IterativePhaseEstimation¶

class IterativePhaseEstimation(num_iterations, quantum_instance=None, sampler=None)[source]¶

Bases: PhaseEstimator

Run the Iterative quantum phase estimation (QPE) algorithm.

Given a unitary circuit and a circuit preparing an eigenstate, return the phase of the eigenvalue as a number in \([0,1)\) using the iterative phase estimation algorithm.

[1]: Dobsicek et al. (2006), Arbitrary accuracy iterative phase estimation algorithm as a two: qubit benchmark, arxiv/quant-ph/0610214

Deprecated since version 0.24.0: qiskit.algorithms.phase_estimators.ipe.IterativePhaseEstimation.__init__()'s argument quantum_instance is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. Instead, use the sampler argument. See https://qisk.it/algo_migration for a migration guide.

Parameters

num_iterations (int) -- The number of iterations (rounds) of the phase estimation to run.
quantum_instance (QuantumInstance | Backend | None) -- Deprecated: The quantum instance on which the circuit will be run.
sampler (BaseSampler | None) -- The sampler primitive on which the circuit will be sampled.

Raises

ValueError -- if num_iterations is not greater than zero.
AlgorithmError -- If neither sampler nor quantum instance is provided.

Methods

`construct_circuit`	Construct the kth iteration Quantum Phase Estimation circuit.
`estimate`	Estimate the eigenphase of the input unitary and initial-state pair.