  Integrated quantum photonic circuits (IQPCs) with deterministically
integrated quantum emitters are critical elements for scalable quantum
information applications and have attracted significant attention in recent
years. However, scaling up them towards fully functional photonic circuits with
multiple deterministically integrated quantum emitters to generate photonic
input states remains a great challenge. In this work, we report on a monolithic
prototype IQPC consisting of two pre-selected quantum dots deterministically
integrated into nanobeam cavities at the input ports of a 2x2 multimode
interference beam-splitter. The on-chip beam splitter exhibits a splitting
ratio of nearly 50/50 and the integrated quantum emitters have high
single-photon purity, enabling on-chip HBT experiments, depicting deterministic
scalability. Overall, this marks a cornerstone toward scalable and
fully-functional IQPCs.
