scholarly journals Entanglement of two dipole-couples qubits induced by a thermal field of a cavity with Kerr medium

2021 ◽  
Vol 24 (3) ◽  
pp. 9-17
Author(s):  
Rodion K. Zakharov ◽  
Evgeny K. Bashkirov
Keyword(s):  
Computer Simulation ◽  
Exact Solution ◽  
Electromagnetic Field ◽  
Density Matrix ◽  
Liouville Equation ◽  
Thermal Field ◽  
Dipole Interaction ◽  
Full Density ◽  
Kerr Medium ◽  
Initial States

In the present work, we investigated the dynamics of two identical superconducting qubits interacting with the mode of the quantum electromagnetic field of a microwave coplanar cavity with a Kerr medium in the presence of an effective dipole-dipole interaction of the qubits. We have found an exact solution of the quantum Liouville equation for the complete density matrix of the system under consideration for the Fock and thermal chaotic initial states of the cavityr field. The exact solution for the full density matrix was used to determine the reduced qubit density matrix and to calculate the entanglement parameter concurrence. Computer simulation of the time dependence of the concurrshowed that for certain initial states of qubits, their entanglement can be significantly increased in the presence of a Kerr medium and direct dipole-dipole interaction.

scholarly journals Entanglement of two dipole-coupled qubits induced by a thermal field of one-mode lossless cavity with Kerr medium

2021 ◽  
Vol 2086 (1) ◽  
pp. 012216
Author(s):  
R K Zakharov ◽  
E K Bashkirov
Keyword(s):  
Exact Solution ◽  
Electromagnetic Field ◽  
Thermal Field ◽  
Kerr Nonlinearity ◽  
Microwave Cavity ◽  
Kerr Medium ◽  
Coupled Qubits

Abstract We studied the dynamics of two qubits interacting with one-mode thermal quantum electromagnetic field of microwave cavity with Kerr medium. Using the exact solution for considered model we derived the qubit-qubit negativity for separa coherent initial qubits states. We showed that initial qubits coherencee interaction can greatly enhance the degree of qubits entanglement in the presence of the Kerr nonlinearity and dipole-dipole interactionyeven for high thermal field intensities.

scholarly journals DYNAMICS OF TWO-LEVEL ATOMS INTERACTING WITH THERMAL FIELD FOR ENTANGLED INITIAL ATOMIC STATES

2017 ◽  
Vol 21 (6) ◽  
pp. 151-160
Author(s):  
E.K. Bashkirov ◽  
A.S. Solovieva ◽  
M.S. Mastyugin
Keyword(s):  
Exact Solution ◽  
Electromagnetic Field ◽  
Density Matrix ◽  
Thermal Field ◽  
Entanglement Dynamics ◽  
Large Intensity ◽  
Atomic States ◽  
And Control ◽  
High Degree ◽  
Degree Of Entanglement

In this paper the entanglement dynamics for system of two two-level atoms interacting with a mode of thermal electromagnetic field in lossless cavity has been investigated. Initial atomic states are the entangled Bell type states. Using the full set of eigenvectors of the Hamiltonian of the considered model we have derived the exact solution for the density matrix for the whole system. On its basis the reduced atomic density matrix and Peres - Horodetcki parameter have been calculated. Calculating of entanglement parameter shows the possibility of high degree of entanglement even for large intensity of thermal field. Thus there is a possibility of maintenance and control over the degree of entanglement.

scholarly journals Atom-atom entanglement in a not-resonant two-photon Tavis-Cummings model

2019 ◽  
Vol 220 ◽  
pp. 03018
Author(s):  
Marya O. Guslyannikova ◽  
Eugene K. Bashkirov
Keyword(s):  
Exact Solution ◽  
Density Matrix ◽  
Thermal Field ◽  
Time Dependent ◽  
Two Photon ◽  
Atomic States ◽  
Dependent Density

The entanglement between two two-level atoms (qubits) interacting not-resonantly with a one mode of thermal field in a lossless cavity via effective degenerate two-photon transitions is investigated. Based on the exact solution for the time-dependent density matrix of the system under consideration, negativity is calculated as a measure of the entanglement of atoms. The influence of a detuning on the dynamics of entanglement of atoms for separable and entangled initial atomic states and thermal cavity state is investigated.

SOME FEATURES OF SQUEEZED NEGATIVE BINOMIAL STATE

1992 ◽  
Vol 06 (03n04) ◽  
pp. 409-415 ◽  
Author(s):  
AMITABH JOSHI ◽  
S. V. LAWANDE
Keyword(s):  
Electromagnetic Field ◽  
Density Matrix ◽  
Wigner Function ◽  
Negative Binomial ◽  
Thermal State ◽  
Photon Number ◽  
Binomial State ◽  
Relationship Of ◽  
The Relationship ◽  
Photon Number Distribution

Properties of electromagnetic field in the squeezed negative binomial state are investigated in terms of photon number distribution and Wigner function. The relationship of the density matrix of the squeezed negative binomial state to the density matrix of the squeezed thermal state is shown explicitly. The possibility of generation of the negative binomial state is also discussed.

Dynamic Stability of an Impact System Connected With Rock Drilling

1969 ◽  
Vol 36 (4) ◽  
pp. 743-749 ◽  
Author(s):  
C. C. Fu
Keyword(s):  
Computer Simulation ◽  
Exact Solution ◽  
Steady State ◽  
Asymptotic Stability ◽  
Piecewise Linear ◽  
Steady State Solution ◽  
External Excitation ◽  
Rock Drilling ◽  
Impact System ◽  
Number Of Cycles

This paper deals with asymptotic stability of an analytically derived, synchronous as well as nonsynchronous, steady-state solution of an impact system which exhibits piecewise linear characteristics connected with rock drilling. The exact solution, which assumes one impact for a given number of cycles of the external excitation, is derived, its asymptotic stability is examined, and ranges of parameters are determined for which asymptotic stability is assured. The theoretically predicted stability or instability is verified by a digital computer simulation.

Dynamics of entanglement and population inversion of two qubits in a hybrid nonlinear system

2021 ◽  
pp. 2150037
Author(s):  
E. M. Khalil ◽  
A.-B. A. Mohamed
Keyword(s):  
Electromagnetic Field ◽  
Nonlinear System ◽  
Analytical Solution ◽  
Nonlinear Interaction ◽  
Population Inversion ◽  
Stark Shift ◽  
Parametric Amplifier ◽  
Kerr Medium ◽  
Interaction Terms

An analytical solution is obtained when the Kerr medium and Stark shift are considered as nonlinear interaction terms to the system containing two-qubit and two-mode electromagnetic field from the parametric amplifier. Dynamics of the population inversion, cavity–qubit and qubit–qubit entanglements are analyzed under the unitary cavity–qubit interaction, the Kerr medium and the Stark shift. The population inversion of a qubit presents periodic revivals and collapses. The results show that the entanglement and the population inversion as well as the inversion have the same stable intervals, that is, the collapse intervals. It is found that the Kerr medium and the Stark shift may lead to reduction of the periods and the amplitudes of the population inversion and the cavity–qubit/qubit–qubit entanglement. The deteriorated qubit–qubit/cavity–qubit entanglement and the population inversion, due to the Kerr medium, may be increased by increasing the Stark shift and vice versa.

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