Abstract
We study the generation of quantum correlations between two excitonic quantum dot qubits due to their interaction with the same phonon environment. Such generation results from the fact that during the pure dephasing process at finite temperatures, each exciton becomes entangled with the phonon environment. We find that for a wide range of temperatures quantum correlations are created due to the interaction. The temperature-dependence of the level of correlations created displays a trade-off type behaviour; for small temperatures the phonon-induced distrubance of the qubit states is too small to lead to a distinct change of the two-qubit state, hence, the level of created correlations is small, while for large temperatures the pure dephasing is not accompanied by the creation of entanglement between the qubits and the environment, so the environment cannot mediate qubit-qubit quantum correlations.
Highlights
We study the generation of quantum correlations between two excitonic quantum dot qubits due to their interaction with the same phonon environment
It has been recently shown that a weaker type of quantum correlations, those which are measured by the quantum discord[7,8,9] and which are sometimes present in separable states, are useful from the perspective of quantum computation[10,11,12,13,14,15,16,17,18,19]
The interaction leads to pure dephasing of the qubit states which is only partial due to the super-Ohmic nature of the phonon bath
Summary
We study the generation of quantum correlations between two excitonic quantum dot qubits due to their interaction with the same phonon environment Such generation results from the fact that during the pure dephasing process at finite temperatures, each exciton becomes entangled with the phonon environment. It has been recently shown that such a process is, at finite temperatures, always accompanied by the creation of entanglement between the qubit and the environment[29], and we can expect some kind of quantum correlations to be generated between qubits via the interaction with a common phonon environment. We study a system composed of two QD excitonic qubits separated by a finite distance and, interacting with a common environment of phonons We find that such an interaction will lead to the creation of finite quantum discord values between the two qubits, if the distance between them is small enough that the environments cannot be treated as separate, and the temperature is modest. We identify two most prominent features of the evolution during the generation of the quantum discord and study their origin and parameter dependence (which are both different) with the help of X-states whose quantum correlations are easier to quantify
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