A nonadditive quantum code

Abstract

Up to now every good quantum error-correcting code discovered has had the structure of an eigenspace of an Abelian group generated by tensor products of Pauli matrices; such codes are known as stabilizer or additive codes. In this letter we present the first example of a code that is better than any code of this type. It encodes six states in five qubits and can correct the erasure of any single qubit.

2 pages, RevTeX. More information is available at http://www.research.att.com/~njas/doc/quant.html . Updated version includes an expanded introduction, and a more detailed discussion of the structure of the code