Capacity of Quantum Private Information Retrieval With Multiple Servers

We study the capacity of quantum private information retrieval (QPIR) with multiple servers. In QPIR problem servers, a user retrieves classical file by downloading systems from servers each which contains copy set while identity downloaded is not leaked to server. The defined as maximum rate size over whole dimension systems. When are assumed share prior entanglement, we prove that 1 regardless number and files. construct rate-one protocol only two This capacity-achieving outperforms its counterpart in sense capacity, server secrecy, upload cost. strong converse bound derived concisely without using any secrecy condition. also multi-round 1.