40th Annual Symposium on Foundations of Computer Science Optimal Lower Bounds for Quantum Automata and Random Access Codes New York, New York October 17-October 18 ISBN: 0-7695-0409-4
Consider the finite regular language \math. In [3] it was shown that while this language is accepted by a deterministic finite automaton of size O(n), any one-way quantum finite automaton (QFA) for it has size \math . This was based on the fact that the evolution of a QFA is required to be reversible. When arbitrary intermediate measurements are allowed, this intuition breaks down. Nonetheless, we show a \math lower bound for such QFA for Ln , thus also improving the previous bound.The improved bound is obtained from simple entropy arguments based on Holevo's theorem [8]. This method also allows us to obtain an asymptotically optimal (1 - H(p))n bound for the dense quantum codes (random access codes) introduced in [3]. We then turn to Holevo's theorem, and show that in typical situations, it may be replaced by a tighter and more transparent in-probability bound.
Citation:
Ashwin Nayak, "Optimal Lower Bounds for Quantum Automata and Random Access Codes," focs, pp.369, 40th Annual Symposium on Foundations of Computer Science, 1999 Usage of this product signifies your acceptance of the Terms of Use. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||