It is often assumed that the ancilla qubits required for encoding a qubit in quantum error correction (QEC) have to be in pure states, ∣00...0> for example. In this letter, we seek an encoding scheme, in which the ancillae may be in a uniformly mixed state. We demonstrate our scheme experimentally by making use of a three-qubit NMR quantum computer. Moreover, the encoded state has an interesting nature in terms of Quantum Discord, or purely quantum correlations between the data-qubit and ancillae.
@article{arxiv.1209.0557,
title = {Quantum Error Correction with Uniformly Mixed State Ancillae},
author = {Yasushi Kondo and Chiara Bagnasco and Mikio Nakahara},
journal= {arXiv preprint arXiv:1209.0557},
year = {2013}
}