44 research outputs found
Efficient Quantum Transforms
Quantum mechanics requires the operation of quantum computers to be unitary,
and thus makes it important to have general techniques for developing fast
quantum algorithms for computing unitary transforms. A quantum routine for
computing a generalized Kronecker product is given. Applications include
re-development of the networks for computing the Walsh-Hadamard and the quantum
Fourier transform. New networks for two wavelet transforms are given. Quantum
computation of Fourier transforms for non-Abelian groups is defined. A slightly
relaxed definition is shown to simplify the analysis and the networks that
computes the transforms. Efficient networks for computing such transforms for a
class of metacyclic groups are introduced. A novel network for computing a
Fourier transform for a group used in quantum error-correction is also given.Comment: 30 pages, LaTeX2e, 7 figures include
Essential idempotents and simplex codes
We define essential idempotents in group algebras and use them to prove that every mininmal abelian non-cyclic code is a repetition code. Also we use them to prove that every minimal abelian code is equivalent to a minimal cyclic code of the same length. Finally, we show that a binary cyclic code is simplex if and only if is of length of the form and is generated by an essential idempotent
Π‘ΡΡΡΠΊΡΡΡΠ° ΠΊΠΎΠ½Π΅ΡΠ½ΠΎΠΉ Π³ΡΡΠΏΠΏΠΎΠ²ΠΎΠΉ Π°Π»Π³Π΅Π±ΡΡ ΠΎΠ΄Π½ΠΎΠ³ΠΎ ΠΏΠΎΠ»ΡΠΏΡΡΠΌΠΎΠ³ΠΎ ΠΏΡΠΎΠΈΠ·Π²Π΅Π΄Π΅Π½ΠΈΡ Π°Π±Π΅Π»Π΅Π²ΡΡ Π³ΡΡΠΏΠΏ ΠΈ Π΅Ρ ΠΏΡΠΈΠ»ΠΎΠΆΠ΅Π½ΠΈΡ
In 1978 R. McEliece developed the first assymetric cryptosystem based on the use of Goppa's error-correctring codes and no effective key attacks has been described yet. Now there are many code-based cryptosystems known. One way to build them is to modify the McEliece cryptosystem by replacing Goppa's codes with other codes. But many variants of this modification were proven