One formidable difficulty in quantum communication and computation is to protect information-carrying quantum states against undesired interactions with the environment. To address this difficulty, many good quantum error-correcting codes have been derived as binary stabilizer codes. Fault-tolerant quantum computation prompted the study of nonbinary quantum codes, but the theory of such codes is not as advanced as that of binary quantum codes. This paper describes the basic theory of stabilizer codes over finite fields. The relation between stabilizer codes and general quantum codes is clarified by introducing a Galois theory for these objects. A characterization of nonbinary stabilizer codes over Fq in terms of classical codes over Fq 2 is provided that generalizes the well-known notion of additive codes over F4 of the binary case. This paper also derives lower and upper bounds on the minimum distance of stabilizer codes, gives several code constructions, and derives numerous families of stabilizer codes, including quantum Hamming codes, quadratic residue codes, quantum Melas codes, quantum Bose-Chaudhuri-Hocquenghem (BCH) codes, and quantum character codes. The puncturing theory by Rains is generalized to additive codes that are not necessarily pure. Bounds on the maximal length of maximum distance separable stabilizer codes are given. A discussion of open problems concludes this paper

Nonbinary Stabilizer Codes Over Finite Fields

In order to protect copyrighted material, codes may be embedded in the content or codes may be associated with the keys used to recover the content. Codes can offer protection by providing some form of traceability (TA) for pirated data. Several researchers have studied different notions of TA and related concepts in previous years. "Strong" versions of TA allow at least one member of a coalition that constructs a "pirate decoder" to be traced. Weaker versions of this concept ensure that no coalition can "frame" a disjoint user or group of users. All these concepts can be formulated as codes having certain combinatorial properties. We study the relationships between the various notions, and we discuss equivalent formulations using structures such as perfect hash families. We use methods from combinatorics and coding theory to provide bounds (necessary conditions) and constructions (sufficient conditions) for the objects of interest.

Combinatorial properties of frameproof and traceability codes

One formidable difficulty in quantum communication and computation is to protect information-carrying quantum states against undesired interactions with the environment. In past years, many good quantum error-correcting codes had been derived as binary stabilizer codes. Fault-tolerant quantum computation prompted the study of nonbinary quantum codes, but the theory of such codes is not as advanced as that of binary quantum codes. This paper describes the basic theory of stabilizer codes over finite fields. The relation between stabilizer codes and general quantum codes is clarified by introducing a Galois theory for these objects. A characterization of nonbinary stabilizer codes over GF(q) in terms of classical codes over GF(q^2) is provided that generalizes the well-known notion of additive codes over GF(4) of the binary case. This paper derives lower and upper bounds on the minimum distance of stabilizer codes, gives several code constructions, and derives numerous families of stabilizer codes, including quantum Hamming codes, quadratic residue codes, quantum Melas codes, quantum BCH codes, and quantum character codes. The puncturing theory by Rains is generalized to additive codes that are not necessarily pure. Bounds on the maximal length of maximum distance separable stabilizer codes are given. A discussion of open problems concludes this paper.

https://arxiv.org/pdf/quant-ph/0508070.pdf

Nonbinary stabilizer codes over finite fields

We consider a general fingerprinting problem of digital data under which coalitions of users can alter or erase some bits in their copies in order to create an illegal copy. Each user is assigned a fingerprint which is a word in a fingerprinting code of size M (the total number of users) and length n. We present binary fingerprinting codes secure against size-t coalitions which enable the distributor (decoder) to recover at least one of the users from the coalition with probability of error exp(-/spl Omega/(n)) for M=exp(/spl Omega/(n)). This is an improvement over the best known schemes that provide the error probability no better than exp(-/spl Omega/(n/sup 1/2/)) and for this probability support at most exp(O(n/sup 1/2/)) users. The construction complexity of codes is polynomial in n. We also present versions of these constructions that afford identification algorithms of complexity poly(n)=polylog(M), improving over the best previously known complexity of /spl Omega/(M). For the case t=2, we construct codes of exponential size with even stronger performance, namely, for which the distributor can either recover both users from the coalition with probability 1-exp(/spl Omega/(n)), or identify one traitor with probability 1.

/pdf/digital-fingerprinting-codes-problem-statements-371zz9ddwr.pdf

Digital fingerprinting codes: problem statements, constructions, identification of traitors

One central theme in quantum error-correction is to construct quantum codes that have a large minimum distance. Quantum maximal distance separable (MDS) codes are optimal in the sense they attain maximal minimum distance. Recently, constructing quantum MDS codes has received much attention and seems to become more and more difficult. In this paper, based on classical constacyclic codes, we construct some new quantum MDS codes by employing the Hermitian construction. Compared with the known quantum MDS codes, these quantum MDS codes have much larger minimum distance.

Constacyclic Codes and Some New Quantum MDS Codes

Let C be a code of length n over an alphabet of q letters. An n-word y is called a descendant of a set of t codewords x1, . . . ,xt if $y_i\in\{x^1_i,\dots,x^t_i\}$ for all i=1, . . . ,n. A code is said to have the t-identifying parent property if for any n-word that is a descendant of at most t parents it is possible to identify at least one of them. We prove that for any $t\le q-1$ there exist sequences of such codes with asymptotically nonvanishing rate.

/pdf/a-hypergraph-approach-to-the-identifying-parent-property-the-4ajof6xrj9.pdf

A Hypergraph Approach to the Identifying Parent Property: The Case of Multiple Parents

Recently, Steane (1998) proposed an enlargement of the Calderbank-Shor-Steane construction. Here we further improve on the parameters obtained from his construction, present examples of new codes, and analyze asymptotical non-constructive bounds.

On binary constructions of quantum codes

Using the notion of generalized weight we improve estimates on the parameters of quantum codes obtained by Steane's construction from binary codes. This yields several new families of quantum codes.

https://arxiv.org/pdf/quant-ph/9812065.pdf

Sylvia B. Encheva

Papers

A Hypergraph Approach to the Identifying Parent Property: The Case of Multiple Parents

On binary constructions of quantum codes

On binary constructions of quantum codes

A hypergraph approach to the identifying parent property: the case of multiple parents

Intersecting codes and separating codes