Paper detail

Cyclicity of interaction frame transformations

We identify a cyclic property of rotation sequences involving piecewise displacements $β$ about arbitrary axes in three dimensions. Specifically, when transformation to the toggling frame is applied successively $m$ times, for $β=2π/m$ the original sequence returns. This main result unites several families of rotation sequences used for error-tuned control across quantum technologies, from NMR and MRI to atomic clocks and atom-scale computing. For the widest class of cycle, $m=2$, we highlight sequence duality where every narrowband $π$-element sequence has a broadband $π$-element counterpart, and vice-versa. Higher cycles ($m>2$) connect to polyhedral models for error-tolerant sequence design, characterized by vertex axes with $m$-fold rotational symmetry. We derive original sequences and outline their applications to spin control and spin decoupling.