共查询到20条相似文献,搜索用时 27 毫秒
1.
Faisal A. A. El-Orany S. Abdel-Khalek M. Abdel-Aty M. R. B. Wahiddin 《International Journal of Theoretical Physics》2008,47(5):1182-1194
In this paper, we study the interaction between the two-level atom and a bimodal cavity field, namely, two-mode Jaynes–Cummings
model when the atom and the modes are initially in the atomic superposition state and two-mode squeezed vacuum state, respectively.
For this system we investigate the atomic inversion, linear entropy and atomic Wehrl entropy. We show that there is a connection
between all these quantities. Also we prove that the atomic Wehrl entropy exhibits behaviors similar to those of the linear
entropy and the von Neumann entropy. Moreover, we show that the bipartite exhibits periodical disentanglement and derive the
explicit forms of the states of the atom and the modes at these values of the interaction times. 相似文献
2.
S. Abdel-Khalek 《Physica A》2008,387(4):779-786
We study the interaction between a moving two-level atom and a single-mode field. The coupled atom-cavity system with atomic center-of-mass motion included is modeled by considering the dependence of the atomic motion along z-axis. At exact resonance between the internal atomic transition and the cavity eigenfrequency, an exact solution of the system is obtained and periodically modulated Rabi oscillations and regular translational motion are observed. We focused on the dynamics of both field Wehrl entropy and Wehrl phase distribution. The influence of the atomic motion on the evolution of von Neumann entropy and Wehrl entropy is examined. The results show that the atomic motion and the field-mode structure play important roles in the evolution of the von Neumann entropy, Wehrl entropy and Wehrl PD. 相似文献
3.
We study the dynamics of the von Neumann entropy, Wehrl entropy, and Wehrl phase distribution for a single four-level ladder-type atom interacting with a one-mode cavity field taking into account the atomic motion. We obtain the exact solution of the model using the Schr¨odinger equation under specific initial conditions. Also we investigate the quantum and classical quantifiers of this system in the nonresonant case. We examine the effects of detuning and the atomic motion parameter on the entropies and their density operators. We observe an interesting monotonic relation between the different physical quantities in the case of nonmoving and moving atoms during the time evolution. We show that both the detuning and the atomic motion play important roles in the evolution of the Wehrl entropy, its marginal distributions, entanglement, and atomic populations. 相似文献
4.
We study the interaction of a V-type three-level atom with a two-mode field through the two-photon interaction when the atom is initially in the upper state
and the initial field is in the two-mode squeezed vacuum state. The influence of the atomic motion on the evolution of the
atomic Q-function and atomic Wehrl entropy is examined. The results show that the atomic motion and the mode structure play important
roles in the evolution of the atomic Q-function, atomic Wehrl entropy, and marginal atomic Wehrl entropy. 相似文献
5.
S. Abdel-Khalek Nour Zidan M. Abdel-Aty 《Physica E: Low-dimensional Systems and Nanostructures》2011,44(1):6-11
We analyze different entanglement measures for a mixed state two-level system in the presence of intrinsic decoherence. The information about entanglement is obtained by comparing the results for the atomic Wehrl entropy and negativity with the analytical results for a simple case. For the strong decoherence case we find that a similar and long-lived maximum Wehrl entropy and negativity between atom and field are shown. The results highlight the important roles played by both the decoherence parameter and the initial state setting in determining the evolution of the atomic Wehrl entropy and negativity. 相似文献
6.
7.
A.-S.F. Obada 《Physica A》2010,389(4):891-898
In this paper, the concept of atomic Fisher information (AFI) is introduced. The marginal distributions of the AFI are defined. This quantity is used as a parameter of entanglement and compared with linear and atomic Wehrl entropies of the two-level atom. The evolution of the atomic Fisher information and atomic Wehrl entropy for only the pure state (or dissipation-free) of the Jaynes-Cummings model is analyzed. We demonstrate the connections between these measures. 相似文献
8.
S. Abdel-Khalek 《Journal of Russian Laser Research》2011,32(1):86-93
We study the entanglement between a single five-level atom interacting with a one-mode cavity field in the case where the atomic motion is taken into account. The field entropy of this system is investigated under the nonresonant conditions. The effects of the detuning parameter and the atomic motion on the degree of entanglement are investigated. We show that both the detuning and atomic motion play important roles in the evolution of the von Neumann entropy and atomic populations. 相似文献
9.
