qiskit.aqua.operators.expectations.AerPauliExpectation
class AerPauliExpectation
An Expectation converter for using Aer’s operator snapshot to take expectations of quantum state circuits over Pauli observables.
__init__
__init__()
Initialize self. See help(type(self)) for accurate signature.
Methods
__init__() | Initialize self. |
compute_variance(exp_op) | Compute the variance of the expectation estimator. |
convert(operator) | Accept an Operator and return a new Operator with the Pauli measurements replaced by AerSnapshot-based expectation circuits. |
compute_variance
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
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.
Return type
OperatorBase
Returns
The converted operator.