Detecting Non-Markovianity via Linear Entropy of Choi State

Non-Markovian dynamics detection is one of the most popular subjects in quantum information science. In this paper, a linear-entropy-based non-Markovianity witness scheme is constructed. The positive definiteness of the Choi state will be broken in non-Markovian evolution, which can be witnessed by its linear entropy. Thus, the linear entropy of the Choi state can be used to witness non-Markovian dynamics. The effectiveness of the proposed method is verified using the pure dephasing channel as an example. Finally, it is shown that this method can be extended to the one based on Rényi entropy.