cirq.ops.IdentityGate

A Gate that perform no operation on qubits.

Inherits From: SupportsOnEachGate, Gate

cirq.ops.IdentityGate(
    num_qubits: Optional[int] = None,
    qid_shape: Optional[Tuple[int, ...]] = None
) -> None

Used in the notebooks

Used in the guide

The unitary matrix of this gate is a diagonal matrix with all 1s on the diagonal and all 0s off the diagonal in any basis.

cirq.I is the single qubit identity gate.

ValueError If the length of qid_shape doesn't equal num_qubits.

Methods

controlled

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controlled(
    num_controls: int = None,
    control_values: Optional[Sequence[Union[int, Collection[int]]]] = None,
    control_qid_shape: Optional[Tuple[int, ...]] = None
) -> "Gate"

Returns a controlled version of this gate. If no arguments are specified, defaults to a single qubit control.

num_controls: Total number of control qubits. control_values: For which control qubit values to apply the sub gate. A sequence of length num_controls where each entry is an integer (or set of integers) corresponding to the qubit value (or set of possible values) where that control is enabled. When all controls are enabled, the sub gate is applied. If unspecified, control values default to 1. control_qid_shape: The qid shape of the controls. A tuple of the expected dimension of each control qid. Defaults to (2,) * num_controls. Specify this argument when using qudits.

num_qubits

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num_qubits() -> int

The number of qubits this gate acts on.

on

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on(
    *qubits
) -> "Operation"

Returns an application of this gate to the given qubits.

Args
*qubits The collection of qubits to potentially apply the gate to.

on_each

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on_each(
    *targets
) -> List[cirq.ops.Operation]

Returns a list of operations applying the gate to all targets.

Args
*targets The qubits to apply this gate to.

Returns
Operations applying this gate to the target qubits.

Raises
ValueError if targets are not instances of Qid or List[Qid]. ValueError if the gate operates on two or more Qids.

validate_args

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validate_args(
    qubits: Sequence['cirq.Qid']
) -> None

Checks if this gate can be applied to the given qubits.

By default checks that:

  • inputs are of type Qid
  • len(qubits) == num_qubits()
  • qubit_i.dimension == qid_shape[i] for all qubits

Child classes can override. The child implementation should call super().validate_args(qubits) then do custom checks.

Args
qubits The sequence of qubits to potentially apply the gate to.

Throws:

  • ValueError: The gate can't be applied to the qubits.

with_probability

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with_probability(
    probability: "cirq.TParamVal"
) -> "cirq.Gate"

wrap_in_linear_combination

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wrap_in_linear_combination(
    coefficient: Union[complex, float, int] = 1
) -> "cirq.LinearCombinationOfGates"

__add__

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__add__(
    other: Union['Gate', 'cirq.LinearCombinationOfGates']
) -> "cirq.LinearCombinationOfGates"

__call__

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__call__(
    *args, **kwargs
)

Call self as a function.

__eq__

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__eq__(
    other: _SupportsValueEquality
) -> bool

__mul__

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__mul__(
    other: Union[complex, float, int]
) -> "cirq.LinearCombinationOfGates"

__ne__

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__ne__(
    other: _SupportsValueEquality
) -> bool

__neg__

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__neg__() -> "cirq.LinearCombinationOfGates"

__pow__

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__pow__(
    power: Any
) -> Any

__rmul__

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__rmul__(
    other: Union[complex, float, int]
) -> "cirq.LinearCombinationOfGates"

__sub__

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__sub__(
    other: Union['Gate', 'cirq.LinearCombinationOfGates']
) -> "cirq.LinearCombinationOfGates"

__truediv__

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__truediv__(
    other: Union[complex, float, int]
) -> "cirq.LinearCombinationOfGates"