Probing entanglement Entropy of quench dynamics on NISQ computers

The general purpose quantum computers serve as quantum simulators for studying complex features of quantum systems. One of the key features is the entanglement of quantum states. We simulate the quench dynamics of the Su–Schrieffer–Heeger (alternating-bond) XX model on IBMQ computers and analyze the evolution of the second-order Renyi entropy.  The time evolution operator is approximated by the Trotter-Suzuki decomposition with adaptive time-steps and the second-order Renyi entropy is measured with the randomized protocol.  The results obtained on IBMQ show that the periodicity of the entropy agrees with theory. However,  the amplitude is smaller than the theoretical value and shows an overall offset. The possible source of error could be attributed to the unwanted qubit interactions.