Title
Explicit Lower Bounds on Strong Quantum Simulation
Abstract
We consider the problem of classical strong (amplitude-wise) simulation of n-qubit quantum circuits, and identify a subclass of simulators we call monotone. This subclass encompasses almost all prominent simulation techniques. We prove an unconditional (i.e. without relying on any complexity-theoretic assumptions) and explicit (n - 2)(2n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> - 1) lower bound on the running time of simulators within this subclass. Assuming the Strong Exponential Time Hypothesis (SETH), we further remark that a universal simulator computing any amplitude to precision 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-n</sup> /2 must take at least 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n-o(n)</sup> time. We then compare strong simulators to existing SAT solvers, and identify the time-complexity below which a strong simulator would improve on state-of-the-art general SAT solving. Finally, we investigate Clifford+T quantum circuits with t T-gates. Using the sparsification lemma, we identify a time complexity lower bound of 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2.2451×10-8t</sup> below which a strong simulator would improve on state-of-the-art 3-SAT solving. This also yields a conditional exponential lower bound on the growth of the stabilizer rank of magic states.
Year
DOI
Venue
2018
10.1109/TIT.2020.3004427
IEEE Transactions on Information Theory
Keywords
Field
DocType
Quantum computing,computational complexity,circuit simulation
Quantum,Discrete mathematics,Upper and lower bounds,Quantum simulator,Amplitude,Mathematics,Monotone polygon,Exponential time hypothesis
Journal
Volume
Issue
ISSN
66
9
0018-9448
Citations 
PageRank 
References 
1
0.36
2
Authors
3
Name
Order
Citations
PageRank
Cupjin Huang141.13
Michael Newman210.36
Mario Szegedy33358325.80