Theory of Computing ------------------- Title : A Stochastic Calculus Approach to the Oracle Separation of $\mathsf{BQP}$ and $\mathsf{PH}$ Authors : Xinyu Wu Volume : 18 Number : 17 Pages : 1-11 URL : https://theoryofcomputing.org/articles/v018a017 Abstract -------- Recently, Ran Raz and Avishay Tal proved that in some relativized world, $\mathsf{BQP}$ is not contained in the polynomial-time hierarchy (STOC'19). It has been suggested that some aspects of the proof may be simplified by stochastic calculus. In this note, we describe such a simplification.