An exact solution of the problem of two two-level atoms with degenerate Raman two-photon transitions interacting with one-mode coherent or thermal radiation field in cavity is presented. Asymptotic solution for system state vector is obtained in the approximation of large initial coherent fields. The atom-field is investigated on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure disentangled state to revive into this state during the evolution process is shown. Conditions and times of disentanglement are derived. The atom-atom entanglement is investigated with using negativity. The possibility of sudden death and birth of atom-atom entanglement is predicted for a coherent field with large mean photon numbers.
In this paper, we have investigated the entanglement dynamics between two initially entangled superconducting qubits in the framework of a double Jaynes-Cummings model with different atom-filed coupling constants and detunings taking into account the direct dipole-dipole interaction. We have carried out the dependence of the atom-atom entanglement on the strength of the dipole-dipole interaction and other parameters of the considered system such as the different coupling constants and the detunings. The results show these parameters have great impact on the amplitude and the period of the atom-atom entanglement evolution. In addition, the presence of sufficiently large dipole-dipole interaction leads to stabilization of entanglement for all Bell-types initial qubits states and different couplings and detunings.
Proc. SPIE. 10337, Saratov Fall Meeting 2016: Laser Physics and Photonics XVII; and Computational Biophysics and Analysis of Biomedical Data III
KEYWORDS: Data modeling, Computing systems, Control systems, Telecommunications, Solids, Quantum mechanics, Entangled states, Quantum communications, Quantum information theory
The entanglement between two identical two-level atoms successively passing the thermal cavity has been investigated taking into account the detuning. The case when atoms are initially prepared in the Bell types entangled atomic states has been considered. It has been shown that for vacuum state of the cavity the presence of detuning leads to decreasing of the entanglement amplitude oscillations. We have also derived that for thermal field the increasing of the mean photon number leads to decreasing of the entanglement, but the entanglement increases as the detuning increases. For thermal field and small detuning we have established that the effect of sudden death and birth of entanglement takes place and that for large detuning such effect vanishes.
Proc. SPIE. 9917, Saratov Fall Meeting 2015: Third International Symposium on Optics and Biophotonics and Seventh Finnish-Russian Photonics and Laser Symposium (PALS)
KEYWORDS: Chemical species, Superconductors, Physics, Control systems, Telecommunications, Solids, Quantum physics, Entangled states, Quantum information, Quantum communications
We study the entanglement properties of a pair of two-level atoms going through a thermal cavity one after another. The initial joint states of two successive atoms that enter the cavity are coherent or entangled. Using the exact solution of density matrix evolution equation we calculated the negativity for different values of cavity mean photon numbers. We shown the possibility to save the initial atomic entanglement even for a thermal cavity field with relatively high temperature.
Proc. SPIE. 9917, Saratov Fall Meeting 2015: Third International Symposium on Optics and Biophotonics and Seventh Finnish-Russian Photonics and Laser Symposium (PALS)
KEYWORDS: Superposition, Chemical species, Solids, Electromagnetism, Entangled states, Thermal modeling, Quantum information, Quantum communications, Quantum computing, Tin
We have investigated the influence of dipole-dipole interaction and initial atomic coherence on atomic entanglement dynamics of two qubits. We have considered a model, in which only one atom couples to a quantum electromagnetic field in a cavity, since one of them can move around the cavity. We have shown that the entanglement arises for all pure atomic state even when both atoms are initially in the excited states. We have also derived that degree of entanglement is enhanced in the presence of the atomic coherence.
Proc. SPIE. 9917, Saratov Fall Meeting 2015: Third International Symposium on Optics and Biophotonics and Seventh Finnish-Russian Photonics and Laser Symposium (PALS)
KEYWORDS: Chemical species, Particles, Photons, Superconductors, Solids, Electromagnetism, Entangled states, Quantum information, Quantum communications, Quantum information processing
We investigated the entanglement dynamics in a quantum system consisting of three two-level atoms resonantly coupled to a single mode electromagnetic field. We considered the dynamics of the system under consideration for Fock and thermal initial cavity states. An explicit analytical solution of the system has been obtained and the entanglement has been studied with the help of the two-qubit negativity. It was also shown that for both initial cavity states the sudden death of two-qubit entanglement takes place.
Proc. SPIE. 9448, Saratov Fall Meeting 2014: Optical Technologies in Biophysics and Medicine XVI; Laser Physics and Photonics XVI; and Computational Biophysics
KEYWORDS: Superposition, Chemical species, Physics, Solids, Electromagnetism, Entangled states, Systems modeling, Quantum information, Quantum communications, Quantum cryptography
We have investigated the influence of dipole-dipole interaction and initial atomic coherence on dynamics of two-atom systems. We have considered a model, in which only one atom is trapped in a cavity, and the other one can be spatially moved freely outside the cavity. We have shown the possibility of disappearance of the entanglement sudden death effect in the presence of the dipole interaction of atoms. We have also derived that the initial atomic coherence can be used for effective control of the degree of the atom-atom entanglement.
