Authors
William J Huggins, Kianna Wan, Jarrod McClean, Thomas E O’Brien, Nathan Wiebe, Ryan Babbush
Publication date
2022/12/5
Journal
Physical Review Letters
Volume
129
Issue
24
Pages
240501
Publisher
American Physical Society
Description
Many quantum algorithms involve the evaluation of expectation values. Optimal strategies for estimating a single expectation value are known, requiring a number of state preparations that scales with the target error ϵ as O (1/ϵ). In this Letter, we address the task of estimating the expectation values of M different observables, each to within additive error ϵ, with the same 1/ϵ dependence. We describe an approach that leverages Gilyén et al.’s quantum gradient estimation algorithm to achieve O (M/ϵ) scaling up to logarithmic factors, regardless of the commutation properties of the M observables. We prove that this scaling is worst-case optimal in the high-precision regime if the state preparation is treated as a black box, even when the operators are mutually commuting. We highlight the flexibility of our approach by presenting several generalizations, including a strategy for accelerating the estimation of a collection …
Total citations
2021202220232024171911
Scholar articles
WJ Huggins, K Wan, J McClean, TE O'Brien, N Wiebe… - Physical Review Letters, 2022