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

default_aggregation_method
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.