to be less secure.In connection with the development of quantum computing code cryptosystems along with lattice-based cryptosystems are considered as an alternative to number-theoretical ones. Therefore, it is relevant to find promising classes of codes that are applicable in cryptography. It seems that for this non-commutative group codes, i.e. left ideals in finite non-commutative group algebras, could be used.The Wedderburn theorem is useful to study non-commutative group codes. It implies the existence of an isomorphism of a semisimple group algebra onto a direct sum of matrix algebras. However, the specific form of the summands and the isomorphism construction are not explicitly defined by this theorem. Hence for each semisimple group algebra there is a task to explicitly construct its Wedderburn decomposition. This decomposition allows us to easily describe all left ideals of group algebra, i.e. group codes.In this paper we consider one semidirect product of abelian groups and the group algebra . In the case when and the Wedderburn decomposition of this algebra is constructed. In the case when field is of characteristic i.e. when this group algebra is not semisimple, a similar structure theorem is also obtained. Further in the paper, the primitive central idempotents of this group algebra are described. The obtained results are used to algebraically describe the group codes over Π 1978 Π³ΠΎΠ΄Ρ Π . ΠΠ°ΠΊ-ΠΠ»ΠΈΡΠΎΠΌ ΠΏΠΎΡΡΡΠΎΠ΅Π½Π° ΠΏΠ΅ΡΠ²Π°Ρ Π°ΡΠΈΠΌΠΌΠ΅ΡΡΠΈΡΠ½Π°Ρ ΠΊΠΎΠ΄ΠΎΠ²Π°Ρ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΠ°, ΠΎΡΠ½ΠΎΠ²Π°Π½Π½Π°Ρ Π½Π° ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠΈ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΡΡ
ΠΊΠΎΠ΄ΠΎΠ² ΠΠΎΠΏΠΏΡ, ΠΏΡΠΈ ΡΡΠΎΠΌ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΡΠ΅ Π°ΡΠ°ΠΊΠΈ Π½Π° ΡΠ΅ΠΊΡΠ΅ΡΠ½ΡΠΉ ΠΊΠ»ΡΡ ΡΡΠΎΠΉ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΡ Π΄ΠΎ ΡΠΈΡ
