cirq.StabilizerStateChForm

A representation of stabilizer states using the CH form,

Inherits From: StabilizerState, QuantumStateRepresentation

cirq.StabilizerStateChForm(
    num_qubits: int, initial_state: int = 0
) -> None

\\(|\psi> = \omega U_C U_H |s>\\)

This representation keeps track of overall phase.

Reference: https://arxiv.org/abs/1808.00128

num_qubits The number of qubits in the system.
initial_state The computational basis representation of the state as a big endian int.

can_represent_mixed_states Subclasses that can represent mixed states should override this.
supports_factor Subclasses that allow factorization should override this.

Methods

apply_cx

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apply_cx(
    control_axis: int,
    target_axis: int,
    exponent: float = 1,
    global_shift: float = 0
)

Apply a CX operation to the state.

Args
control_axis The control axis of the operation.
target_axis The axis to which the operation should be applied.
exponent The exponent of the CX operation, must be an integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not an integer.

apply_cz

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apply_cz(
    control_axis: int,
    target_axis: int,
    exponent: float = 1,
    global_shift: float = 0
)

Apply a CZ operation to the state.

Args
control_axis The control axis of the operation.
target_axis The axis to which the operation should be applied.
exponent The exponent of the CZ operation, must be an integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not an integer.

apply_global_phase

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apply_global_phase(
    coefficient: value.Scalar
)

Apply a global phase to the state.

Args
coefficient The global phase to apply.

apply_h

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apply_h(
    axis: int, exponent: float = 1, global_shift: float = 0
)

Apply an H operation to the state.

Args
axis The axis to which the operation should be applied.
exponent The exponent of the H operation, must be an integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not an integer.

apply_x

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apply_x(
    axis: int, exponent: float = 1, global_shift: float = 0
)

Apply an X operation to the state.

Args
axis The axis to which the operation should be applied.
exponent The exponent of the X operation, must be a half-integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not half-integer.

apply_y

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apply_y(
    axis: int, exponent: float = 1, global_shift: float = 0
)

Apply an Y operation to the state.

Args
axis The axis to which the operation should be applied.
exponent The exponent of the Y operation, must be a half-integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not half-integer.

apply_z

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apply_z(
    axis: int, exponent: float = 1, global_shift: float = 0
)

Apply a Z operation to the state.

Args
axis The axis to which the operation should be applied.
exponent The exponent of the Z operation, must be a half-integer.
global_shift The global phase shift of the raw operation, prior to exponentiation. Typically the value in gate.global_shift.

Raises
ValueError If the exponent is not half-integer.

copy

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copy(
    deep_copy_buffers: bool = True
) -> 'cirq.StabilizerStateChForm'

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.

factor

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factor(
    axes: Sequence[int], *, validate=True, atol=1e-07
) -> Tuple[TSelf, TSelf]

Splits two state spaces after a measurement or reset.

inner_product_of_state_and_x

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inner_product_of_state_and_x(
    x: int
) -> Union[float, complex]

Returns the amplitude of x'th element of the state vector, i.e.

kron

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kron(
    other: 'cirq.StabilizerStateChForm'
) -> 'cirq.StabilizerStateChForm'

Joins two state spaces together.

measure

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measure(
    axes: Sequence[int], seed: 'cirq.RANDOM_STATE_OR_SEED_LIKE' = None
) -> List[int]

Measures the state.

Args
axes The axes to measure.
seed The random number seed to use.

Returns
The measurements in order.

project_Z

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project_Z(
    q, z
)

Applies a Z projector on the q'th qubit.

Returns: a normalized state with Z_q |psi> = z |psi>

reindex

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reindex(
    axes: Sequence[int]
) -> 'cirq.StabilizerStateChForm'

Physically reindexes the state by the new basis.

Args
axes The desired axis order.

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

sample

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

Samples the state. Subclasses can override with more performant method.

Args
axes The axes to sample.
repetitions The number of samples to make.
seed The random number seed to use.

Returns
The samples in order.

state_vector

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state_vector() -> np.ndarray

to_state_vector

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to_state_vector() -> np.ndarray

update_sum

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update_sum(
    t, u, delta=0, alpha=0
)

Implements the transformation (Proposition 4 in Bravyi et al)

i^alpha U_H (|t> + i^delta |u>) = omega W_C W_H |s'>

__eq__

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__eq__(
    other: _SupportsValueEquality
) -> bool

__ne__

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__ne__(
    other: _SupportsValueEquality
) -> bool