cirq.sample_density_matrix

Samples repeatedly from measurements in the computational basis.

cirq.sample_density_matrix(
    density_matrix: np.ndarray,
    indices: Sequence[int],
    *,
    qid_shape: Optional[Tuple[int, ...]] = None,
    repetitions: int = 1,
    seed: 'cirq.RANDOM_STATE_OR_SEED_LIKE' = None
) -> np.ndarray

Note that this does not modify the density_matrix.

density_matrix The density matrix to be measured. This matrix is assumed to be positive semidefinite and trace one. The matrix is assumed to be of shape (2 ** integer, 2 ** integer) or (2, 2, ..., 2).
indices Which qubits are measured. The density matrix rows and columns are assumed to be supplied in big endian order. That is the xth index of v, when expressed as a bitstring, has its largest values in the 0th index.
qid_shape The qid shape of the density matrix. Specify this argument when using qudits.
repetitions The number of times to sample the density matrix.
seed A seed for the pseudorandom number generator.

Measurement results with True corresponding to the |1⟩ state. The outer list is for repetitions, and the inner corresponds to measurements ordered by the supplied qubits. These lists are wrapped as a numpy ndarray.

ValueError repetitions is less than one or size of matrix is not a power of 2.
IndexError An index from indices is out of range, given the number of qubits corresponding to the density matrix.