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V. I. Kuvshinov

Publications and source records attributed to V. I. Kuvshinov.

At least 19 recordsLinked to original sources
arXiv2011

Asymmetric double well system as effective model for the kicked one

Effective Hamiltonian for the kicked double well system was derived using the Campbell-Baker-Hausdorff expansion formula. Asymmetric model for the kicked system was constructed. Analytical description of the quasienergy levels splittings for the low laying doublets was given in the framework of the model. Numerical calculations confirm applicability of the proposed effective asymmetric approach for the double well system with the kick-type perturbation.

nlin.CD↗
arXiv2011

Chaotic instantons and enhancement of tunneling in double-well system with polychromatic perturbation

Chaotic instanton approach allows to describe analytically the influence of the polychromatic perturbation on quantum properties of nonlinear systems. Double well system with single, multiple and polychromatic kicked perturbation is considered in the paper to compare quantitative analytical predictions with the results of numerical calculations. Chaotic instantons are responsible for the enhancement of tunneling far away from the exact (avoided) level crossings in framework of the approach used. Time-independent averaged system is used for regular approximation of the chaotic instanton solution in order to take into account its contribution to the ground quasienergy doublet splitting. Formula for the ground quasienergy levels' splitting was derived averaging trajectory action in the stochastic layer in the framework of chaotic instanton approach. Results of quasienergy spectrum numerical calculations and simulations for tunneling dynamics are in good agreement with the obtained analytical predictions.

nlin.CD↗
arXiv2010

Chaotic instantons and enhancement of tunneling in kicked double-well system with time-reversal symmetry

Chaotic instanton approach is used to describe dynamical tunneling in kicked double well system. Effective Hamiltonian for the kicked system is obtained using matrix expansion formula for operator exponent and exploited to construct an approximation for chaotic instanton solution. This approximation is used for derivation of the ground quasienergy splitting dependence on both the perturbation strength and frequency. Results of numerical calculations for corresponding ground quasienergy splitting dependencies based on Floquet theory are in good agreement with the derived analytical formula in a wide range of perturbation parameters.

nlin.CD↗
arXiv2008

Chaotic instantons in periodically perturbed double-well system

Kicked double-well system is investigated both analytically and numerically. Phenomenological formula for ground quasienergy splitting is obtained using resonances overlap criterion in the framework of chaotic instanton approach. Results of numerical calculations of quasienergy spectrum are in good agreement with the phenomenological formula.

nlin.CD↗
arXiv2007

Stability of Yang-Mills fields system in the homogeneous (anti-)self-dual background field

Stability of Yang-Mills fields system in the background field is investigated basing on Toda criterion, Poincare sections and the values of the maximal Lyapunov exponents. The existence of the region of regular motion at low densities of energy is demonstrated. Critical energy density of the order-chaos transition is analyzed for the different values of the model parameter.

nlin.CD↗
arXiv2006

Mixed colour states in QCD confining vacuum

We show that confinement of spinless heavy quarks in fundamental representation of $SU(N_{c})$ gauge group can be treated as decoherence of pure colour state into a white mixture of states. Decoherence rate is found to be proportional to the tension of QCD string and the distance between colour charges. The purity of colour states is calculated.

hep-th↗
arXiv2006

Kramers-Moyall cumulant expansion for the probability distribution of parallel transporters in quantum gauge fields

A general equation for the probability distribution of parallel transporters on the gauge group manifold is derived using the cumulant expansion theorem. This equation is shown to have a general form known as the Kramers-Moyall cumulant expansion in the theory of random walks, the coefficients of the expansion being directly related to nonperturbative cumulants of the shifted curvature tensor. In the limit of a gaussian-dominated QCD vacuum the obtained equation reduces to the well-known heat kernel equation on the group manifold.

hep-th↗
arXiv2006

Asymptotic behavior of Wilson loops from Schroedinger equation on the gauge group

