Title
Classical Lower Bounds from Quantum Upper Bounds
Abstract
We prove lower bounds on complexity measures, such as the approximate degree of a Boolean function and the approximate rank of a Boolean matrix, using quantum arguments. We prove these lower bounds using a quantum query algorithm for the combinatorial group testing problem. We show that for any function f, the approximate degree of computing the OR of n copies of f is Omega(sqrt n) times the approximate degree of f, which is optimal. No such general result was known prior to our work, and even the lower bound for the OR of ANDs function was only resolved in 2013. We then prove an analogous result in communication complexity, showing that the logarithm of the approximate rank (or more precisely, the approximate gamma-2 norm) of F: X x Y to 0,1 grows by a factor of Omega (sqrtn) when we take the OR of n copies of F, which is also essentially optimal. As a corollary, we give a new proof of Razborov's celebrated Omega(sqrtn) lower bound on the quantum communication complexity of the disjointness problem. Finally, we generalize both these results from composition with the OR function to composition with arbitrary symmetric functions, yielding nearly optimal lower bounds in this setting as well.
Year
DOI
Venue
2018
10.1109/FOCS.2018.00040
2018 IEEE 59th Annual Symposium on Foundations of Computer Science (FOCS)
Keywords
DocType
Volume
quantum computing,computational complexity
Conference
abs/1807.06256
ISSN
ISBN
Citations 
1523-8288
978-1-5386-4231-3
0
PageRank 
References 
Authors
0.34
34
4
Name
Order
Citations
PageRank
Shalev Ben-David1638.92
Adam Bouland2215.74
Ankit Garg312516.19
Robin Kothari419621.05