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E. A. Ivanchenko

Publications and source records attributed to E. A. Ivanchenko.

10 recordsLinked to original sources
arXiv2017

Quantum speed limit time in a magnetic resonance

A visualization for dynamics of a qudit spin vector in a time-dependent magnetic field is realized by means of mapping a solution for a spin vector on the three-dimensional spherical curve (vector hodograph). The obtained results obviously display the quantum interference of precessional and nutational effects on the spin vector in the magnetic resonance. For any spin the bottom bounds of the quantum speed limit time (QSL) are found. It is shown that the bottom bound goes down when using multilevel spin systems. Under certain conditions the non-nil minimal time, which is necessary to achieve the orthogonal state from the initial one, is attained at spin S=2. An estimation of the product of two and three standard deviations of the spin components are presented. We discuss the dynamics of the mutual uncertainty, conditional uncertainty and conditional variance in terms of spin standard deviations. The study can find practical applications in the magnetic resonance, 3D visualization of computational data and in designing of optimized information processing devices for quantum computation and communication.

quant-ph↗
arXiv2016

Visualization of Rabi oscillations in a magnetic resonance

A visualization scheme for dynamics of a qudit polarization vector in a time-dependent magnetic field is presented by solving equations for a density matrix in Hermitian basis. This is realized by means of mapping solution for the polarization vector on the three-dimensional spherical curve (vector hodograph). The obtained results obviously display the interference of precessional and nutational effects on the polarization vector in a magnetic resonance. The study can find the practical applications in a magnetic resonance and 3D visualization of computational data.

quant-ph↗
arXiv2015

Quantum Otto cycle efficiency on coupled qudits

Properties of the coupled particles with spin 3/2 (quartits) in a constant magnetic field, as a working substance in the quantum Otto cycle of the heat engine, are considered. It is shown that this system as a converter of heat energy in work (i) shows the efficiency 1 at the negative absolute temperatures of heat baths, (ii) at the temperatures of the opposite sign the efficiency approaches to 1, (iii) at the positive temperatures of heat baths antiferromagnetic interaction raises efficiency threefold in comparison with uncoupled particles.

quant-ph↗
arXiv2013

Entanglement dynamics in finite qudit chain in consistent magnetic field

Based on the Liouville-von Neumann equation, we obtain a closed system of equations for the description of a qutrit or coupled qutrits in an arbitrary, time-dependent, external magnetic field. The dependence of the dynamics on the initial states and the magnetic field modulation is studied analytically and numerically. We compare the relative entanglement measure's dynamics in bi-qudits with permutation particle symmetry. We find the magnetic field modulation which retains the entanglement in the system of two coupled qutrits. Analytical formulae for the entanglement measures in finite chains from 2 to 6 qutrits or 3 quartits are presented.

quant-ph↗
arXiv2011

Non-equilibrium reversible dynamics of work production in four-spin system in a magnetic field

A closed system of the equations for the local Bloch vectors and spin correlation functions is obtained by decomplexification of the Liouville-von Neumann equation for 4 magnetic particles with the exchange interaction that takes place in an arbitrary time-dependent external magnetic field. The analytical and numerical analysis of the quantum thermodynamic variables is carried out depending on separable mixed initial state and the magnetic field modulation. Under unitary evolution, non-equilibrium reversible dynamics of power production in the finite environment is investigated.

cond-mat.stat-mech↗
arXiv2011

Qutrit: entanglement dynamics in the finite qutrit chain in the consistent magnetic field

Based on the Liouville-von Neumann equation, we obtain closed system of equations for the description of a qutrit or coupled qutrits in arbitrary time-dependent external magnetic field. The dependence of the dynamics on the initial states and magnetic field modulation is studied analytically and numerically. We compare the relative entanglement measure's dynamics in the bi-qutrit system with permutation particle symmetry. We find the magnetic field modulation which retains the entanglement in the system of two coupled qutrits. Analytical formulas for entanglement measures in the chain from 2 to 6 qutrits are presented.

quant-ph↗
arXiv2009

Dynamic equations for three different qudits in a magnetic field

A closed system of equations for the local Bloch vectors and spin correlation functions of three magnetic qudits, which are in an arbitrary, time-dependent, external magnetic field, is obtained using decomplexification of the Liouville-von Neumann equation. The algorithm of the derivation of the dynamic equations is presented. In the basis convenient for the important physical applications structure constants of algebra su(2S+1) are calculated.

quant-ph↗
arXiv2006

Three-qubit dynamics of entanglement in magnetic field

A closed system of the equations for the local Bloch vectors and spin correlation functions is obtained by decomplexification of the Liouville-von Neumann equation for three magnetic qubits with the exchange interaction, that takes place in an arbitrary time-dependent external magnetic field. The numerical comparative analysis of entanglement is carried out depending on initial conditions and the magnetic field modulation. The present study may be useful for analysis of interference experiments and in the field of quantum computing.

quant-ph↗
arXiv2004

Magnetic resonance in an elliptic magnetic field

The behaviour of a particle with a spin 1/2 and a dipole magnetic moment in a time-varying magnetic field in the form $(h_0 cn(ωt,k), h_0 sn(ωt,k), H_0 dn(ωt,k))$, where $ω$ is the driving field frequency, $t$ is the time, $h_0$ and $H_0$ are the field amplitudes, $cn$, $sn$, $dn$ are Jacobi elliptic functions, $ k$ is the modulus of the elliptic functions has been considered. The variation parameter $k$ from zero to 1 gives rise to a wide set of functions from trigonometric shapes to exponential pulse shapes modulating the field. The problem was reduced to the solution of general Heun' equation. The exact solution of the wave function was found at resonance for any $ k$. It has been shown that the transition probability in this case does not depend on $k$. The present study may be useful for analysis interference experiments, improving magnetic spectrometers and the field of quantum computing.

quant-ph↗