AerPauliExpectation
class AerPauliExpectation
Bases: qiskit.opflow.expectations.expectation_base.ExpectationBase
An Expectation converter for using Aer’s operator snapshot to take expectations of quantum state circuits over Pauli observables.
Methods Defined Here
compute_variance
AerPauliExpectation.compute_variance(exp_op)
Compute the variance of the expectation estimator. Because Aer takes this expectation with 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 after sampling.
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
AerPauliExpectation.convert(operator)
Accept an Operator and return a new Operator with the Pauli measurements replaced by AerSnapshot-based expectation circuits.
Parameters
operator (OperatorBase) – The operator to convert. If it contains non-hermitian terms, the operator is decomposed into hermitian and anti-hermitian parts.
Return type
Returns
The converted operator.