Paweł Mazurek, Katarzyna Roszak, Ravindra W. Chhajlany, Paweł Horodecki
We study the decay of entanglement of quantum dot electron-spin qubits under hyperfine interaction mediated decoherence. We show that the system displays two qualitatively different behaviors in the low and high magnetic field limits. At high magnetic fields, an initial Bell state will undergo exponential entanglement decay, where the amount of entanglement left in the system is proportional to the non-zero coherence. Contrarily, at low magnetic fields sudden-death-type behavior is observed and disentanglement is faster than the decay of coherence. Furthermore, we have found that the time of complete disentanglement displays a counter-intuitive, non-monotonic dependence on the magnetic field.
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http://arxiv.org/abs/1304.1749
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