  Mixed state quantum computation can perform certain tasks which are believed
to be efficiently intractable on a classical computer. For a specific model of
mixed state quantum computation, namely, {\it deterministic quantum computation
with a single qubit} (DQC1), recent investigations suggest that quantum
correlations other than entanglement might be responsible for the power of DQC1
model. However, strictly speaking, the role of entanglement in this model of
computation was not entirely clear. We provide conclusive evidence that there
are instances where quantum entanglement is not present in any part of this
model, nevertheless we have advantage over classical computation. This
establishes the fact that quantum dissonance (quantum correlations) present in
fully separable states provide power to DQC1 model.

Quantum Physics