BQUInt

qualtran.BQUInt

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Unsigned integer whose values are bounded within a range.

Inherits From: QDType, QCDType

qualtran.BQUInt(
    bitsize, iteration_length=NOTHING
)

LCU methods often make use of coherent for-loops via UnaryIteration, iterating over a range of values stored as a superposition over the SELECT register. Such (nested) coherent for-loops can be represented using a Tuple[Register(dtype=BQUInt), ...] where the i’th entry stores the bitsize and iteration length of i’th nested for-loop.

One useful feature when processing such nested for-loops is to flatten out a composite index, represented by a tuple of indices (i, j, …), one for each selection register into a single integer that can be used to index a flat target register. An example of such a mapping function is described in Eq.45 of https://arxiv.org/abs/1805.03662. A general version of this mapping function can be implemented using numpy.ravel_multi_index and numpy.unravel_index.

For example

Attributes

bitsize

The number of qubits used to represent the integer.

iteration_length

The length of the iteration range.

num_bits

 

num_cbits

Number of classical bits required to represent a single instance of this data type.

num_qubits

Number of qubits required to represent a single instance of this data type.

Methods

is_symbolic

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is_symbolic() -> bool

Returns True if this dtype is parameterized with symbolic objects.

get_classical_domain

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get_classical_domain() -> Iterable[Any]

Yields all possible classical (computational basis state) values representable by this type.

assert_valid_classical_val

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assert_valid_classical_val(
    val: int, debug_str: str = 'val'
)

Raises an exception if val is not a valid classical value for this type.

Args

val

A classical value that should be in the domain of this QDType.

debug_str

Optional debugging information to use in exception messages.

to_bits

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to_bits(
    x: int
) -> List[int]

Yields individual bits corresponding to binary representation of x

from_bits

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from_bits(
    bits: Sequence[int]
) -> int

Combine individual bits to form x

assert_valid_classical_val_array

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assert_valid_classical_val_array(
    val_array: NDArray[np.integer], debug_str: str = 'val'
)

Raises an exception if val_array is not a valid array of classical values for this type.

Often, validation on an array can be performed faster than validating each element individually.

Args

val_array

A numpy array of classical values. Each value should be in the domain of this QDType.

debug_str

Optional debugging information to use in exception messages.

__ne__

__ne__(
    other
)

Check equality and either forward a NotImplemented or return the result negated.

__eq__

__eq__(
    other
)

Method generated by attrs for class BQUInt.