Full Quantum State

Using with_state_tomography() instructs the backend to return the full quantum state vector (or density matrix) after execution.

from qilisdk.readout import Readout
from qilisdk.backends import QiliSim
from qilisdk.digital import Circuit
from qilisdk.functionals import DigitalPropagation

backend = QiliSim()
functional = DigitalPropagation(Circuit(2))

spec = Readout().with_state_tomography()
result = backend.execute(functional, readout=spec)

state = result.get_state()           # The full ket or density matrix as a QTensor
probs = result.get_probabilities()   # A dict[str, float] derived from |amplitudes|²

Parameters

• method (Literal["exact"], default "exact"): Tomography method. Currently only "exact" is supported, such that the backend returns the raw state vector.

When to Use It

Use state tomography when you need the complete quantum state for post-processing: computing custom observables offline, visualising the state, checking fidelity, or seeding the next step of a multi-step algorithm.

Note

State tomography is only available on simulators. Physical QPUs (accessed via SpeQtrum) do not support this readout type.