Error Thresholds for Arbitrary Pauli Noise

Understand

The error threshold of a one-parameter family of quantum channels is defined as the largest noise level such that the quantum capacity of the channel remains positive.

• This in turn guarantees the existence of a quantum error correction code for noise modeled by that channel.
• Discretizing the single-qubit errors leads to the important family of Pauli quantum channels; curiously, multipartite entangled states can increase the threshold of these channels beyond the so-called hashing bound, an effect termed superadditivity of coherent information.
• In this work, we divide the simplex of Pauli channels into one-parameter families and compute numerical lower bounds on their error thresholds.