Xue, ShibeiZhang, JunPetersen, Ian2023-09-081063-6536http://hdl.handle.net/1885/298845Correlations of an environment are crucial for the dynamics of non-Markovian quantum systems, which may not be known in advance. In this brief, we propose a gradient algorithm for identifying the correlations in terms of the time-varying damping rate functions in a time-convolution-less master equation for spin chains. By measuring time trace observables of the system, the identification procedure can be formulated as an optimization problem. The gradient algorithm is designed based on a calculation of the derivative of an objective function with respect to the damping rate functions, whose effectiveness is shown in a comparison with a differential approach for a two-qubit spin chain.This work was supported in part by the National Natural Science Foundation of China under Grant 61873162, in part by the Shanghai Pujiang Program under Grant 18PJ1405500, in part by the Australian Research Council Discovery Projects and Laureate Fellowships Funding Schemes under Project DP140101779, Project DP180101805, and Project FL110100020, and in part by the Air Force Office of Scientific Research under Agreement FA2386-16-1-4065. The work of J. Zhang was supported in part by the National Natural Science Foundation of China under Grant 61673264 and Grant 61533012 and in part by the State Key Laboratory of Precision Spectroscopy, East China Normal University, Chinaapplication/pdfen-AU© 2018 IEEE201910.1109/TCST.2018.28790422022-07-24