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Classical algorithms for quantum mean values
[article]
2019
arXiv
pre-print
We consider the task of estimating the expectation value of an n-qubit tensor product observable O_1⊗ O_2⊗...⊗ O_n in the output state of a shallow quantum circuit. This task is a cornerstone of variational quantum algorithms for optimization, machine learning, and the simulation of quantum many-body systems. Here we study its computational complexity for constant-depth quantum circuits and three types of single-qubit observables O_j which are (a) close to the identity, (b) positive
arXiv:1909.11485v1
fatcat:u5uxit3xrvepfbnfdc5zel3hme