  Since the publication of the Quantum Amplitude Estimation (QAE) algorithm by
Brassard et al., 2002, several variations have been proposed, such as Aaronson
et al., 2019, Grinko et al., 2019, and Suzuki et al., 2020. The main difference
between the original and the variants is the exclusion of Quantum Phase
Estimation (QPE) by the latter. This difference is notable given that QPE is
the key component of original QAE, but is composed of many operations
considered expensive for the current NISQ era devices. We compare two recently
proposed variants (Grinko et al., 2019 and Suzuki et al., 2020) by implementing
them on the IBM Quantum device using Qiskit, an open source framework for
quantum computing. We analyze and discuss advantages of each algorithm from the
point of view of their implementation and performance on a quantum computer.
