Quantum uncertainty equalities and inequalities for unitary operators

We explore the uncertainty relation for unitary operators in a new way and find two uncertainty equalities for unitary operators, which are minimized by any pure states. Additionally, we derive two sets of uncertainty inequalities that unveil hierarchical structures within the realm of unitary operator uncertainty. Furthermore, we examine and compare our method for unitary uncertainty relations to other prevailing formulations. We provide explicit examples for better understanding and clarity. Results show that the hierarchical unitary uncertainty relations establish strong bounds. Moreover, we investigate the higher-dimensional limit of the unitary uncertainty equalities. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.