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1.
The possible existence of so-called “squeezed” states in two-atom resonance fluorescence is discussed in Lehmberg's master equation approach. It is shown that squeezing strongly depends on interatomic separations r12. For large r12 one of the quadrature components is squeezed, and as r12 decreases its squeezing decreases in order to appear in the other quadrature component for certain value of r12. For very small r12 fluctuations in both components tend to zero. 相似文献
2.
This paper proposes a decoherence-immune scheme for
generating highly entangled states for two atoms trapped in a cavity.
The scheme is based on two resonant atom-cavity interactions.
Conditional upon the detection of no photon, the two atoms may
exchange an excitation via the first resonant interaction, which
leads to entanglement. Due to the loss of the excitation, the two
atoms are in a mixed entangled state. With the help of an auxiliary
ground state not coupled to the cavity mode, the state related to
the excitation loss is eliminated by the detection of a photon
resulting from the second resonant interaction. Thus, the fidelity
of entanglement is almost not affected by the decoherence. 相似文献
3.
Summary The binding energy for on-centre impurities in a rectangular quantum well wire is calculated as a function of the width of
the wire and perpendicular magnetic field. The results for zero-magnetic-field case are in perfect agreement with previous
calculations.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
4.
The dynamics of appearance of a steady entangled state in an ensemble of two collectively decaying two-level atoms is studied on the basis of the Peres-Horodecki criterion with regard to the dipole-dipole interaction between the atoms and their frequency detuning. It is ascertained that, in the absence of dipole-dipole interaction, the steady-state entanglement is in many respects due to the coincidence of the frequencies of transitions in the atoms, whereas a difference in the frequencies, related to different positions of the atoms in a crystal or their thermal motion, destroys the steady-state entanglement. Upon a dipole-dipole interaction, a steady-state entanglement also exists and, in this case, depends strongly on the relationship between the magnitude of the dipole-dipole interaction, the constant of coupling with a thermostat, and the phase of the resonance wave; the entanglement appears only when the thermostat coupling constant is dominant. 相似文献
5.
In this paper a scheme is proposed for the purification of entangled states for two atoms trapped in two distant cavities via cavity decay. In the scheme, the atoms have no probability of being populated in the excited state and thus the atomic spontaneous emission is suppressed. This scheme is valid no matter when the cavity decay rate is larger or smaller than the effective atom-cavity coupling strength. The fidelity of the final state is not affected by the imperfection of the photodetectors. 相似文献
6.
Two identical dipole-dipole interacting two-level atoms in a nonideal cavity are considered at a nonzero temperature. The radiation line profile is calculated within the quantum relaxation theory as a function of the interatomic distance and an exact analytical expression for this profile is obtained. 相似文献
7.
G. Schaack 《Solid State Communications》1975,17(4):505-509
Raman scattering experiments in paramagnetic uniaxial CeF3 at helium temperature demonstrate a splitting of some degenerate (Eg)-phonon states in an external magnetic field parallel to the crystal axis. A linear splitting is observed in low fields, followed by a field independent (saturation) splitting in high fields. In addition, changes in the Raman scattering efficiencies and a reduction of the line width of phonon transitions are observed with increasing magnetic fields. No such effects are observed for magnetic fields perpendicular to the crystal axis. The splittings of degenerate phonon modes are related to the paramagnetic saturation 〈Sz〉. 相似文献
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10.
We investigate the entanglement in a system of two coupling atoms
interacting with a single-mode field
by means of quantum information entropy theory.
The quantum entanglement between the two atoms and the coherent field is discussed by using
the quantum reduced entropy,
and the entanglement between the two coupling atoms is also investigated
by using the quantum relative entropy.
In addition, the influences of the atomic dipole--dipole interaction
intensity and
the average photon number of the coherent field on the degree of the entanglement is examined.
The results show that the evolution of the degree of entanglement between the two atoms
and the field is just opposite to that of the degree of entanglement between the two atoms.
And the properties of the quantum entanglement in the system rely on the
atomic dipole--dipole
interaction and the average photon number of the coherent field. 相似文献
11.
12.
