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# FasterAmplitudeEstimation¶

class FasterAmplitudeEstimation(delta, maxiter, rescale=True, quantum_instance=None, sampler=None)[source]

The Faster Amplitude Estimation algorithm.

The Faster Amplitude Estimation (FAE) [1] algorithm is a variant of Quantum Amplitude Estimation (QAE), where the Quantum Phase Estimation (QPE) by an iterative Grover search, similar to [2].

Due to the iterative version of the QPE, this algorithm does not require any additional qubits, as the originally proposed QAE [3] and thus the resulting circuits are less complex.

References

[1]: K. Nakaji. Faster Amplitude Estimation, 2020;

arXiv:2002.02417

[2]: D. Grinko et al. Iterative Amplitude Estimation, 2019;

arXiv:1912.05559

[3]: G. Brassard et al. Quantum Amplitude Amplification and Estimation, 2000;

arXiv:quant-ph/0005055

Parameters
• delta (float) – The probability that the true value is outside of the final confidence interval.

• maxiter (int) – The number of iterations, the maximal power of Q is 2 ** (maxiter - 1).

• rescale (bool) – Whether to rescale the problem passed to estimate.

• quantum_instance (QuantumInstance | Backend | None) – Pending deprecation: The quantum instance or backend to run the circuits.

• sampler (BaseSampler | None) – A sampler primitive to evaluate the circuits.

Note

This algorithm overwrites the number of shots set in the quantum_instance argument, but will reset them to the initial number after running.

Methods

 construct_circuit Construct the circuit $$Q^k X |0\rangle>$$. estimate Run the amplitude estimation algorithm on provided estimation problem.

Attributes

quantum_instance

Pending deprecation; Get the quantum instance.

Return type

QuantumInstance | None

Returns

The quantum instance used to run this algorithm.

sampler

Get the sampler primitive.

Return type

BaseSampler | None

Returns

The sampler primitive to evaluate the circuits.