qiskit.opflow.expectations.MatrixExpectation

class MatrixExpectation

An Expectation converter which converts Operator measurements to be matrix-based so they can be evaluated by matrix multiplication.

__init__()

Initialize self. See help(type(self)) for accurate signature.

Methods

__init__()	Initialize self.
compute_variance(exp_op)	Compute the variance of the expectation estimator.
convert(operator)	Accept an Operator and return a new Operator with the Pauli measurements replaced by Matrix based measurements.

compute_variance(exp_op)

Compute the variance of the expectation estimator. Because this expectation works by matrix multiplication, the estimation is exact and the variance is always 0, but we need to return those values in a way which matches the Operator’s structure.

パラメータ

exp_op (OperatorBase) – The full expectation value Operator.

戻り値の型

Union[list, float]

戻り値

The variances or lists thereof (if exp_op contains ListOps) of the expectation value estimation, equal to 0.

convert(operator)

Accept an Operator and return a new Operator with the Pauli measurements replaced by Matrix based measurements.

パラメータ

operator (OperatorBase) – The operator to convert.

戻り値の型

OperatorBase

戻り値

The converted operator.