cirq.ops.PauliSum

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Represents operator defined by linear combination of PauliStrings.

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Main aliases

cirq.PauliSum, cirq.ops.linear_combinations.PauliSum

cirq.ops.PauliSum(
    linear_dict: Optional[value.LinearDict[UnitPauliStringT]] = None
)

Since PauliStrings store their own coefficients, this class does not implement the LinearDict interface. Instead, you can add and subtract terms and then iterate over the resulting (simplified) expression.

Under the hood, this class is backed by a LinearDict with coefficient-less PauliStrings as keys. PauliStrings are reconstructed on-the-fly during iteration.

Attributes
qubits

Methods

copy

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copy() -> "PauliSum"

expectation_from_density_matrix

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expectation_from_density_matrix(
    state: np.ndarray,
    qubit_map: Mapping[cirq.ops.Qid, int],
    *,
    atol: float = 1e-07,
    check_preconditions: bool = True
) -> float

Evaluate the expectation of this PauliSum given a density matrix.

See PauliString.expectation_from_density_matrix.

Args
state	An array representing a valid density matrix.
qubit_map	A map from all qubits used in this PauliSum to the indices of the qubits that state is defined over.
atol	Absolute numerical tolerance.
check_preconditions	Whether to check that state represents a valid density matrix.

Returns
The expectation value of the input state.

expectation_from_state_vector

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expectation_from_state_vector(
    state_vector: np.ndarray,
    qubit_map: Mapping[cirq.ops.Qid, int],
    *,
    atol: float = 1e-07,
    check_preconditions: bool = True
) -> float

Evaluate the expectation of this PauliSum given a state vector.

See PauliString.expectation_from_state_vector.

Args
state	An array representing a valid state vector.
qubit_map	A map from all qubits used in this PauliSum to the indices of the qubits that state_vector is defined over.
atol	Absolute numerical tolerance.
check_preconditions	Whether to check that state_vector represents a valid state vector.

Returns
The expectation value of the input state.

expectation_from_wavefunction

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expectation_from_wavefunction(
    state: np.ndarray,
    qubit_map: Mapping[cirq.ops.Qid, int],
    *,
    atol: float = 1e-07,
    check_preconditions: bool = True
) -> float

THIS FUNCTION IS DEPRECATED.

IT WILL BE REMOVED IN cirq v0.10.0.

Use expectation_from_state_vector instead.

from_pauli_strings

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@classmethod
from_pauli_strings(
    terms: Union[PauliString, List[PauliString]]
) -> "PauliSum"

matrix

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matrix() -> np.ndarray

Reconstructs matrix of self from underlying Pauli operations.

Raises
TypeError	if any of the gates in self does not provide a unitary.

wrap

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@staticmethod
wrap(
    val: cirq.ops.PauliSumLike
) -> "PauliSum"

__add__

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__add__(
    other
)

__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: cirq.ops.PauliSumLike
)

__ne__

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__ne__(
    other: _SupportsValueEquality
) -> bool

__neg__

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__neg__()

__pow__

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__pow__(
    exponent: int
)

__radd__

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__radd__(
    other
)

__rmul__

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__rmul__(
    other: cirq.ops.PauliSumLike
)

__rsub__

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__rsub__(
    other
)

__sub__

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__sub__(
    other
)

__truediv__

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__truediv__(
    a: cirq.value.Scalar
)