Struct Observable 

pub struct Observable<R: RealField, const D: usize> { /* private fields */ }

A named projector carrying its own read-out.

This is the measurement boundary of the verdict law: the only site at which a verdict enters a QCL pipeline. Every stage upstream carries operators; here a state meets a projection and a number comes out, through the shipped born_projective_probability, or a Prob through born_projective_prob. The observable folds no verdicts itself, because the fold rule depends on which kind of verdict a world carries; it exposes its Projection so that adjudicate can ask commutes_with of a pair before folding projection-valued verdicts.

Implementations

impl<R, const D: usize> Observable<R, D>

where R: RealField + FromPrimitive + Default + Debug,

pub fn new(name: impl Into<String>, projection: Projection<R, D>) -> Self

A named observable over a validated projection.

pub fn from_ket( name: impl Into<String>, ket: &CausalTensor<Complex<R>>, ) -> Result<Self, QuantumError>

The rank-1 observable |ψ⟩⟨ψ| of a ket, validated by the shipped Projection::from_ket.

Errors

As Projection::from_ket: a ket of the wrong shape or dimension, or a near-zero ket.

pub fn read_out(&self, plant: &QuantumPlant<R>) -> Result<R, QuantumError>

The Born probability Tr(Pρ) on the plant’s state, in [0, 1].

Errors

QuantumError::DimensionMismatch naming both dimensions when the plant’s dim() differs from D, which is the error born_projective_probability already raises.

pub fn read_out_prob( &self, plant: &QuantumPlant<R>, ) -> Result<Prob, QuantumError>

where R: Into<f64>,

The read-out as the Prob verdict, the boundary where the number becomes a classical proposition.

Errors

As read_out.

pub fn sample( &self, plant: &QuantumPlant<R>, shots: u64, seed: u64, ) -> Result<CountHistogram, QuantumError>

shots samples of the accepting outcome at seed, drawn from the Born probability this observable reads out. Outcome 1 is “accepted”, 0 is “rejected”.

Errors

As read_out; nothing is drawn on the error path.

impl<R: RealField, const D: usize> Observable<R, D>

pub fn name(&self) -> &str

The name.

pub fn projection(&self) -> &Projection<R, D>

The projection, for adjudicate’s commutation guard.

pub fn dim(&self) -> usize

Always D.

Trait Implementations

impl<R: Clone + RealField, const D: usize> Clone for Observable<R, D>

fn clone(&self) -> Observable<R, D>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<R: Debug + RealField, const D: usize> Debug for Observable<R, D>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<R, const D: usize> Default for Observable<R, D>

where R: RealField + FromPrimitive + Default + Debug,

The zero projection under an empty name, because the causal monad requires a Default for every value it carries.

fn default() -> Self

Returns the “default value” for a type.