Scalability of parametric down-conversion for generating higher-order Fock states
Johannes Tiedau, Tim J. Bartley, Georg Harder, Adriana E. Lita, Sae Woo Nam, Thomas Gerrits, Christine Silberhorn · Physical Review A · 2019
Spontaneous parametric down-conversion (SPDC) is the most widely used method to generate higher-order Fock states ($n\ensuremath{\ge}2$). Yet, a consistent performance analysis from fundamental principles is missing. Here, we address this problem by introducing a framework for state fidelity and generation probability under the consideration of losses and multimode emission. With this analysis we show the fundamental limitations of this process as well as a trade-off between state fidelity and generation rate intrinsic to the probabilistic nature of the process. This identifies the parameter space for which SPDC is useful when generating higher-order Fock states for quantum applications. We experimentally investigate the multiphoton regime of SPDC and demonstrate heralded Fock states up to $|n\ensuremath{\rangle}=4$.