MatrixExpectation
class MatrixExpectation
Bases: qiskit.opflow.expectations.expectation_base.ExpectationBase
An Expectation converter which converts Operator measurements to be matrix-based so they can be evaluated by matrix multiplication.
Methods Defined Here
compute_variance
MatrixExpectation.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.
Parameters
exp_op (OperatorBase) – The full expectation value Operator.
Return type
Union[list, float]
Returns
The variances or lists thereof (if exp_op contains ListOps) of the expectation value estimation, equal to 0.
convert
MatrixExpectation.convert(operator)
Accept an Operator and return a new Operator with the Pauli measurements replaced by Matrix based measurements.
Parameters
operator (OperatorBase) – The operator to convert.
Return type
Returns
The converted operator.