  Blind quantum computation is a new secure quantum computing protocol where a
client, who does not have enough quantum technologies at her disposal, can
delegate her quantum computation to a server, who has a fully-fledged quantum
computer, in such a way that the server cannot learn anything about client's
input, output, and program. If the client interacts with only a single server,
the client has to have some minimum quantum power, such as the ability of
emitting randomly rotated single-qubit states or the ability of measuring
states. If the client interacts with two servers who share Bell pairs but
cannot communicate with each other, the client can be completely classical. For
such a double-server scheme, two servers have to share clean Bell pairs, and
therefore the entanglement distillation is necessary in a realistic noisy
environment. In this paper, we show that it is possible to perform entanglement
distillation in the double-server scheme without degrading the security of the
blind quantum computing.