In this paper we are interested in studying the entanglement between a single four-level ladder-type atom interacting with
one-mode cavity field when the atomic motion is taken into account. The exact solution of the model is obtained by using Schrodinger
equation for a specific initial conditions. The field entropy of this system is investigated in the non-resonant case. The
effects of the detuning parameter and the atomic motion on the entanglement degree are examined. These investigations show
that both of the detuning and the atomic motion play important roles in the evolution of the von Neumann entropy and atomic
populations. Finally, conclusions and some features are given. 相似文献
10.
The time evolution of the field quantum entropy and entanglement in a system of multi-mode coherent light field resonantly
interacting with a two-level atom by degenerating the multi-photon process is studied by utilizing the Von Neumann reduced
entropy theory, and the analytical expressions of the quantum entropy of the multimode field and the numerical calculation
results for three-mode field interacting with the atom are obtained. Our attention focuses on the discussion of the influences
of the initial average photon number, the atomic distribution angle and the phase angle of the atom dipole on the evolution
of the quantum field entropy and entanglement. The results obtained from the numerical calculation indicate that: the stronger
the quantum field is, the weaker the entanglement between the quantum field and the atom will be, and when the field is strong
enough, the two subsystems may be in a disentangled state all the time; the quantum field entropy is strongly dependent on
the atomic distribution angle, namely, the quantum field and the two-level atom are always in the entangled state, and are
nearly stable at maximum entanglement after a short time of vibration; the larger the atomic distribution angle is, the shorter
the time for the field quantum entropy to evolve its maximum value is; the phase angles of the atom dipole almost have no
influences on the entanglement between the quantum field and the two-level atom. Entangled states or pure states based on
these properties of the field quantum entropy can be prepared. 相似文献
11.
Jing Zhang 《Optics Communications》2007,277(2):353-358
As an important parameter, von Neumann entropy has been used to characterize the entanglement between atom and light field. We discussed the entanglement and nonclassicality evolution of an atom in a squeezed vacuum—a typical nonclassical field, and compare it with that of the coherent state. It shows that the atom-field entanglement in squeezed vacuum is much stronger and stabler than that in coherent state, whereas the nonclassicality of the light field depends on its initial status. This investigation is trying to find a new insight into the relation between entanglement of atom-field system and nonclassicality of light fields. The result shows that the entanglement between the atom and the field can be maintained well in the squeezed vacuum and this implies better control of atom and photon mutually. 相似文献
12.
Single-atom entropy squeezing for two two-level atoms interacting with a single-mode radiation field
In this paper we consider a system of two two-level atoms interacting with a single-mode quantized electromagnetic field in a lossless resonant cavity via l-photon-transition mechanism. The field and the atoms are initially prepared in the coherent state and the excited atomic states, respectively. For this system we investigate the entropy squeezing, the atomic variances, the von Neumann entropy and the atomic inversions for the single-atom case. Also we comment on the relationship between spin squeezing and linear entropy. We show that the amounts of the nonclassical effects exhibited in the entropy squeezing for the present system are less than those produced by the standard Jaynes-Cummings model. The entropy squeezing can give information on the corresponding von Neumann entropy. Also the nonclassical effects obtained from the asymmetric atoms are greater than those obtained from the symmetric ones. Finally, the entropy squeezing gives better information than the atomic variances only for the asymmetric atoms. 相似文献
13.
Giacomo De Palma 《Letters in Mathematical Physics》2018,108(9):2139-2152
We prove two new fundamental uncertainty relations with quantum memory for the Wehrl entropy. The first relation applies to the bipartite memory scenario. It determines the minimum conditional Wehrl entropy among all the quantum states with a given conditional von Neumann entropy and proves that this minimum is asymptotically achieved by a suitable sequence of quantum Gaussian states. The second relation applies to the tripartite memory scenario. It determines the minimum of the sum of the Wehrl entropy of a quantum state conditioned on the first memory quantum system with the Wehrl entropy of the same state conditioned on the second memory quantum system and proves that also this minimum is asymptotically achieved by a suitable sequence of quantum Gaussian states. The Wehrl entropy of a quantum state is the Shannon differential entropy of the outcome of a heterodyne measurement performed on the state. The heterodyne measurement is one of the main measurements in quantum optics and lies at the basis of one of the most promising protocols for quantum key distribution. These fundamental entropic uncertainty relations will be a valuable tool in quantum information and will, for example, find application in security proofs of quantum key distribution protocols in the asymptotic regime and in entanglement witnessing in quantum optics. 相似文献
14.
