Parallel remote state preparation for fully device-independent verifiable blind quantum computation

We introduce a device-independent two-prover scheme in which a classical verifier can use a simple untrusted quantum measurement device (the client device) to securely delegate a quantum computation to an untrusted quantum server. To do this, we construct a parallel self-testing protocol to perform device-independent remote state preparation of $n$ qubits and compose this with the unconditionally secure universal verifiable blind quantum computation (VBQC) scheme of Fitzsimons and Kashefi [Phys. Rev. A 96, 012303 (2017)]. Our self-test achieves a multitude of desirable properties for the application we consider, giving rise to practical and fully device-independent VBQC. It certifies parallel measurements of all cardinal and intercardinal directions in the $XY$ plane as well as the computational basis, uses few input questions (of size logarithmic in $n$ for the client and a constant number communicated to the server), and requires only single-qubit measurements to be performed by the client device.