Controlling Entanglement Sudden Death and Revival in Two Interacting Asymmetric Qubits Coupled off-Resonance to a Radiation Field

The recent great interest in realizing quantum information processing (QIP) systems led to newly engineered quantum systems such as the semiconducting quantum dots and superconducting qubits, and customized natural systems such as trapped ions and Rydberg atoms, which enjoy a strong coupling with a similar type or a different one in hybrid structures. These qubits were integrated successfully into cavity (circuit) QED systems to perform different QIP schemes. In previous works, we studied the entanglement sudden death (ESD) in a system of two identical interacting qubits coupled off-resonance to a radiation field [1,2]. In this work, we extended our model to study the case of two interacting non-identical qubits coupled off-resonance to a radiation field. This model accounts for qubits of the same type or two different types in a hybrid structure. We provide an exact analytical solution for the cumbersome problem of the system dynamics starting from any initial state. The extent to which the asymmetry can affect the behavior of ESD and entanglement sudden birth (ESB) is illustrated through considering different initially entangled (disentangled) states at various average detunings, average atom-field interaction strengths, and mean number of photons. The famous death-revival patterns are observed, and the two qubits system is found to converge to pseudo-steady states that can be reached in shorter periods of time as the average interaction strength is increased. The pseudo-steady states were shown to exhibit a more systematic behavior relative to early-stage entanglement dynamics. A quantitative approach to describe the entanglement in the pseudo-steady states was provided through defining pseudo-steady intensities. Interestingly, among all the investigated states, the initial singlet Bell state demonstrated the most systematic behavior of global optimization of asymptotic entanglement with high sensitivity to the asymmetry effects. In contrast, the other entangled and disentangled states exhibited scattered random asymptotic entanglement maxima with no systematic pattern.

[1] Gehad Sadiek, Wiam Al-Drees and Sebawe Abdullah, Optics Express 27, 33799 (2019).

[2] Gehad Sadiek, Wiam Al-Drees, Salwa Shaglel and Hala Elhag, Entropy 23, 00629 (2021).