cirq.CSwapGate

A controlled swap gate. The Fredkin gate.

Inherits From: InterchangeableQubitsGate, Gate

Methods

controlled

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controlled(
    num_controls: (int | None) = None,
    control_values: (cv.AbstractControlValues | Sequence[int | Collection[int]] | None) = None,
    control_qid_shape: (tuple[int, ...] | None) = None
) -> raw_types.Gate

Returns a controlled SWAP with one additional control.

The controlled method of the Gate class, of which this class is a child, returns a ControlledGate with sub_gate = self. This method overrides this behavior to return a ControlledGate with sub_gate = SWAP.

num_qubits

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num_qubits() -> int

The number of qubits this gate acts on.

on

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on(
    *qubits
) -> cirq.Operation

Returns an application of this gate to the given qubits.

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

Returns: a cirq.Operation which is this gate applied to the given qubits.

on_each

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

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

Args
*targets The qubits to apply this gate to. For single-qubit gates this can be provided as varargs or a combination of nested iterables. For multi-qubit gates this must be provided as an Iterable[Sequence[Qid]], where each sequence has num_qubits qubits.

Returns
Operations applying this gate to the target qubits.

Raises
ValueError If targets are not instances of Qid or Iterable[Qid]. If the gate qubit number is incompatible.
TypeError If a single target is supplied and it is not iterable.

qubit_index_to_equivalence_group_key

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qubit_index_to_equivalence_group_key(
    index
)

Returns a key that differs between non-interchangeable qubits.

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.

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

with_probability

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

Creates a probabilistic channel with this gate.

Args
probability floating point value between 0 and 1, giving the probability this gate is applied.

Returns
cirq.RandomGateChannel that applies self with probability probability and the identity with probability 1-p.

wrap_in_linear_combination

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wrap_in_linear_combination(
    coefficient: cirq.TParamValComplex = 1
) -> cirq.LinearCombinationOfGates

Returns a LinearCombinationOfGates with this gate.

Args
coefficient number coefficient to use in the resulting cirq.LinearCombinationOfGates object.

Returns
cirq.LinearCombinationOfGates containing self with a coefficient of coefficient.

__add__

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__add__(
    other: (Gate | cirq.LinearCombinationOfGates)
) -> cirq.LinearCombinationOfGates

__call__

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__call__(
    *qubits, **kwargs
)

Call self as a function.

__eq__

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__eq__(
    other: _SupportsValueEquality
) -> bool

__mul__

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__mul__(
    other: complex
) -> 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
)

__rmul__

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__rmul__(
    other: complex
) -> cirq.LinearCombinationOfGates

__sub__

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__sub__(
    other: (Gate | cirq.LinearCombinationOfGates)
) -> cirq.LinearCombinationOfGates

__truediv__

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__truediv__(
    other: complex
) -> cirq.LinearCombinationOfGates