Instituto de Ciencia de Materiales de Madrid
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Limitation of entanglement due to spatial qubit separation

Roland Doll, Martijn Wubs, Peter Hänggi, and Sigmund Kohler
Europhys. Lett. 76, 547 (2006)

We consider spatially separated qubits coupled to a thermal bosonic field that causes pure dephasing. Our focus is on the entanglement of two Bell states which for vanishing separation are known as robust and fragile entangled states. The reduced two-qubit dynamics is solved exactly and explicitly. Our results allow us to gain information about the robustness of two-qubit decoherence-free subspaces with respect to physical parameters such as temperature, qubit-bath coupling strength and spatial separation of the qubits. Moreover, we clarify the relation between single-qubit coherence and two-qubit entanglement and identify parameter regimes in which the terms robust and fragile are no longer appropriate.

[ICMM-CSIC] [Condensed Matter Theory]
last modified: 15.3.2024 by Sigmund Kohler