Proc. SPIE. 9448, Saratov Fall Meeting 2014: Optical Technologies in Biophysics and Medicine XVI; Laser Physics and Photonics XVI; and Computational Biophysics
KEYWORDS: Oscillators, Surgery, Chemical species, Physics, Solids, Optical resonators, Four wave mixing, Barium, Electromagnetism, Systems modeling
Squeezing for one- and two-mode two-atom Jaynes-Cummings model with intensity-dependent coupling has been investigated assuming the field to be initially in the coherent state. The time-dependent squeezing parameters have been calculated. The influence of the intensity of the cavity field and initial atomic state on the squeezing parameters has been analyzed.
Proc. SPIE. 9448, Saratov Fall Meeting 2014: Optical Technologies in Biophysics and Medicine XVI; Laser Physics and Photonics XVI; and Computational Biophysics
In this paper we have investigated the atom-atom entanglement for degenerate two-photon Tavis-Cummings model with taking into account Stark shift and initial atomic coherence. Considering different initial coherent states we have derived that the atom-atom entanglement can be greatly increased or decreased due to the presence of the Stark shift. In addition, we have derived that the entanglement sudden death effect vanishes due to the presence of Stark shift for some initial states.
The entanglement of two dipole-coupled superconducting flux qubits with degenerate two-photon transitions
interacting with one-mode superconducting LC circuit has been investigated. The possibility of considerable
growth of atomic entanglement due atomic coherence and dipole-dipole interaction has been shown.
The entanglement of two dipole-coupled superconducting flux qubits with degenerate and nondegenerate twophoton transitions interacting with one-mode or two-mode field in lossless cavity has been investigated. The influence of dipole-dipole interaction on the entanglement between two qubits for different initial atom-field entangled states has been considered. The results show that the entanglement between two artificial atoms can be increased by means of dipole-dipole interaction and for some initial states the entanglement sudden death effect can be weakened.
An exact solution of the problem of two two-level atoms with nondegenerate two-photon transitions and intensitydependent
coupling interacting with two-mode radiation field is presented. Asymptotic solution for system state
vector is obtained in the approximation of large initial coherent fields. The atom-field entanglement is investigated
on the basis of the reduced atomic entropy dynamics. The possibility of the system being initially in a pure
disentangled state to revive into this state during the evolution process is shown. Conditions and times of
disentanglement are derived.
The entanglement between two identical two-level atoms successively passing thermal cavity and interacting with
one-mode thermal field through a degenerate two-photon process is investigated. It is shown that two atoms can
be entangled through such nonlinear interaction.
The entanglement of two dipole-coupled atoms with nondegenerate two-photon transitions interacting with twomode
field in lossless cavity has been investigated. It shows that the entanglement is dependent on the initial
atomic states. The possibility of considerable growth of atomic entanglement due atomic coherence and dipoledipole
interaction is shown in the case of great mean values of thermal photons.
The exact wave function is found in the work for the two-atom models with nondegenerate two-photon interaction
and nondegenerate raman interaction. The asymptotic solutions for system state vectors are obtained in the
approximation of strong field for considered models for different initial atom states and coherent field input.
The reduced entropy dynamics is described for various initial atomic states and coherent field input, some
conclusions about atom-field entanglement are made. We also show the possibility for the system being initially
in the pure nonentangled state to revive into this state during the evolution process for the two-atom model with
nondegenerate two-photon interaction and we obtain the times of such revivals.
In this article the interaction of two nonidentical two-level atoms with one mode of the electromagnetic field has
been considered. The pure-state evolution of the atomic states for field initially in the coherent state and atoms
in the ground state has been investigated. The possibility of the maximally entangled states at the beginning of
the collapse time has been discussed.
The exact wave function and asymptotic expressions for the system state vectors under strong initial coherent
fields are found in the work for the two-atom models with nondegenerate two-photon interaction and nondegen-
erate Raman interaction. The atom-field entanglement is considered via linear entropy criterion. The system
revivals to unentangled states are shown to appear for both models. The disentanglement times are derived in
the work. The atom-atom entanglement induced by thermal noise is investigated for the both models.
The entropy dynamics for three-level Ξ-type atom is investigated in the article. The analytic expressions for atomic
entropy are obtained in the work, as well as exact solutions for Schr&diaero;dinger equation for wave function. The
entanglement dynamics in the system is considered on the base of reduced entropy analysis.
