MatrixExpectation
class MatrixExpectation
Bases: ExpectationBase
Deprecated: An Expectation converter which converts Operator measurements to be matrix-based so they can be evaluated by matrix multiplication.
The class qiskit.opflow.expectations.matrix_expectation.MatrixExpectation
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.
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.
Returns
The variances or lists thereof (if exp_op contains ListOps) of the expectation value estimation, equal to 0.
Return type
list | float
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.
Returns
The converted operator.
Return type