- class qiskit.opflow.expectations.MatrixExpectation#
An Expectation converter which converts Operator measurements to be matrix-based so they can be evaluated by matrix multiplication.
Deprecated since version 0.24.0: The class
qiskit.opflow.expectations.matrix_expectation.MatrixExpectationis 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.
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.