Critical conditions protecting entanglement
Quantum Research Group, School of Chemistry and
Physics, University of KwaZulu-Natal and National Institute for Theoretical Physics
(NITheP), KwaZulu-Natal, Durban
Published online: 19 August 2013
The long time dynamics of two qubits, coupled to a common reservoir, and the entanglement can be controlled uniquely by manipulating the spectral density near a band gap and via the initial configuration. The spectral density may be arbitrarily shaped at high frequencies. For transition frequencies larger than the band gap, critical configurations give arbitrarily slow relaxations to the asymptotic regimes. In the non-critical configurations and in the critical configurations of the sub-ohmic condition, the concurrence tends to the same stable value, reaching unity in the singlet state, showing persistence of entanglement. In the critical configurations of the super-ohmic regime, the concurrence oscillates and special conditions make the maxima reach unity and minima vanish at estimated times, showing recursion of events of sudden death and revival of entanglement.
Key words: Quantum Information
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013