Documentation version

PauliY¶

from cascaqit import PauliY

PauliY ¶

PauliY(
    target: str, *, name: str | None = None
) -> Observable

Create a Pauli Y declaration on target and return Observable. Target is a logical name such as "q0", not a qubit index. Name is optional and defaults to a form such as Y(q0).

Y probes complex phase information; computational-basis counts alone cannot recover its expectation. Its positive eigenstate is (|0⟩ + i|1⟩)/sqrt(2).

from cascaqit import PauliY

observable = PauliY("q0", name="Y0")
assert observable.targets == ("q0",)
assert observable.bases[0].value == "Y"

Empty names or targets, including surrounding whitespace, fail construction. This function creates a declaration only. Evaluation must also check that target exists; read estimator_kind to distinguish exact calculation from sampling. See Observable batches.