cirq.ProjectorSum

List of mappings representing a sum of projector operators.

cirq.ProjectorSum(
    linear_dict: Optional[value.LinearDict[FrozenSet[Tuple[raw_types.Qid, int]]]] = None
)

linear_dict A linear dictionary from a set of tuples of (Qubit, integer) to a complex number. The tuple is a projector onto the qubit and the complex number is the weight of these projections.

qubits

Methods

copy

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copy() -> 'ProjectorSum'

expectation_from_density_matrix

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expectation_from_density_matrix(
    state: np.ndarray,
    qid_map: Mapping[cirq.Qid, int]
) -> float

Expectation of the sum of projections from a density matrix.

Projects the density matrix onto the sum of projectors and computes the expectation of the measurements.

Args
state An array representing a valid density matrix.
qid_map A map from all qubits used in this ProjectorSum to the indices of the qubits that state_vector is defined over.

Returns
The expectation value of the input state.

expectation_from_state_vector

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expectation_from_state_vector(
    state_vector: np.ndarray,
    qid_map: Mapping[cirq.Qid, int]
) -> float

Compute the expectation value of this ProjectorSum given a state vector.

Projects the state vector onto the sum of projectors and computes the expectation of the measurements.

Args
state_vector An array representing a valid state vector.
qid_map A map from all qubits used in this ProjectorSum to the indices of the qubits that state_vector is defined over.

Returns
The expectation value of the input state.

from_projector_strings

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@classmethod
from_projector_strings(
    terms: Union[ProjectorString, List[ProjectorString]]
) -> 'ProjectorSum'

Builds a ProjectorSum from one or more ProjectorString(s).

Args
terms Either a single ProjectorString or a list of ProjectorStrings.

Returns
A ProjectorSum.

matrix

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matrix(
    projector_qids: Optional[Iterable[raw_types.Qid]] = None
) -> csr_matrix

Returns the matrix of self in computational basis of qubits.

Args
projector_qids Ordered collection of qubits that determine the subspace in which the matrix representation of the ProjectorSum is to be computed. Qbits absent from self.qubits are acted on by the identity. Defaults to the qubits of the projector_dict.

Returns
A sparse matrix that is the projection in the specified basis.

__add__

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__add__(
    other: Union['ProjectorString', 'ProjectorSum']
)

__bool__

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__bool__() -> bool

__eq__

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__eq__(
    other: _SupportsValueEquality
) -> bool

__iter__

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__iter__()

__len__

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__len__() -> int

__mul__

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__mul__(
    other: value.Scalar
)

__ne__

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__ne__(
    other: _SupportsValueEquality
) -> bool

__neg__

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__neg__()

__rmul__

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__rmul__(
    other: value.Scalar
)

__sub__

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__sub__(
    other: Union['ProjectorString', 'ProjectorSum']
)

__truediv__

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__truediv__(
    a: value.Scalar
)