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PauliExpectation

class PauliExpectation(group_paulis=True)[source]

Bases: qiskit.opflow.expectations.expectation_base.ExpectationBase

An Expectation converter for Pauli-basis observables by changing Pauli measurements to a diagonal ({Z, I}^n) basis and appending circuit post-rotations to the measured state function. Optionally groups the Paulis with the same post-rotations (those that commute with one another, or form Abelian groups) into single measurements to reduce circuit execution overhead.

Parameters

group_paulis (bool) – Whether to group the Pauli measurements into commuting sums, which all have the same diagonalizing circuit.

Methods Defined Here

compute_variance

Compute the variance of the expectation estimator.

convert

Accepts an Operator and returns a new Operator with the Pauli measurements replaced by diagonal Pauli post-rotation based measurements so they can be evaluated by sampling and averaging.