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