Jamal T. Manassah 《Laser Physics》2010,20(6):1397-1403
The values of the radii of the sphere enclosing an ensemble of two-level atoms corresponding to metastable states in the cooperative
emission are computed. The dynamics of these states and, in particular, the delay in the maximum of the emission intensity
are given for the different orders of the critical radii. 1 The article is published in the original. 相似文献
13.
V. A. Gunyakov S. A. Myslivets A. M. Parshin V. Ya. Zyryanov V. G. Arkhipkin V. F. Shabanov 《Technical Physics》2010,55(10):1484-1489
The method of modulation of transmittance of a multilayer photonic crystal with a nematic liquid-crystal defect upon the orientational transition from the homeotropic to the planar state is investigated. The orientation of the director of the nematic is controlled by a magnetic field in the B-effect mode. The method of recurrent relations is used for numerical simulation of transmission spectra of the photonic crystal structure under investigation. 相似文献
14.
Entanglement between two atoms in the system of SchrSdinger cat state interacting with two entangled atoms
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By the negative eigenvalues of partial transposition of density matrix, this paper investigates the time evolution of entanglement of the two entangled atoms in the system of two atoms interacting with SchrSdinger cat state. The result shows that the two atoms are always in the entanglement state, and the degree of entanglement between the two atoms exhibits ordinary collapses and revivals at 0.2 degree of entanglement, when the light field is large enough. On the other hand, the reinforcement of three different light fields on the degree of entanglement between two atoms is not evident.[第一段] 相似文献
15.
E. A. Gazazyan A. D. Gazazyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2016,51(2):127-135
Using the Dirac’s method, the formation of metastable molecular states at the resonance scattering of two atoms in the laser radiation field is considered. Expressions for the metastable level populations and the resonance scattering cross sections are obtained. In the case of an exact resonance with the laser radiation, the graphs for populations and resonance scattering cross sections, which have two peaks due to the Autler–Townes effect, are obtained. These results play an important role in the study of the controlled chemical reaction and for the understanding of the processes in the quantum systems of the Bose–Einstein condensate at low temperatures, as well as in the various optical processes in atomic gases. 相似文献
16.
Kurumaji T Seki S Ishiwata S Murakawa H Tokunaga Y Kaneko Y Tokura Y 《Physical review letters》2011,106(16):167206
Magnetic and dielectric properties with varying magnitude and direction of magnetic-field H have been investigated for a triangular-lattice helimagnet MnI_{2}. The in-plane electric polarization P emerges in the proper screw magnetic ground state below 3.5 K, showing the rearrangement of six possible multiferroic domains as controlled by the in-plane H. With every 60° rotation of H around the [001] axis, discontinuous 120° flop of the P vector is observed as a result of the flop of magnetic modulation vector q. With increasing the in-plane H above 3 T, however, the stable q direction changes from q‖(110[ ˉover 0]) to q‖(110), leading to a change of P-flop patterns under rotating H. At the critical field region (~3 T), due to the phase competition and resultant enhanced q flexibility, the P vector smoothly rotates clockwise twice while the H vector rotates counterclockwise once. 相似文献
17.
A stationary solution is obtained for the joint system of equations for atomic and field variables for two different atoms with dipole-dipole interaction in the radiation field taking into account the common radiative friction. The atoms are treated as an Lorentz oscillator with one isolated resonance. The interaction of atoms in the radiation field forms four dimensional resonances at frequencies that are substantially different from the natural frequencies of isolated atoms. Two of the four dimensional resonances are characterized by negative dispersion, and the intensity of dipole emission at these frequencies may be increased with respect to the intensity of emission at the frequencies of natural atomic resonances by a factor of about 1012. 相似文献
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Dicke superradiance has been observed in many systems and is based on constructive interferences between many scattered waves. The counterpart of this enhanced dynamics, subradiance, is a destructive interference effect leading to the partial trapping of light in the system. In contrast to the robust superradiance, subradiant states are fragile, and spurious decoherence phenomena hitherto obstructed the observation of such metastable states. We show that a dilute cloud of cold atoms is an ideal system to look for subradiance in free space and study various mechanisms to control this subradiance. 相似文献