Quantum Lower Bounds for Fanout (2003)
by
M. Fang
,
S. Fenner
,
F. Green
,
S. Homer
,
Y. Zhang
| Citations: | 7 - 2 self |
BibTeX
@MISC{Fang03quantumlower,
author = {M. Fang and S. Fenner and F. Green and S. Homer and Y. Zhang},
title = {Quantum Lower Bounds for Fanout},
year = {2003}
}
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Abstract
We prove several new lower bounds for constant depth quantum circuits. The main result is that parity (and hence fanout) requires log depth circuits, when the circuits are composed of single qubit and arbitrary size Tooli gates, and when they use only constantly many ancill. Under this constraint, this bound is close to optimal. In the case of a nonconstant number a of ancill and n input qubits, we give a tradeo between a and the required depth, that results in a non-trivial lower bound for fanout when a = n 1 o(1) .
