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A. V. Kuzmin

Publications and source records attributed to A. V. Kuzmin.

17 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↗
arXiv2006

Energy evolution in time-dependent harmonic oscillator with arbitrary external forcing

The classical Hamiltonian system of time-dependent harmonic oscillator driven by the arbitrary external time-dependent force is considered. Exact analytical solution of the corresponding equations of motion is constructed in the framework of the technique (Robnik M, Romanovski V G, J. Phys. A: Math. Gen. {\bf 33} (2000) 5093) based on WKB approach. Energy evolution for the ensemble of uniformly distributed w.r.t. the canonical angle initial conditions on the initial invariant torus is studied. Exact expressions for the energy moments of arbitrary order taken at arbitrary time moment are analytically derived. Corresponding characteristic function is analytically constructed in the form of infinite series and numerically evaluated for certain values of the system parameters. Energy distribution function is numerically obtained in some particular cases. In the limit of small initial ensemble's energy the relevant formula for the energy distribution function is analytically derived.

nlin.SI↗
arXiv2006

On connection between purity and fidelity of quantum channels

Quantum channels depending on a number of classical control parameters are considered. Assuming the stochastic fluctuations of the control parameters in the small errors limit it is shown that the channel fidelity is equal to the average value of the channel purities calculated in the cases of the control errors presence and absence respectively. The result validity is demonstrated on two particular examples, namely, one-qubit quantum gates implemented in the framework of the ion trap setup and the single qubit anisotropic depolarizing quantum channel.

quant-ph↗
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↗
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↗
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↗
arXiv2003

Chaos assisted instanton tunneling in one dimensional perturbed periodic potential

For the system with one-dimensional spatially periodic potential we demonstrate that small periodic in time perturbation results in appearance of chaotic instanton solutions. We estimate parameter of local instability, width of stochastic layer and correlator for perturbed instanton solutions. Application of the instanton technique enables to calculate the amplitude of the tunneling, the form of the spectrum and the lower bound for width of the ground quasienergy zone.

nlin.CD↗
arXiv2003

Coherent Tunneling and Instantons in Presence of Classical Chaos

We consider the instanton approach to the problem of chaos assisted tunneling in the context of existing analytical and numerical results obtained in this field. We provide the estimation for the range of validity of this method and briefly discuss possible applications of chaos assisted tunneling for quantum computations.

nlin.CD↗
arXiv2002

Quantum field fluctuations and chaotic dynamics of model 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.

hep-th↗
arXiv2002

Towards chaos criterion in quantum field theory

Chaos criterion for quantum field theory is proposed. Its correspondence with classical chaos criterion in semi-classical regime is shown. It is demonstrated for real scalar field that proposed chaos criterion can be used to investigate stability of classical solutions of field equations.

hep-th↗