Highly-mixed measurement-based quantum computing and the one clean qubit model

Abstract

We show that a highly-mixed state in terms of a large min-entropy is useless as a resource state for measurement-based quantum computation in the sense that if a classically efficiently verifiable problem is efficiently solved with such a highly-mixed measurement-based quantum computation then such a problem can also be classically efficiently solved. We derive a similar result also for the DQC1$_k$ model, which is a generalized version of the DQC1 model where $k$ output qubits are measured. We also show that the measurement-based quantum computing on a highly-mixed resource state in terms of the von Neumann entropy, and DQC1$_k$ model are useless in another sense that the mutual information between the computation results and inputs is very small.