workbench_algorithms.experimental.subroutines.state_preparation.alias_sampling

Class and functions for the alias sampling state preparation method (PREP with garbage).

AliasSampling

AliasSampling(
    qrom: QROM,
    usp: UniformStatePreparation,
    lambda_val=None,
    **kwargs,
)

Bases: Qubrick

Qubrick for implementing alias sampling.

Parameters:

Name	Type	Description	Default
`qrom`	`QROM`	Data lookup instance.	required
`usp`	`UniformStatePreparation`	Uniform state preparation instance.	required
`lambda_val`	`int`	SEL-SWAP tunable parameter for QROM, default to None where optimal lambda (based on Toffoli counts) is calculated	`None`
`**kwargs`	`dict[str, Any]`	Other arguments to pass to the init.	`{}`

compute

compute(
    psi: Qubits,
    data: StatePrepDataInterface,
    ctrl: Qubits | int = 0,
    *,
    usp_rotator: Qubits | None = None,
    coin_toss_reg: Qubits | None = None,
)

State preparation by alias sampling.

Note

Uses the circuit in Fig. 11 of arXiv:1805.03662 <https://arxiv.org/abs/1805.03662>_.

Parameters:

Name	Type	Description	Default
`psi`	`Qubits`	Register to prepare coefficients onto.	required
`data`	`StatePrepDataInterface`	a data storage interface that hold all the classical precomputation numbers	required
`ctrl`	`Qubits \| int`	Control register.	`0`
`usp_rotator`	`Qubits \| None`	Qubit to rotate as part of USP. Needs to be supplied if this Qubrick is used with a coherent uncomputation (such as in LCU), but will be allocated on the fly if not supplied.	`None`
`coin_toss_reg`	`Qubits \| None`	Qubits register used to load the coin toss state (uniform state) in for the alias sampling protocol. Needs to be supplied if this Qubrick is used with a coherent uncomputation (such as in LCU), but will be allocated on the fly if not supplied.	`None`