Perspectives for a mixed two-qubit system with binomial quantum states

Abstract

The problem of the relationship between entanglement and two-qubit systems in which it is embedded is central to the quantum information theory. This paper suggests that the concurrence hierarchy as an entanglement measure provides an alternative view of how to think about this problem. We consider mixed states of two qubits and obtain an exact solution of the time-dependent master equation that describes the evolution of two two-level qubits (or atoms) within a perfect cavity for the case of multiphoton transition. We consider the situation for which the field may start from a binomial state. Employing this solution, the significant features of the entanglement when a second qubit is weakly coupled to the field and becomes entangled with the first qubit, is investigated. We also describe the response of the atomic system as it varies between the Rabi oscillations and the collapse-revival mode and investigate the atomic inversion and the Q-function. We identify and numerically demonstrate the region of parameters where significantly large entanglement can be obtained. Most interestingly, it is shown that features of the entanglement is influenced significantly when the multi-photon process is involved. Finally, we obtain illustrative examples of some novel aspects of this system and show how the off-resonant case can sensitize entanglement to the role of initial state setting.

Entanglement protection of classically driven qubits in a lossy cavity

“…This is the case, for instance, of schemes with weak measurements 11 , 12 or that use quantum Zeno effect 13 – 15 , quantum error correction 16 , 17 , Stark shift 18 . Among various proposed quantum systems for practical implementations, the two-level systems (qubits) have been attracted much great attention duo to their ability of implementation in laboratories 19 – 22 .…”

Entanglement Protection of Classically Driven Qubits in a Lossy Cavity

“…This is the case, for instance, of schemes with weak measurements 11,12 or that use quantum Zeno effect [13][14][15] , quantum error correction 16,17 , Stark shift 18 . Among various proposed quantum systems for practical implementations, the two-level systems (qubits) have been attracted much great attention duo to their ability of implementation in laboratories [19][20][21][22] .…”

Quantum phase properties and Wigner function of two 2-level atoms in the presence of the Stark shift for the Tavis–Cummings model

“…It provides novel information such as quantum computing [3], teleportation [4], cryptography [5], dense coding [6] and entanglement swapping [7]. The system containing two 2-level atoms in an electromagnetic field [8][9][10][11][12][13][14][15] is one of particular interest, since it can represent two qubits, the building blocks of the quantum gates that are essential to implement quantum protocols in quantum information processing.…”