Probabilistic programmable quantum processors with multiple copies of program states
Adam Brazier, Vladimír Bužek, P. L. Knight · Physical Review A · 2005
We examine the execution of general $\mathrm{U}(1)$ transformations on programmable quantum processors. We show that, with only the minimal assumption of availability of copies of the $1$-qubit program state, the apparent advantage of existing schemes proposed by G. Vidal et al. [Phys. Rev. Lett. 88, 047905 (2002)] and M. Hillery et al. [Phys. Rev. A 65, 022301 (2003)] to execute a general $\mathrm{U}(1)$ transformation with greater probability using complex program states appears not to hold.