Proc. SPIE. 6537, Saratov Fall Meeting 2006: Laser Physics and Photonics, Spectroscopy and Molecular Modeling VII
KEYWORDS: Atrial fibrillation, Chemical species, Complex systems, Physics, Photonics systems, Chemical elements, Electromagnetism, Systems modeling, Quantum information, Correlation function
In this work we considered temporal behaviour of a two two-level atoms in a infinite-Q cavity with atom dissipation
for coherent and squeezed inputs. The analytic expressions for second-order correlation function and squeezing
parameters and amplitude-squeezing parameters are obtained on the basis of master equation solution. System
observables dynamics is investigated for coherent and squeezed initial field state for various system parameters values.
In this work we considered temporal behavior of squeezing and amplitude-squared squeezing for a two two-level
atoms in a finite-Q cavity with atom dissipation. The analytic expressions for squeezing parameters are obtained
on the basis of master equation solution for coherent and squeezed input. Squeezing generation conditions are
considered for various dissipation parameters values and coherent and squeezed initial input.
The entanglement between two unidentical two-level atoms with different frequencies interacting with one-mode
thermal field in lossles cavity has been investigated. The role of detuning in this effect has been carried out.
The kinetics of the extended model of crystal doped by rare-earth ions in regime of anti-Stokes laser cooling
has been considered taking into account the collective radiation effects. The system of master equations for
impurities and pseudo-local phonons has been obtained. As would be expected, the collective radiation effects
causes an acceleration in relaxation depletion of the phohon mode and therefore an increase of crystal cooling
efficiency.
Proc. SPIE. 6165, Saratov Fall Meeting 2005: Laser Physics and Photonics, Spectroscopy and Molecular Modeling VI
KEYWORDS: Chemical species, Spectroscopy, Physics, Computer science, Photonics, Molecular spectroscopy, Chemical elements, Electromagnetism, Information operations, Correlation function
A nondegenerate two-photon Jaynes-Cummings model is investigated where the leakage of photon through the
cavity is taken into account. The effect of cavity damping on the mean photon number, atomic populations,
field statistics and both field and atomic squeezing is considered on the basis of master equation in dressed-state
approximation for initial coherent fields and excited atom.
The entanglement between two identical two-level atoms interacting with two mode thermal field through a nondegenerate two-photon process has been suggested. The role of detuning has been illustrated by the example of simple one-mode two-atom model.
The collective spontaneous radiation of the macroscopic system of V-type three-level atoms interacting with quantum electromagnetic field and coherent pumping field has been investigated on the basis of the Bogolubov's method of the elimination ofthe boson variables. The possibility of the subradiant and superradiant regimes in dependence of the pumping area has been established.
The dynamics of detuned two-level Jaynes-Cummings model with multiphoton transitions in the finite Q-cavity has been considered. The time evolution of the mean photon number and atomic populations has been investigated for various values of the model parameters. The type of field statistics and photon bunching/antibunching effects has been examined.
On the basis of the master equation for the density matrix the dynamics of the collective spontaneous radiation of two Λ - type three-level atoms interacting with two modes of quantum electromagnetic field in the damped cavity has been considered. The behaviour of the photon numbers in modes has been investigated in the case when both atoms are in excited state at the initial time.
On the basis of the master equation for the density matrix the dynamics of the collective spontaneous radiation of two (Lambda) - type three-level atoms interacting with two mode of quantum electromagnetic field in the damped cavity has been considered. The behavior of the photon numbers in modes and the atomic levels populations has been investigated in the case when only a single atom is excited at the initial time.
On the basis of the master equation for the density matrix the dynamics of the three-level atom interacting with two mode of quantum electromagnetic field in the damped cavity has been considered. The behavior of the mean populations of the atomic levels and photon numbers in modes has been investigated.
The chain of kinetic equations for three-level macroscopic systems intersecting with an electromagnetic field on the basis of then method of elimination of the boson variables is obtained. On its basis the role of two-photon transitions is investigated.
The chain of kinetic equations for two-level and three-level macroscopic systems, interacting with the electromagnetic field, is obtained on the basis of the method of elimination of the boson variables, taking a new type of decoupling for three-particle correlators into account. These equations yield a better description of experimentally observed shape of super-radiant pulse than the standard theories based on the decoupling of the Tyablyakov's type.
The chain of kinetic equations for a three-level extended macroscopic system interacting with an electromagnetic field is obtained on the basis of the method of elimination of the boson variables taking into account the coherent pumping processes. On its basis the conventional superradiance of the system is examined in the markovian limit. The relations between the parameters of the superradiant pulse and those of the pumping pulse of arbitrary duration are obtained. The possibility of description of the triggering superradiance is discussed.
Kinetics of superradiance for a system of two-level emitters interacting with the quantum electromagnetic field is studied. A closed set of equations for atomic correlation functions is obtained which takes into account new decoupling of three- particle correlators. These equations yield a better description of experimentally observed shape of superradiant peak than the standard theories.
Initial conditions corresponding to the stationary evolution of a two-mode two-boson model with interaction between modes and self- action in one of them have been considered. On this basis the possibility of the steady squeezing for both Bose fields has been established. The estimations of the squeezing parameters have been obtained.