Quantum computing is currently experiencing rapid progress. Due to the complexity and continuous growth of knowledge in this field, it is essential to store information in a way that allows an easy access, analysis and navigation over reliable resources. Knowledge graphs (KGs) with machine-readable semantics offer a structural information representation and can enhance the capabilities of knowledge processing and information retrieval. In this paper, we extend the platform and ecosystem for quantum applications (PlanQK) for a KG. Specifically, we describe how the quantum computing knowledge, which is submitted on the platform by researchers and industry actors, is incorporated into the graph. Moreover, we outline the semantic search over the PlanQK KG.