Rosa Safaiee Mohammad Mehdi Golshan 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(6):121
The main purpose of the present article is to report the characteristics of von Neumann entropy, thereby, the electronic hybrid entanglement, in the heterojunction of two semiconductors, with due attention to the Rashba and Dresselhaus spin-orbit interactions. To this end, we cast the von Neumann entropy in terms of spin polarization and compute its time evolution; with a vast span of applications. It is assumed that gate potentials are applied to the heterojunction, providing a two dimensional parabolic confining potential (forming an isotropic nanodot at the junction), as well as means of controlling the spin-orbit couplings. The spin degeneracy is also removed, even at electronic zero momentum, by the presence of an external magnetic field which, in turn, leads to the appearance of Landau states. We then proceed by computing the time evolution of the corresponding von Neumann entropy from a separable (spin-polarized) initial state. The von Neumann entropy, as we show, indicates that electronic hybrid entanglement does occur between spin and two-dimensional Landau levels. Our results also show that von Neumann entropy, as well as the degree of spin-orbit entanglement, periodically collapses and revives. The characteristics of such behavior; period, amplitude, etc., are shown to be determined from the controllable external agents. Moreover, it is demonstrated that the phenomenon of collapse-revivals’ in the behavior of von Neumann entropy, equivalently, electronic hybrid entanglement, is accompanied by plateaus (of great importance in quantum computation schemes) whose durations are, again, controlled by the external elements. Along these lines, we also make a comparison between effects of the two spin-orbit couplings on the entanglement (von Neumann entropy) characteristics. The finer details of the electronic hybrid entanglement, which may be easily verified through spin polarization measurements, are also accreted and discussed. The novel results of the present article, with potent applications in the field of quantum information processing, provide a deeper understanding of the electronic von Neumann entropy and hybrid entanglement that occurs in two-dimensional nanodots. 相似文献
15.
In this paper, we study the dynamics of entanglement between three-level atom and optical field, initially prepared in the squeezed coherent state. We discuss the dynamical behavior of the geometric phase and entanglement, measured by the von Neumann entropy, with and without rotating wave approximation during the time of evolution. The effect of the squeezing and detuning parameters on the evolution of entanglement and geometric phase will be examined. We find that the squeezing and detuning parameters play a central role on the evolution of the geometric phase and nonlocal correlation between the field and the three-level atom. Moreover, we show that the dynamics of the system in the presence of rotating wave approximation has a richer structure compared with the absence of rotating wave approximation. 相似文献
16.
In this paper, we consider the model which consists of a degenerate Raman process involving two degenerate Rydberg energy levels of an atom interacting with a single-mode cavity field. The influence of the atomic coherence on the von Neumann entropy of the atom and the atomic inversion is investigated. It is shown that the atomic coherence decreases the amount of atom-field entanglement. It is also found that the collapse and revival times are independent of the atomic coherence, while the amplitude of the revivals is sensitive to this coherence. Moreover, the Q function and the entropy squeezing of the field are examined. Some new conclusions can be obtained. 相似文献
17.
应用Von Neumann熵和Schmid tnumber K两种纠缠度量讨论了各向异性光子晶体中二能级原子和自发辐射场间纠缠度的演化性质.研究发现,原子-光场纠缠度的演化与原子上能级和光子晶体能带带边的相对位置有关,当原子上能级处于光子晶体禁带内,原子-光场纠缠度将保持稳定,当原子上能级处于光子晶体能带中,原子-光场纠缠度先增大后衰减到零.纠缠度的大小还与原子的初态有关.可以通过控制原子的初态和原子上能级与带边的相对位置来控制原子-光场纠缠度的演化特性. 相似文献
18.
考虑一个运动的二能级原子与单模热光场经由多光子过程相互作用, 利用量子约化熵理论研究原子与场之间的熵交换、用Concurrence量度原子与场之间的纠缠, 讨论原子初态、原子运动、热场平均光子数以及跃迁光子数对熵交换和纠缠的影响. 结果表明: 考虑原子运动时, 原子和光场熵变呈现周期性, 且发生熵交换现象; 与热光场的相互作用导致运动原子与场纠缠, 多光子过程有利于纠缠加强. 在原子和光场熵变均为零处, 纠缠也为零. 相似文献
19.
In this paper, we derive the time dependent solution of the effective master equation for the reduced density matrix operator of a two-level atom driven by a strong classical field and damped into a “modelled” reservoir with non-flat density of modes. The effects of different parameters on the atomic inversion, the von Neumann entropy and the entropy squeezing are discussed. 相似文献