Title: Ferroelectric modulation of quantum emitters in monolayer WS$_2$

Abstract: Quantum photonics promises significant advances in secure communications, metrology, sensing and information processing/computation. Single photon sources are fundamental to this endeavor. However, the lack of high quality single photon sources remains a significant obstacle. We present here a new paradigm for the control of single photon emitters (SPEs) and single photon purity by integrating monolayer WS$_2$ with the organic ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)). We demonstrate that the ferroelectric domains in the P(VDF-TrFE) film control the purity of single photon emission from the adjacent WS$_2$. By switching the ferroelectric polarization, we reversibly tune the single photon purity between the semi-classical and quantum light regimes, with single photon purities as high as 94%. This provides another avenue for modulating and encoding quantum photonic information, complementing more complex approaches. This novel multidimensional heterostructure introduces a new avenue for control of quantum emitters by combining the nonvolatile ferroic properties of a ferroelectric with the radiative properties of the zero-dimensional atomic scale emitters embedded in the two-dimensional WS$_2$ semiconductor monolayer.