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On the generation of multiplicative groups by small primes
Abstract
Motivated by a question of Regev arising from his improved quantum factoring algorithm, we study how many small primes are needed to generate the group (ℤ/qℤ)× when each prime may be used with exponent only $0$ or $1$. We prove that, for every fixed ε>0 and A>0, there is an absolute constant C* and a set of at most (log Q)1+ε primes, all at most (log Q)C*(A+1), such that for all but O(Q(log Q)−A) (with the implied constant depending only on ε and A) integers q≤ Q, every element of (ℤ/qℤ)× is a product of a subset of these primes modulo q. The exponent 1+ε in the number of primes is best possible up to the arbitrary ε in the exponent.
Related
BibTeX
@misc{klurman2026generation,
title = {{On the generation of multiplicative groups by small primes}},
author = {Oleksiy Klurman and Igor E. Shparlinski and Joni Teräväinen},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.25393},
eprint = {2609.25393},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25393},
}
RIS
TY - UNPB
TI - On the generation of multiplicative groups by small primes
AU - Oleksiy Klurman
AU - Igor E. Shparlinski
AU - Joni Teräväinen
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.25393
UR - https://arxiv.org/abs/2609.25393
AB - Motivated by a question of Regev arising from his improved quantum factoring algorithm, we study how many small primes are needed to generate the group (ℤ/qℤ)^× when each prime may be used with exponent only $0$ or $1$. We prove that, for every fixed ε>0 and A>0, there is an absolute constant C_* and a set of at most (log Q)^1+ε primes, all at most (log Q)^C_*(A+1), such that for all but O(Q(log Q)^−A) (with the implied constant depending only on ε and A) integers q≤ Q, every element of (ℤ/qℤ)^× is a product of a subset of these primes modulo q. The exponent 1+ε in the number of primes is best possible up to the arbitrary ε in the exponent.
ER -