Quantum Fisher Information and Entanglement of Moving Two Two-Level Atoms under the Influence of Environmental Effects

Abstract

We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) of a two moving two-level atomic systems interacting with a coherent and thermal field in the presence of intrinsic decoherence (ID) and Kerr (non-linear medium) and Stark effects. The state of the entire system interacting with coherent and thermal fields is evaluated numerically under the influence of ID and Kerr (nonlinear) and Stark effects. QFI and von Neumann entropy (VNE) decrease in the presence of ID when the atomic motion is neglected. QFI and QE show an opposite response during its time evolution in the presence of a thermal environment. QFI is found to be more susceptible to ID as compared to QE in the presence of a thermal environment. The decay of QE is further damped at greater time-scales, which confirms the fact that ID heavily influences the system's dynamics in a thermal environment. However, a periodic behavior of entanglement is observed due to atomic motion, which becomes modest under environmental effects. It is found that a non-linear Kerr medium has a prominent effect on the VNE but not on the QFI. Furthermore, it has been observed that QFI and QE decay soon under the influence of the Stark effect in the absence of atomic motion. The periodic response of QFI and VNE is observed for both the non-linear Kerr medium and the Stark effect in the presence of atomic motion. It is observed that the Stark, Kerr, ID, and thermal environment have significant effects during the time evolution of the quantum system. Entanglement's sudden death" (ESD) and entanglement sudden birth" (ESB) are observed as a result of entanglement measure in some fascinating and striking physical phenomena [16][17][18][19][20]. The QE is generated in the un-entangled qubits after a finite evolution time in the case of sudden birth. The coherent field is an electromagnetic field (EM) that is considered to be more classical than its quantum field [21]. Squeezed, coherent (even and odd) states of the EM field do not have minimum uncertainty, and they are non-classical quantum states and have a large number of applications for quantum communications and in the detection of weak signals [22].Recently, properties of the Tavis-Cummings model (TCM) were investigated when the time-dependent interaction with field was observed. Open and closed quantum systems were studied in the case of QE between two atoms (qubits) [23,24]. Moreover, a three-photon process was discussed in the case of the QE of two moving atoms interacting with a single-mode field [25]. In [26], the authors studied the atomic Wehrl entropy (AWE) of a V-type three-level atomic system interacting with a two-mode squeezed vacuum state, and the results showed that atomic motion and mode structure play significant and prominent roles in the evolution of AWE.There is always a possibility that the real physical system naturally interacts with the surrounding environment. Decoherence or dissipation may be generated due to the interaction of the quantum system wi...