We generalize the construction of quantum error-correcting codes from GF(4)-linear codes by Calderbank et al. to p^m-state systems. Then we show how to determine the error from a syndrome. Finally we discuss a systematic construction of quantum codes with efficient decoding algorithms.
Quantum error-correcting codes have attracted much attention. Among many research articles, the most general and systematic construction is the so called stabilizer code construction [6] or additive code construction [2], which constructs a quantum error-correcting code as an eigenspace of an Abelian subgroup S of the error group. Thereafter Calderbank et al. [3] proposed a construction of S from an additive code over the finite field F4 with 4 elements. These constructions work for tensor products of 2-state quantum systems. However Knill [8], [9] and Rains [13] observed that the construction [2], [6] can be generalized to n-state systems by an appropriate choice of the error basis. Rains [13] also generalized the construction [3] using additive codes over F4 to p-state quantum systems, but his generalization does not relate the problem of quantum code construction to classical error-correcting codes. We propose a construction of quantum error-correcting codes for p-state systems from classical error-correcting codes which is a generalization of [3]. Throughout this paper, p denotes a prime number andm a positive integer. This paper is organized as follows. In Sect. 2, we review the construction of quantum codes for nonbinary systems. In Sect. 3, we propose a construction of quantum codes for p-state systems from classical codes over Fp2 . In Sect. 4, we propose a construction of quantum codes for p-state systems from classical linear codes over Fp2m . In Sect. 5, we discuss a
Abstract : We consider quantum error-correcting codes over alphabets of arbitrary size. We generalize quantum stabilizer codes and develop Calderbank-Shor-Steane construction over quantum systems of arbitrary dimensions using the group structure of alphabets. We also develop a methodology systematically conjoining error-correcting codes into a new class of error-correcting codes. With the help of these methods we give several ways to construct quantum maximum distance separable (MDS) codes and present many families of quantum MDS codes.
Quantum computers would prove a ground-breaking effect in several re- search fields to the advantage of our society due to their proved capacity for solving some problems deemed as too complex for classical comput- ers. Consequently, there is a generalized academic effort for constructing a quantum computer. Nonetheless, a real quantum computer does not suffice for implementing quantum algorithms reliably, it must be fault-tolerant. Quantum computers undergo noise due to a phenomenon generally named quantum decoherence, a fault-tolerant quantum computer has the capabil- ity to suppress the effects of decoherence to an extent. For that to happen, a quantum computer should consider quantum error correction, a process in which decoherence is studied and attempted to be corrected. Within the context of quantum error correction, the information from quantum proces- sors is to be stored in a larger, more redundant system named a quantum error correcting code. Afterwards, one can obtain a vector named syndrome which provides partial information on the effect decoherence has had on a code. The process of recovering the decoherence or error that the code has undergone is named decoding. This thesis studies decoders for quan- tum error correcting codes, their performance, complexity and adaption to different types of quantum decoherence.
We discuss the connection between quantum error-correcting codes (QECCS) and algebraic coding theory. We start with an introduction to the relevant concepts of quantum mechanics, including the general error model. A quantum error-correcting code is a subspace of a complex Hilbert space, and its error-correcting properties are characterized by the Knill-Laflamme conditions. Using the stabilizer formalism, we illustrate how QECCs for can be constructed using techniques from algebraic coding theory. We also sketch how the information obtained via a quantum measurement can be interpreted as syndrome of the related classical code. Additionally, we present secondary constructions for QECCs, leading to propagation rules for the parameters of QECCs. This includes the puncture code by Rains and construction X for quantum codes.
In this paper, we utilize a concatenation scheme to construct new families of quantum error correction codes achieving the quantum Gilbert-Varshamov (GV) bound asymptotically. Weconcatenate alternant codes with any linear code achievingthe classical GV bound to construct Calderbank-Shor-Steane (CSS) codes. We show that the concatenated code can achieve the quantum GV bound asymptotically and can approach the Hashing bound for asymmetric Pauli channels. By combing Steane’s enlargement construction of CSS codes, we derive a family of enlarged stabilizer codes achieving the quantum GV bound for enlarged CSS codes asymptotically. Asapplications, we derive two families of fast encodable and decodable CSS codes with parametersQ1=[[N,Ω(N),Ω(N)]], andQ2=[[N,Ω(N/logN),Ω(N/logN)/Ω(logN)]]. We show thatQ1can be encoded very efficiently by circuits of sizeO(N)and depthO(N). For an input error syndrome,Q1can correct any adversarial error of weight up to half the minimum distance bound inO(N)time.Q1can also be decoded in parallel inO(N)time by usingO(N)classical processors. For an input error syndrome, we proved thatQ2can correct a linear number ofX-errors with high probability and an almost linear number ofZ-errors inO(N)time. Moreover,Q2can be decoded in parallel inO(log(N))time by usingO(N)classical processors.