 Abelian hidden-subgroup Fourier sampling

Measuring the coset state $|g_0+K⟩$ in the group shift operator eigenbasis samples uniformly from the annihilator of a subgroup of a finite abelian group $K^{\perp }$. Indeed,so the character-sum cancellation lemma gives probability $|K|/|G|$ on $K^{\perp }$ and zero elsewhere. The modulus of $\chi (g_0)$ is one, so the offset has no effect on the distribution.