Probability distribution of non-Abelian parallel transporters on the group manifold and the corresponding amplitude are investigated for quantum Yang-Mills fields. It is shown that when the Wilson area law and the Casimir scaling hold for the quantum gauge field, this amplitude can be obtained as the solution of the free Schroedinger equation on the gauge group. Solution of this equation is written in terms of the path integral and the corresponding action term is interpreted geometrically. We also note that the partition function of two-dimensional pure Yang-Mills theory living on the surface spanned on the loop solves the obtained equation.

hep-th↗
arXiv2006

Decoherence induced by squeezing control errors in optical and ion trap holonomic quantum computations

We study decoherence induced by stochastic squeezing control errors considering the particular implementation of Hadamard gate on optical and ion trap holonomic quantum computers. We find the fidelity for Hadamard gate and compute the purity of the final state when the control noise is modeled by Ornstein-Uhlenbeck stochastic process. We demonstrate that in contradiction to the case of the systematic control errors the stochastic ones lead to decoherence of the final state. In the small errors limit we derive a simple formulae connecting the gate fidelity and the purity of the final state.

quant-ph↗
arXiv2006

Fidelity of holonomic quantum computations in the case of random errors in the values of control parameters

We investigate the influence of random errors in external control parameters on the stability of holonomic quantum computation in the case of arbitrary loops and adiabatic connections. A simple expression is obtained for the case of small random uncorrelated errors. Due to universality of mathematical description our results are valid for any physical system which can be described in terms of holonomies. Theoretical results are confirmed by numerical simulations.

quant-ph↗
arXiv2005

Robust Hadamard gate for optical and ion trap holonomic quantum computers

We consider one possible implementation of Hadamard gate for optical and ion trap holonomic quantum computers. The expression for its fidelity determining the gate stability with respect to the errors in the single-mode squeezing parameter control is analytically derived. We demonstrate by means of this expression the cancellation of the squeezing control errors up to the fourth order on their magnitude.

quant-ph↗
arXiv2005

Fidelity and Wilson loop for quarks in confinement region

Connection between the stability of quantum motion in random fields and quark confinement in QCD is investigated. The analogy between the fidelity and the Wilson loop is conjectured, and the fidelity decay rates for different types of quark motion are expressed in terms of the parameters which are commonly used in phenomenological and lattice QCD.

hep-th↗
arXiv2005

Fidelity, quantum computations and Wilson loop

General properties of quantum systems which interact with stochastic environment are studied with a strong emphasis on the role of physical symmetries. The similarity between the fidelity which is used to characterize the stability of such a systems and the Wilson loop in QCD is demonstrated, and the fidelity decay rates are derived. The consequences of existence of the symmetry group on the statistical properties of the system are analyzed for various physical systems - a simple quantum mechanical system, holonomic quantum computer and Yang-Mills fields.

hep-th↗
arXiv2003

Deterministic Chaos in Quantum Field Theory

We discuss the necessity and demonstrate the validity of introduction the notion of deterministic chaos in quantum field theory. Brief review of the existing approaches to this problem is given. We compare proposed chaos criterion for quantum fields with existing ones. Its consequences in particle physics are also discussed.

nlin.CD↗
arXiv2003

Stability of holonomic quantum computations

We study the stability of holonomic quantum computations with respect to errors in assignment of control parameters. The general expression for fidelity is obtaned. In the small errors limit the simple formulae for the fidelity decrease rate is derived.

quant-ph↗
arXiv2003

The influence of quantum field fluctuations on chaotic dynamics of Yang--Mills system

On example of the model field system we demonstrate that quantum fluctuations of non-abelian gauge fields leading to radiative corrections to Higgs potential and spontaneous symmetry breaking can generate order region in phase space of inherently chaotic classical field system. We demonstrate on the example of another model field system that quantum fluctuations do not influence on the chaotic dynamics of non-abelian Yang--Mills fields if the ratio of bare coupling constants of Yang--Mills and Higgs fields is larger then some critical value. This critical value is estimated.

nlin.CD↗