Study on quantum thermalization from thermal initial states in a superconducting quantum computer.

Quantum thermalization in contemporary quantum devices, in particular quantum computers, has recently attracted significant interest. However, there are few experimental results due to the difficulty in preparing thermal states in quantum systems. In this paper, we propose a protocol to indirectly address this challenge using only pure states. While our protocol does not solve the issue of thermal state preparation, it enables the equivalent study of their dynamics. Moreover, we experimentally validate our protocol using IBM quantum devices, presenting results that demonstrate unusual relaxation in equidistant quenches. We also assess the formalism introduced for the Quantum Mpemba Effect (QME), which provides a framework for comparing the dynamics of different thermal states, we do no observe any unusual behaviour in this case, which is consistent with the theoretical predictions for the system. This demonstration underscores that our protocol can provide an alternative way of studying thermal states physics when their direct preparation may be too difficult.