Communicating Over Adversarial Quantum Channels Using Quantum List Codes

In this correspondence, we study quantum communication in the presence of adversarial noise. In this setting, communicating with perfect fidelity requires a quantum code of bounded minimum distance, for which the best known rates are given by the quantum Gilbert-Varshamov (QGV) bound. Asking only for arbitrarily high fidelity and letting the sender and receiver use a secret key of length logarithmic in the number of qubits sent, we find a dramatic improvement over the QGV rates. In fact, our protocols allow high fidelity transmission at noise levels for which perfect fidelity is impossible. To achieve such rates, we introduce fully quantum list codes, which may be of independent interest.