Published online by Cambridge University Press: 25 January 2021
The level of distribution of a complex-valued sequence $b$ measures the quality of distribution of $b$ along sparse arithmetic progressions $nd+a$. We prove that the Thue–Morse sequence has level of distribution $1$, which is essentially best possible. More precisely, this sequence gives one of the first nontrivial examples of a sequence satisfying a Bombieri–Vinogradov-type theorem for each exponent $\theta <1$. This result improves on the level of distribution $2/3$ obtained by Müllner and the author. As an application of our method, we show that the subsequence of the Thue–Morse sequence indexed by $\lfloor n^c\rfloor$, where $1 < c < 2$, is simply normal. This result improves on the range $1 < c < 3/2$ obtained by Müllner and the author and closes the gap that appeared when Mauduit and Rivat proved (in particular) that the Thue–Morse sequence along the squares is simply normal.
The author acknowledges support by the Austrian Science Fund (FWF), Project F5502-N26, which is a part of the Special Research Program ‘Quasi Monte Carlo Methods: Theory and Applications’. The author also wishes to acknowledge support by the project MuDeRa, which is a joint project between the FWF (I-1751-N26) and the ANR (Agence Nationale de la Recherche, France, ANR-14-CE34-0009).