MaximumLikelihoodAmplitudeEstimation
class qiskit.algorithms.MaximumLikelihoodAmplitudeEstimation(evaluation_schedule, minimizer=None, quantum_instance=None, sampler=None)
Bases: AmplitudeEstimator
The Maximum Likelihood Amplitude Estimation algorithm.
This class implements the quantum amplitude estimation (QAE) algorithm without phase estimation, as introduced in [1]. In comparison to the original QAE algorithm [2], this implementation relies solely on different powers of the Grover operator and does not require additional evaluation qubits. Finally, the estimate is determined via a maximum likelihood estimation, which is why this class in named MaximumLikelihoodAmplitudeEstimation.
References
[1]: Suzuki, Y., Uno, S., Raymond, R., Tanaka, T., Onodera, T., & Yamamoto, N. (2019).
Amplitude Estimation without Phase Estimation. arXiv:1904.10246(opens in a new tab).
[2]: Brassard, G., Hoyer, P., Mosca, M., & Tapp, A. (2000).
Quantum Amplitude Amplification and Estimation. arXiv:quant-ph/0005055(opens in a new tab).
qiskit.algorithms.amplitude_estimators.mlae.MaximumLikelihoodAmplitudeEstimation.__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(opens in a new tab) for a migration guide.
Parameters
- evaluation_schedule (list(opens in a new tab)[int(opens in a new tab)] | int(opens in a new tab)) – If a list, the powers applied to the Grover operator. The list element must be non-negative. If a non-negative integer, an exponential schedule is used where the highest power is 2 to the integer minus 1: [id, Q^2^0, …, Q^2^(evaluation_schedule-1)].
- minimizer (MINIMIZER | None) – A minimizer used to find the minimum of the likelihood function. Defaults to a brute search where the number of evaluation points is determined according to
evaluation_schedule. The minimizer takes a function as first argument and a list of (float, float) tuples (as bounds) as second argument and returns a single float which is the found minimum. - quantum_instance (QuantumInstance |Backend | None) – Deprecated: Quantum Instance or Backend
- sampler (BaseSampler | None) – A sampler primitive to evaluate the circuits.
Raises
ValueError(opens in a new tab) – If the number of oracle circuits is smaller than 1.
Attributes
quantum_instance
Deprecated. Get the quantum instance.
The property qiskit.algorithms.amplitude_estimators.mlae.MaximumLikelihoodAmplitudeEstimation.quantum_instance is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. See https://qisk.it/algo_migration(opens in a new tab) for a migration guide.
Returns
The quantum instance used to run this algorithm.
sampler
Get the sampler primitive.
Returns
The sampler primitive to evaluate the circuits.
Methods
compute_confidence_interval
static compute_confidence_interval(result, alpha, kind='fisher', apply_post_processing=False)
Compute the alpha confidence interval using the method kind.
The confidence level is (1 - alpha) and supported kinds are ‘fisher’, ‘likelihood_ratio’ and ‘observed_fisher’ with shorthand notations ‘fi’, ‘lr’ and ‘oi’, respectively.
Parameters
- result (MaximumLikelihoodAmplitudeEstimationResult) – A maximum likelihood amplitude estimation result.
- alpha (float(opens in a new tab)) – The confidence level.
- kind (str(opens in a new tab)) – The method to compute the confidence interval. Defaults to ‘fisher’, which computes the theoretical Fisher information.
- apply_post_processing (bool(opens in a new tab)) – If True, apply post-processing to the confidence interval.
Returns
The specified confidence interval.
Raises
- AlgorithmError – If run() hasn’t been called yet.
- NotImplementedError(opens in a new tab) – If the method kind is not supported.
Return type
tuple(opens in a new tab)[float(opens in a new tab), float(opens in a new tab)]
compute_mle
compute_mle(circuit_results, estimation_problem, num_state_qubits=None, return_counts=False)
Compute the MLE via a grid-search.
This is a stable approach if sufficient gridpoints are used.
Parameters
- circuit_results (list(opens in a new tab)[dict(opens in a new tab)[str(opens in a new tab), int(opens in a new tab)] | np.ndarray]) – A list of circuit outcomes. Can be counts or statevectors.
- estimation_problem (EstimationProblem) – The estimation problem containing the evaluation schedule and the number of likelihood function evaluations used to find the minimum.
- num_state_qubits (int(opens in a new tab) | None) – The number of state qubits, required for statevector simulations.
- return_counts (bool(opens in a new tab)) – If True, returns the good counts.
Returns
The MLE for the provided result object.
Return type
float(opens in a new tab) | tuple(opens in a new tab)[float(opens in a new tab), list(opens in a new tab)[float(opens in a new tab)]]
construct_circuits
construct_circuits(estimation_problem, measurement=False)
Construct the Amplitude Estimation w/o QPE quantum circuits.
Parameters
- estimation_problem (EstimationProblem) – The estimation problem for which to construct the QAE circuit.
- measurement (bool(opens in a new tab)) – Boolean flag to indicate if measurement should be included in the circuits.
Returns
A list with the QuantumCircuit objects for the algorithm.
Return type
list(opens in a new tab)[qiskit.circuit.quantumcircuit.QuantumCircuit]
estimate
estimate(estimation_problem)
Run the amplitude estimation algorithm on provided estimation problem.
Parameters
estimation_problem (EstimationProblem) – The estimation problem.
Returns
An amplitude estimation results object.
Raises
- ValueError(opens in a new tab) – A quantum instance or Sampler must be provided.
- AlgorithmError – If state_preparation is not set in estimation_problem.
- AlgorithmError – Sampler job run error
Return type