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Physica Scripta

Entanglement dynamics of two electron-spin qubits in a strongly detuned and dissipative quantum-dot-cavity system

Shao-Hua Xiang, Xiao-Peng Deng, Kehui Song, Wei Wen, Zhengang Shi

Published Nov 29, 2011• 4 citations
Publisher

Abstract

We investigate the entanglement dynamics of two electron-spin qubits in the quantum-dot (QD)–microcavity system in the large-detuning limit and subjected to two different noise sources: electron-spin dephasing and relaxation. We show that when one of the two dots is prepared initially in the excited state, the created entanglement exhibits oscillatory behavior at the beginning of evolution and then completely disappears over time. For two QDs that are initially in either the Einstein–Podolsky–Rosen-Bell states or the Werner states, their entanglement evolution exhibits the same behavior in the presence of pure dephasing, but is completely different under the relaxation process. We also show that the interdot interaction induced by a single-mode cavity field does not contribute to the dynamics of entanglement for these Bell states and Werner states.

DOI
10.1088/0031-8949/84/06/065010

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We investigate entanglement of two coupled electron spins in quantum dots (QDs) in the presence of an inhomogeneous magnetic field. The important effects of the inhomogeneous field are discussed for the dynamics of entanglement. Due to the system’s symmetry, the inhomogeneity of the field is shown not to affect the evolution of entanglement for Φ-type Bell state while it plays a key role for Ψ-type Bell state. For the maximal entangled Bell states, the field is positive for the entanglement dynamics. The mean field can increase the entanglement revival for Φ-type Bell state while an inhomogeneous field can promote the entanglement revival for Ψ-type Bell state. For the unentangled initial states, the field is destructive for the entanglement generation induced by the coupling of the two spins.
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