Time-invariant discord: high temperature limit and initial environmental correlations
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We present a thorough investigation of the phenomena of frozen and time-invariant quantum discord for two-qubit systems independently interacting with local reservoirs. Our work takes into account several significant effects present in decoherence models, which have not been yet explored in the context of time-invariant quantum discord, but which in fact must be typically considered in almost all realistic models. Firstly, we study the combined influence of dephasing, dissipation and heating reservoirs at finite temperature. Contrarily to previous claims in the literature, we show the existence of time-invariant discord at high temperature limit in the weak coupling regime and also examine the effect of thermal photons on the dynamical behavior of frozen discord. Secondly, we explore the consequences of having initial correlations between the dephasing reservoirs. We demonstrate in detail how the time-invariant discord is modified depending on the relevant system parameters such as the strength of the initial amount of entanglement between the reservoirs.
KeywordsTime-invariant discord Control of discord High temperature limit Open quantum systems
This work has been supported by the University of Kurdistan. F. T. T. thanks R. Yousefjani for the useful discussions. G. K. is grateful to Sao Paulo Research Foundation (FAPESP) for the support given under the Grant Number 2012/18558-5. S. M. also acknowledges financial support from the Academy of Finland (Project No. 287750).
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