ΠΏΠΎΡ Π½Π΅ Π½Π°ΠΉΠ΄Π΅Π½Ρ. Π Π½Π°ΡΡΠΎΡΡΠ΅ΠΌΡ Π²ΡΠ΅ΠΌΠ΅Π½ΠΈ ΠΈΠ·Π²Π΅ΡΡΠ½ΠΎ ΠΌΠ½ΠΎΠ³ΠΎ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌ, ΠΎΡΠ½ΠΎΠ²Π°Π½Π½ΡΡ
Π½Π° ΡΠ΅ΠΎΡΠΈΠΈ ΠΏΠΎΠΌΠ΅Ρ
ΠΎΡΡΡΠΎΠΉΡΠΈΠ²ΠΎΠ³ΠΎ ΠΊΠΎΠ΄ΠΈΡΠΎΠ²Π°Π½ΠΈΡ. ΠΠ΄Π½ΠΈΠΌ ΠΈΠ· ΡΠΏΠΎΡΠΎΠ±ΠΎΠ² ΠΏΠΎΡΡΡΠΎΠ΅Π½ΠΈΡ ΡΠ°ΠΊΠΈΡ
ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΡ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΡ ΠΠ°ΠΊ-ΠΠ»ΠΈΡΠ° Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π·Π°ΠΌΠ΅Π½Ρ ΠΊΠΎΠ΄ΠΎΠ² ΠΠΎΠΏΠΏΡ Π½Π° Π΄ΡΡΠ³ΠΈΠ΅ ΠΊΠ»Π°ΡΡΡ ΠΊΠΎΠ΄ΠΎΠ². ΠΠ΄Π½Π°ΠΊΠΎ, ΠΈΠ·Π²Π΅ΡΡΠ½ΠΎ ΡΡΠΎ ΠΊΡΠΈΠΏΡΠΎΠ³ΡΠ°ΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΡΠΎΠΉΠΊΠΎΡΡΡ ΠΌΠ½ΠΎΠ³ΠΈΡ
ΡΠ°ΠΊΠΈΡ
ΠΌΠΎΠ΄ΠΈΡΠΈΠΊΠ°ΡΠΈΠΉ ΡΡΡΡΠΏΠ°Π΅Ρ ΡΡΠΎΠΉΠΊΠΎΡΡΠΈ ΠΊΠ»Π°ΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΡ ΠΠ°ΠΊ-ΠΠ»ΠΈΡΠ°. Π ΡΠ²ΡΠ·ΠΈ Ρ ΡΠ°Π·Π²ΠΈΡΠΈΠ΅ΠΌ ΠΊΠ²Π°Π½ΡΠΎΠ²ΡΡ
Π²ΡΡΠΈΡΠ»Π΅Π½ΠΈΠΉ ΠΊΠΎΠ΄ΠΎΠ²ΡΠ΅ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΡ, Π½Π°ΡΡΠ΄Ρ Ρ ΠΊΡΠΈΠΏΡΠΎΡΠΈΡΡΠ΅ΠΌΠ°ΠΌΠΌΠΈ Π½Π° ΡΠ΅ΡΡΡΠΊΠ°Ρ
, ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°ΡΡΡΡ ΠΊΠ°ΠΊ Π°Π»ΡΡΠ΅ΡΠ½Π°ΡΠΈΠ²Π° ΡΠ΅ΠΎΡΠ΅ΡΠΈΠΊΠΎ-ΡΠΈΡΠ»ΠΎΠ²ΡΠΌ. ΠΠΎΡΡΠΎΠΌΡ Π°ΠΊΡΡΠ°Π»ΡΠ½Π° Π·Π°Π΄Π°ΡΠ° ΠΏΠΎΠΈΡΠΊΠ° ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΡΡ
ΠΊΠ»Π°ΡΡΠΎΠ² ΠΊΠΎΠ΄ΠΎΠ², ΠΏΡΠΈΠΌΠ΅Π½ΠΈΠΌΡΡ
Π² ΠΊΡΠΈΠΏΡΠΎΠ³ΡΠ°ΡΠΈΠΈ. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»ΡΠ΅ΡΡΡ, ΡΡΠΎ Π΄Π»Ρ ΡΡΠΎΠ³ΠΎ ΠΌΠΎΠΆΠ½ΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°ΡΡ Π½Π΅ΠΊΠΎΠΌΠΌΡΡΠ°ΡΠΈΠ²Π½ΡΠ΅ Π³ΡΡΠΏΠΏΠΎΠ²ΡΠ΅ ΠΊΠΎΠ΄Ρ, Ρ.Π΅. Π»Π΅Π²ΡΠ΅ ΠΈΠ΄Π΅Π°Π»Ρ Π² ΠΊΠΎΠ½Π΅ΡΠ½ΡΡ
Π½Π΅ΠΊΠΎΠΌΠΌΡΡΠ°ΡΠΈΠ²Π½ΡΡ
Π³ΡΡΠΏΠΏΠΎΠ²ΡΡ
Π°Π»Π³Π΅Π±ΡΠ°Ρ
.ΠΠ»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ Π½Π΅ΠΊΠΎΠΌΠΌΡΡΠ°ΡΠΈΠ²Π½ΡΡ
Π³ΡΡΠΏΠΏΠΎΠ²ΡΡ
ΠΊΠΎΠ΄ΠΎΠ² ΠΏΠΎΠ»Π΅Π·Π½ΠΎΠΉ ΡΠ²Π»ΡΠ΅ΡΡΡ ΡΠ΅ΠΎΡΠ΅ΠΌΠ° ΠΠ΅Π΄Π΄Π΅ΡΠ±Π΅ΡΠ½Π°, Π΄ΠΎΠΊΠ°Π·ΡΠ²Π°ΡΡΠ°Ρ ΡΡΡΠ΅ΡΡΠ²ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΈΠ·ΠΎΠΌΠΎΡΡΠΈΠ·ΠΌΠ° Π³ΡΡΠΏΠΏΠΎΠ²ΠΎΠΉ Π°Π»Π³Π΅Π±ΡΡ Π½Π° ΠΏΡΡΠΌΡΡ ΡΡΠΌΠΌΡ ΠΌΠ°ΡΡΠΈΡΠ½ΡΡ
