1. The document describes the development of a new single-cell RNA-seq method called Quartz-Seq that has higher reproducibility and sensitivity than existing methods. 2. Quartz-Seq can quantitatively detect various types of non-genetic cellular heterogeneity and can distinguish different cell types and cell cycle phases of a single cell type. 3. It can also comprehensively reveal gene expression heterogeneity between single cells of the same cell type in the same cell cycle phase.