sample_density_matrix(density_matrix: numpy.ndarray, indices: List[int], *, qid_shape: Optional[Tuple[int, …]] = None, repetitions: int = 1, seed: cirq.RANDOM_STATE_OR_SEED_LIKE = None) → numpy.ndarray¶
Samples repeatedly from measurements in the computational basis.
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 an numpy ndarray.
repetitionsis less than one or size of
matrixis not a power of 2.
IndexError – An index from
indicesis out of range, given the number of qubits corresponding to the density matrix.