Power of Quantum Computation with Few Clean Qubits

@inproceedings{Fujii2016PowerOQ,
  title={Power of Quantum Computation with Few Clean Qubits},
  author={Keisuke Fujii and Hirotada Kobayashi and Tomoyuki Morimae and Harumichi Nishimura and Shuhei Tamate and Seiichiro Tani},
  booktitle={International Colloquium on Automata, Languages and Programming},
  year={2016}
}
This paper investigates the power of polynomial-time quantum computation in which only a very limited number of qubits are initially clean in the |0> state, and all the remaining qubits are initially in the totally mixed state. No initializations of qubits are allowed during the computation, nor intermediate measurements. The main results of this paper are unexpectedly strong error-reducible properties of such quantum computations. It is proved that any problem solvable by a polynomial-time… 

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