Harry Buhrman, Ronald de Wolf. Quantum zero-error algorithms cannot be composed. Inf. Process. Lett., 87(2):79-84, 2003. [doi]
@article{BuhrmanW03,
title = {Quantum zero-error algorithms cannot be composed},
author = {Harry Buhrman and Ronald de Wolf},
year = {2003},
doi = {10.1016/S0020-0190(03)00254-0},
url = {http://dx.doi.org/10.1016/S0020-0190(03)00254-0},
researchr = {https://researchr.org/publication/BuhrmanW03},
cites = {0},
citedby = {0},
journal = {Inf. Process. Lett.},
volume = {87},
number = {2},
pages = {79-84},
}