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Corpus ID: 227053529

Topological obstructions to implementing controlled unknown unitaries

@article{Gavorova2020TopologicalOT,
title={Topological obstructions to implementing controlled unknown unitaries},
author={Zuzana Gavorov'a and M. Seidel and Y. Touati},
journal={arXiv: Quantum Physics},
year={2020}
}

Is a quantum algorithm capable of implementing an if-clause? Given a black-box subroutine, a $d$-dimensional unitary $U\in U(d)$, a quantum if-clause would correspond to applying it to an input qudit if and only if the value of a control qubit is $1$. It was previously shown by Thompson et al. and Araujo et al. that implementations using single access to the oracle $U$ are impossible. Our main result is a strong generalization of this impossibility result: we prove that there is no unitary… CONTINUE READING