cirq.SimulationState

State and context for an operation acting on a state tensor.

Inherits From: SimulationStateBase

cirq.SimulationState(
    *,
    state: TState,
    prng: (np.random.RandomState | None) = None,
    qubits: (Sequence[cirq.Qid] | None) = None,
    classical_data: (cirq.ClassicalDataStore | None) = None
)

prng The pseudo random number generator to use for probabilistic effects.
qubits Determines the canonical ordering of the qubits. This is often used in specifying the initial state, i.e. the ordering of the computational basis states.
classical_data The shared classical data container for this simulation.
state The underlying quantum state of the simulation.

allows_factoring Subclasses that allow factorization should override this.
can_represent_mixed_states

classical_data

log_of_measurement_results Gets the log of measurement results.
prng

qubit_map

qubits

Methods

add_qubits

View source

add_qubits(
    qubits: Sequence[cirq.Qid]
) -> Self

Add qubits in the |0> state to a new state space and take the kron product.

Args
qubits Sequence of qubits to be added.

Returns
NotImplemented If the subclass does not implement this method.
Self A cirq.SimulationState with qubits added or self if there are no qubits to add.

apply_operation

View source

apply_operation(
    op: cirq.Operation
)

copy

View source

copy(
    deep_copy_buffers: bool = True
) -> Self

Creates a copy of the object.

Args
deep_copy_buffers If True, buffers will also be deep-copied. Otherwise the copy will share a reference to the original object's buffers.

Returns
A copied instance.

create_merged_state

View source

create_merged_state() -> Self

Creates a final merged state.

factor

View source

factor(
    qubits: Sequence[cirq.Qid], *, validate=True, atol=1e-07, inplace=False
) -> tuple[Self, Self]

Splits two state spaces after a measurement or reset.

get_axes

View source

get_axes(
    qubits: Sequence[cirq.Qid]
) -> list[int]

kronecker_product

View source

kronecker_product(
    other: Self, *, inplace=False
) -> Self

Joins two state spaces together.

measure

View source

measure(
    qubits: Sequence[cirq.Qid],
    key: str,
    invert_mask: Sequence[bool],
    confusion_map: dict[tuple[int, ...], np.ndarray]
)

Measures the qubits and records to log_of_measurement_results.

Any bitmasks will be applied to the measurement record.

Args
qubits The qubits to measure.
key The key the measurement result should be logged under. Note that operations should only store results under keys they have declared in a _measurement_key_names_ method.
invert_mask The invert mask for the measurement.
confusion_map The confusion matrices for the measurement.

Raises
ValueError If a measurement key has already been logged to a key.

remove_qubits

View source

remove_qubits(
    qubits: Sequence[cirq.Qid]
) -> Self

Remove qubits from the state space.

The qubits to be removed should be untangled from rest of the system and in the |0> state.

Args
qubits Sequence of qubits to be removed.

Returns
NotImplemented If the subclass does not implement this method.
Self A cirq.SimulationState with qubits removed or self if there are no qubits to remove.

rename

View source

rename(
    q1: cirq.Qid, q2: cirq.Qid, *, inplace=False
)

Renames q1 to q2.

Args
q1 The qubit to rename.
q2 The new name.
inplace True to rename the qubit in the current object, False to create a copy with the qubit renamed.

Returns
The original object with the qubits renamed if inplace is requested, or a copy of the original object with the qubits renamed otherwise.

Raises
ValueError If the qubits are of different dimensionality.

sample

View source

sample(
    qubits: Sequence[cirq.Qid],
    repetitions: int = 1,
    seed: cirq.RANDOM_STATE_OR_SEED_LIKE = None
) -> np.ndarray

Samples the state value.

swap

View source

swap(
    q1: cirq.Qid, q2: cirq.Qid, *, inplace=False
)

Swaps two qubits.

This only affects the index, and does not modify the underlying state.

Args
q1 The first qubit to swap.
q2 The second qubit to swap.
inplace True to swap the qubits in the current object, False to create a copy with the qubits swapped.

Returns
The original object with the qubits swapped if inplace is requested, or a copy of the original object with the qubits swapped otherwise.

Raises
ValueError If the qubits are of different dimensionality.

transpose_to_qubit_order

View source

transpose_to_qubit_order(
    qubits: Sequence[cirq.Qid], *, inplace=False
) -> Self

Physically reindexes the state by the new basis.

Args
qubits The desired qubit order.
inplace True to perform this operation inplace.

Returns
The state with qubit order transposed and underlying representation updated.

Raises
ValueError If the provided qubits do not match the existing ones.

__getitem__

View source

__getitem__(
    item: (cirq.Qid | None)
) -> Self

Gets the item associated with the qubit.

__iter__

View source

__iter__() -> Iterator[cirq.Qid | None]

Iterates the keys of the mapping.

__len__

View source

__len__() -> int

Gets the number of items in the mapping.