Quantum Error Correction with Uniformly Mixed State Ancillae

Yasushi Kondo, Chiara Bagnasco, Mikio Nakahara

Published 2012-09-04, updated 2012-10-04Version 2

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.