Bourgain's counterexample in the sequential convergence problem for the Schr\"odinger equation

We study the problem of pointwise convegence for the Schr\"odinger operator on $\mathbb R^n$ along time sequences. We show that the sharp counterexample to the sequential Schr\"odinger maximal estimate given recently by Li, Wang and Yan based in the construction by Luc\`a and Rogers can also be achieved with the construction of Bourgain, and we extend it to the fractal setting.