CVaRMeasurement¶

class CVaRMeasurement(*args, **kwargs)[source]¶

Bases: OperatorStateFn

Deprecated: A specialized measurement class to compute CVaR expectation values.: See https://arxiv.org/pdf/1907.04769.pdf for further details.

Used in CVaRExpectation, see there for more details.

0.24.0 ভার্সন থেকে ডেপ্রিকেটেড: The class qiskit.opflow.state_fns.cvar_measurement.CVaRMeasurement is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration.

প্যারামিটার

primitive -- The OperatorBase which defines the diagonal operator measurement.
coeff -- A coefficient by which to multiply the state function
alpha -- A real-valued parameter between 0 and 1 which specifies the fraction of observed samples to include when computing the objective value. alpha = 1 corresponds to a standard observable expectation value. alpha = 0 corresponds to only using the single sample with the lowest energy. alpha = 0.5 corresponds to ranking each observation by lowest energy and using the best

রেইজেস

ValueError -- TODO remove that this raises an error
ValueError -- If alpha is not in [0, 1].
OpflowError -- If the primitive is not diagonal.

Methods Defined Here

`add`	Return Operator addition of self and other, overloaded by `+`.
`adjoint`	The adjoint of a CVaRMeasurement is not defined.
`compute_cvar`	Given the energies of each sampled measurement outcome (H_i) as well as the sampling probability of each measurement outcome (p_i, we can compute the CVaR.
`eval`	Given the energies of each sampled measurement outcome (H_i) as well as the sampling probability of each measurement outcome (p_i, we can compute the CVaR as H_j + 1/α(sum_i<j p_i(H_i - H_j)).
`eval_variance`	Given the energies of each sampled measurement outcome (H_i) as well as the sampling probability of each measurement outcome (p_i, we can compute the variance of the CVaR estimator as H_j^2 + 1/α * (sum_i<j p_i*(H_i^2 - H_j^2)).
`get_outcome_energies_probabilities`	In order to compute the CVaR of an observable expectation, we require the energies of each sampled measurement outcome as well as the sampling probability of each measurement outcome.
`mul`	Returns the scalar multiplication of the Operator, overloaded by `*`, including support for Terra's `Parameters`, which can be bound to values later (via `bind_parameters`).
`sample`	Sample the state function as a normalized probability distribution.
`tensor`	Return tensor product between self and other, overloaded by `^`.
`to_circuit_op`	Not defined.
`to_density_matrix`	Not defined.
`to_matrix`	Not defined.
`to_matrix_op`	Not defined.
`traverse`	Apply the convert_fn to the internal primitive if the primitive is an Operator (as in the case of `OperatorStateFn`).

Attributes

INDENTATION = ' '¶

alpha¶

A real-valued parameter between 0 and 1 which specifies the: fraction of observed samples to include when computing the objective value. alpha = 1 corresponds to a standard observable expectation value. alpha = 0 corresponds to only using the single sample with the lowest energy. alpha = 0.5 corresponds to ranking each observation by lowest energy and using the best half.

রিটার্নস: The parameter alpha which was given at initialization

coeff¶: A coefficient by which the state function is multiplied.

instance_id¶: Return the unique instance id.

is_measurement¶: Whether the StateFn object is a measurement Operator.

num_qubits¶

parameters¶

primitive: OperatorBase¶: The primitive which defines the behavior of the underlying State function.

settings¶: Return settings.