the EP.

quant-ph↗
arXiv2002

Towards a new quantization of Dirac's monopole

There are several mathematical and physical reasons why Dirac's quantization must hold. How far one can go without it remains an open problem. The present work outlines a few steps in this direction.

hep-th↗