As far as I know, QDrant (and most vector stores) store the entire index on the vector_store (a little hacky, but it's extremely convienant)
To re-connect to a vector store you created on QDrant, you should be able to do something like this (assuming you connect the client to a previously created vector store on qdrant)
vector_store = QdrantVectorStore(client=client, collection_name="paul_graham")
storage_context = StorageContext.from_defaults(vector_store=vector_store)
index = VectorStoreIndex([], storage_context=storage_context)