Π°Π»Π³Π΅Π±Ρ. ΠΠ΄Π½Π°ΠΊΠΎ ΠΊΠΎΠ½ΠΊΡΠ΅ΡΠ½ΡΠΉ Π²ΠΈΠ΄ ΡΠ»Π°Π³Π°Π΅ΠΌΡΡ
ΠΈ ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΡ ΠΈΠ·ΠΎΠΌΠΎΡΡΠΈΠ·ΠΌΠ° ΡΡΠΎΠΉ ΡΠ΅ΠΎΡΠ΅ΠΌΠΎΠΉ Π½Π΅ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½Ρ, ΠΈ ΠΏΠΎΡΡΠΎΠΌΡ Π΄Π»Ρ ΠΊΠ°ΠΆΠ΄ΠΎΠΉ Π³ΡΡΠΏΠΏΡ ΡΡΠΎΠΈΡ Π·Π°Π΄Π°ΡΠ° ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΠ²Π½ΠΎΠ³ΠΎ ΠΎΠΏΠΈΡΠ°Π½ΠΈΡ ΡΠ°Π·Π»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΠ΅Π΄Π΄Π΅ΡΠ±Π΅ΡΠ½Π°. ΠΡΠΎ ΡΠ°Π·Π»ΠΎΠΆΠ΅Π½ΠΈΠ΅ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ Π»Π΅Π³ΠΊΠΎ ΠΏΠΎΠ»ΡΡΠΈΡΡ Π²ΡΠ΅ Π»Π΅Π²ΡΠ΅ ΠΈΠ΄Π΅Π°Π»Ρ Π³ΡΡΠΏΠΏΠΎΠ²ΠΎΠΉ Π°Π»Π³Π΅Π±ΡΡ, Ρ.Π΅. Π³ΡΡΠΏΠΏΠΎΠ²ΡΠ΅ ΠΊΠΎΠ΄Ρ. Π ΡΠ°Π±ΠΎΡΠ΅ ΡΠ°ΡΡΠΌΠ°ΡΡΠΈΠ²Π°Π΅ΡΡΡ ΠΏΠΎΠ»ΡΠΏΡΡΠΌΠΎΠ΅ ΠΏΡΠΎΠΈΠ·Π²Π΅Π΄Π΅Π½ΠΈΠ΅ Π°Π±Π΅Π»Π΅Π²ΡΡ
Π³ΡΡΠΏΠΏ ΠΈ ΠΊΠΎΠ½Π΅ΡΠ½Π°Ρ Π³ΡΡΠΏΠΏΠΎΠ²Π°Ρ Π°Π»Π³Π΅Π±ΡΠ° ΡΡΠΎΠΉ Π³ΡΡΠΏΠΏΡ. ΠΠ»Ρ ΡΡΠΎΠΉ Π°Π»Π³Π΅Π±ΡΡ ΠΏΡΠΈ ΡΡΠ»ΠΎΠ²ΠΈΡΡ
ΠΈ ΠΏΠΎΡΡΡΠΎΠ΅Π½ΠΎ ΡΠ°Π·Π»ΠΎΠΆΠ΅Π½ΠΈΠ΅ ΠΠ΅Π΄Π΄Π΅ΡΠ±ΡΡΠ½Π°. Π ΡΠ»ΡΡΠ°Π΅ ΠΏΠΎΠ»Ρ ΡΡΡΠ½ΠΎΠΉ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ, ΠΊΠΎΠ³Π΄Π° ΡΡΠ° Π³ΡΡΠΏΠΏΠΎΠ²Π°Ρ Π°Π»Π³Π΅Π±ΡΠ° Π½Π΅ ΡΠ²Π»ΡΠ΅ΡΡΡ ΠΏΠΎΠ»ΡΠΏΡΠΎΡΡΠΎΠΉ, ΡΠ°ΠΊΠΆΠ΅ ΠΏΠΎΠ»ΡΡΠ΅Π½Π° ΡΡ
ΠΎΠ΄Π½Π°Ρ ΡΡΡΡΠΊΡΡΡΠ½Π°Ρ ΡΠ΅ΠΎΡΠ΅ΠΌΠ°. ΠΠΏΠΈΡΠ°Π½Ρ Π²ΡΠ΅ Π½Π΅ΡΠ°Π·Π»ΠΎΠΆΠΈΠΌΡΠ΅ ΡΠ΅Π½ΡΡΠ°Π»ΡΠ½ΡΠ΅ ΠΈΠ΄Π΅ΠΌΠΏΠΎΡΠ΅Π½ΡΡ ΡΡΠΎΠΉ Π³ΡΡΠΏΠΏΠΎΠ²ΠΎΠΉ Π°Π»Π³Π΅Π±ΡΡ. ΠΠΎΠ»ΡΡΠ΅Π½Π½ΡΠ΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΡΡΡΡΡ Π΄Π»Ρ Π°Π»Π³Π΅Π±ΡΠ°ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΎΠΏΠΈΡΠ°Π½ΠΈΡ Π²ΡΠ΅Ρ
Π³ΡΡΠΏΠΏΠΎΠ²ΡΡ
ΠΊΠΎΠ΄ΠΎΠ² Π½Π°Π΄ Q_{m,n}.$
Group algebras and coding theory: a short survey
We study codes constructed from ideals in group algebras and we are particularly interested in their dimensions and weights. First we introduced a special kind of idempotents and study the ideals they generate.
We use this information to show that there exist abelian non-cyclic groups that give codes which are more convenient than the cyclic ones. Finally, we discuss briefly some facts about non-abelian codes