workbench_algorithms.subroutines.alias_sampling

Functions for the alias sampling state preparation method.

AliasSampling

AliasSampling(
    qrom: QROM, usp: UniformStatePreparation, **kwargs
)

Bases: Qubrick

Qubrick for implementing alias sampling.

Parameters:

Name	Type	Description	Default
qrom	Qubrick	Data lookup instance.	required
usp	Qubrick	Uniform state preparation instance.	required
**kwargs	dict[str, Any]	Other arguments to pass to the init.	{}

compute_num_states staticmethod

compute_num_states(input_list)

Helper to compute number of states to prepare in alias sampling (works for symbolics & numerics).

Parameters:

Name	Type	Description	Default
input_list	list or SymbolicArray	List of coefficients to prepare.	required

Returns:

Type	Description
tuple	Number of states to prepare, and value to pad combined list by.

Raises:

Type	Description
ValueError	If the inputs are not the correct type for either numerics or symbolics.

compute

compute(
    prep_reg,
    input_list,
    bit_precision,
    lambda_val=None,
    ctrl: int = 0,
    **kwargs,
) -> None

State preparation by alias sampling.

Note

Uses the circuit in Fig. 11 of arXiv:1805.03662 .

Parameters:

Name	Type	Description	Default
prep_reg	Qubits or SymbolicQubits	Register to prepare coefficients onto.	required
input_list	list or SymbolicArray	List of coefficients to prepare.	required
bit_precision	int or Parameter	Number of bits to represent each coefficient.	required
lambda_val	int or Parameter	Power-of-two knob to trade off between gates and qubits. If None (default), then optimal lambda is calculated.	None
ctrl	Qubits, SymbolicQubits, or int	Control register. Defaults to no control, i.e. ctrl=0.	0
**kwargs	dict[str, Any]	Other arguments to pass to the compute.	{}