EnergyVariance

class pulser.backend.EnergyVariance(*, evaluation_times=None, tag_suffix=None)

Bases: Observable

Stores the variance of the Hamiltonian at the evaluation times.

The variance of the Hamiltonian at time t is calculated by <φ(t)|H(t)^2|φ(t)> - <φ(t)|H(t)|φ(t)>^2

Parameters:

• evaluation_times (Sequence[float] | None, default: None) – The relative times at which to compute the variance. If left as None, uses the default_evaluation_times of the backend’s EmulationConfig.

• tag_suffix (str | None, default: None) – An optional suffix to append to the tag. Needed if multiple instances of the same observable are given to the same EmulationConfig.

Attributes

tag	Label for the observable, used to index the Results object.
uuid	A universal unique identifier for this instance.

Methods

apply

Calculates the observable to store in the Results.

Signatures

apply(*, state, hamiltonian, **kwargs)

Calculates the observable to store in the Results.

Return type:

Any

property tag: str

Label for the observable, used to index the Results object.

Within a Results instance, all computed observables must have different tags.

Returns:

The tag of the observable.

property uuid: UUID

A universal unique identifier for this instance.