2006/03/01 by Ivanyos, Gabor
#FOS: Physical sciences #Quantum Physics (quant-ph)
paper · doi:10.48550/arxiv.quant-ph/0603009
We say that collection of n-qudit gates is universal if there exists N0≥ n such that for every N≥ N0 every N-qudit unitary operation can be approximated with arbitrary precision by a circuit built from gates of the collection. Our main result is an upper bound on the smallest N0 with the above property. The bound is roughly d8 n, where d is the number of levels of the base system (the 'd' in the term qudit.) The proof is based on a recent result on invariants of (finite) linear groups.