Entanglement dynamics and population inversion of a two-qubit system in two cavities coupled with optical fiber in the presence of two-photon transition
S. A. S. Musavi, Mohammad Kazem Tavassoly, S. Salimian
In this paper, the entanglement between two qubits that exist in two distinct cavities which are connected by an optical fiber is investigated by using the concurrence, while two-photon transitions and Kerr medium effect are also considered. Each cavity contains a qubit and a single-mode quantized field. The appearance of entanglement between the two qubits in the separate cavities originates from the presence of optical fiber. The obtained numerical results of the considered system show that, if the Kerr medium is large enough, the initial values of entanglement between the two qubits (which may have the maximum possible value, i.e. 1) can be approximately protected from the large amplitude fluctuations, so that acceptable stability is created. Also, qubit-field coupling and detuning effects are investigated and it is observed that symmetric coupling results in more stability of entanglement. Eventually, atomic population inversion is also studied and it is observed that it is controllable by considering different parameters.
In this paper, the entanglement between two qubits that exist in two distinct cavities which are connected by an optical fiber is investigated by using the concurrence, while two-photon transitions and Kerr medium effect are also considered. Each cavity contains a qubit and a single-mode quantized field. The appearance of entanglement between the two qubits in the separate cavities originates from the presence of optical fiber. The obtained numerical results of the considered system show that, if the Kerr medium is large enough, the initial values of entanglement between the two qubits (which may have the maximum possible value, i.e. 1) can be approximately protected from the large amplitude fluctuations, so that acceptable stability is created. Also, qubit-field coupling and detuning effects are investigated and it is observed that symmetric coupling results in more stability of entanglement. Eventually, atomic population inversion is also studied and it is observed that it is controllable by considering different parameters.
In this paper, we explore the atomic population inversion and entanglement dynamics of a quantum system consisting of three identical two-level atoms interacting with a single-mode cavity field. The cavity is surrounded by a Kerr medium exhibiting f-deformed Kerr nonlinearity, and we consider a degenerate multi-photon transition in the nonlinear regime. The study systematically analyzes the effects of intensity-dependent coupling, detuning, Kerr nonlinearity, f-deformed Kerr nonlinearity, and multi-photon transition on the nonclassical properties of the system. Our results show that the Kerr and f-deformed Kerr nonlinearities significantly influence the atomic inversion dynamics, leading to phenomena such as collapse and revival, with distinct behaviors observed under varying detuning parameters. Furthermore, entanglement dynamics between the atoms and cavity mode are enhanced under intensity-dependent coupling and nonlinearity. The detuning parameter generally reduces entanglement but has a less pronounced effect in the two-photon transition case, where entanglement is notably enhanced. The study provides valuable insights into controlling quantum correlations in multi-atom systems, with potential applications in quantum information processing, computing, and communication.
In this study, we theoretically investigate a system composed of two isolated two-level atoms, each confined within an independent single-mode optical cavity. The cavities are coherently coupled via an optical fiber, enabling photon-mediated interaction between the two subsystems. Each cavity sustains a single-mode quantized electromagnetic field, and each atom couples exclusively to the field within its respective cavity. We analyze the time dependent entanglement dynamics, exploring both atom-atom and cavity-field bipartite entanglement under this hybrid interaction framework. To quantify entanglement, we employ concurrence as the measurement metric. The effects of the atoms' initial states and the optical fiber’s coupling strength on both atom-atom and field-field entanglement are analyzed. Numerical results reveal that when the coupling strength of the optical fiber is close to zero, no entanglement is observed between either the atoms or the fields. However, as the fiber coupling strength increases, entanglement emerges and exhibits collapse and revival behavior over time.
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.
In this research, we investigate the entanglement between two cavities, each consisting of a two-level atom and a deformed multi-photon field. The model used in this study is the deformed Jaynes-Cummings (DJC) model. A physical interpretation of the introduced model is that there are two separate cavities with Kerr-like environments, each containing a two-level atom and a non-deformed multi-photon field, where each atom interacts locally with its corresponding field. Generally, we assume that the coupling constants between the atoms and fields are unequal, and we also consider non-zero detuning. We prove that the simple rules applicable to symmetric cavities without detuning do not hold for asymmetric cavities. We will show that the presence of asymmetric cavities and detuning are factors that can be used to control entanglement. Additionally, we examine the effects of deformed fields (Kerr-like environments) on the temporal evolution of entanglement and demonstrate that they cause the entanglement to become more oscillatory. We will show that when the sign of entanglement changes, the temporal evolution of entanglement will be completely different. We consider two different initial states of the system and show that the temporal evolution of entanglement will differ for these two states. In fact, the temporal evolution of entanglement depends on the initial state of the system. To measure the entanglement, we use the concurrence parameter, where a value of one indicates maximum entanglement and a value of zero indicates no entanglement. We will also show that an initial maximum atomic entanglement can be transferred to another pair of qubits, and the type of this qubit pair depends on whether the ratios of the coupling constants are even or odd. We demonstrate that for odd ratios of coupling constants, the initial maximum atomic entanglement can be completely transferred to the fields at a specific time.
An entangled state, as an essential tool in quantum information processing, may be generated through the interaction between light and matter in cavity quantum electrodynamics. In this paper, we study the interaction between two two-level atoms and a two-mode field in an optical cavity enclosed by a medium with Kerr nonlinearity in the presence of a detuning parameter and Stark effect. It is assumed that the atom–field coupling and third-order susceptibility of the Kerr medium depend on the intensity of the light. In order to investigate the dynamics of the introduced system, we obtain the exact analytical form of the state vector of the considered atom–field system under initial conditions which may be prepared for the atoms (in a coherent superposition of their ground and upper states) and the fields (in a standard coherent state). Then, in order to evaluate the degree of entanglement between the subsystems, we investigate the dynamics of the entanglement by employing the entanglement of formation. Finally, we analyze in detail the influences of the Stark shift, the deformed Kerr medium, the intensity-dependent coupling, and also the detuning parameter on the behavior of this measure for different subsystems. The numerical results show that the amount of entanglement between the different subsystems can be controlled by choosing the evolved parameters appropriately.
We theoretically investigate optical bistability and entanglement in a hybrid nonlinear system of two coupled cavities via a single-mode waveguide. The left cavity contains an ensemble of N quantum dots (QDs) and a Kerr medium to enhance the nonlinearity as it causes to observe the bistable behaviour of the system. We study the Kerr medium, QD ensemble, and cavity coupling effect on bistability response shown by mean intracavity photons in the left cavity. In addition, we have shown entanglement between different subsystems and found that entanglement can be generated between the two coupled cavity photons, cavity photons, and QD ensembles. Additionally, we investigate the effect of different parameters on entanglement. Our findings show that Kerr nonlinearity and the hopping parameter between the two cavities can effectively control the optical properties of the proposed hybrid system, which can be used to design efficient optical devices and the entangled optical photons have applications such as quantum information transfer.