workbench_algorithms.subroutines.multiplexing.cond_clean

Qubrick for conditionally clean multiplexing.

ConditionallyCleanMultiplexor

Bases: Qubrick

Multiplexor utilizing conditionally clean construction as presented in arxiv:2407.17966.

See Figure 9 in reference. This qubrick works by constructing the first relevant index as aggregated conditions and then applies the corresponding data conditioned on this. Then it sequentially moves through the relevant indices by finding the MSB difference, undoing the structure to this point, and then redo-ing with the new condition utiliing the partial_compute() function.

Notes

This should be called with the filter '>>hermitian-window-filter>>' to take advantage of the cancellations that occur when you replace one condition with the next. This does the minimal work before calling the filter without hardcoding the cancellations with a maximum filter window required that is linear in the number of qubits in index register. Hardcoding like in the BinaryTreeMultiplexor requires more care as gates that begin each layer in the conditionally clean structure include adjacent bits such that the gate that switches branch for bit i, will need to be aware of the higher bit (i-1) to apply the correct cancellation.

compute

compute(
    index_reg: Qubits,
    multiplex_function: Callable,
    used_indices: list[int] | None = None,
    ctrl: Qubits | int = 0,
)

Compute the serial multiplexing circuit.

Parameters:

Name	Type	Description	Default
index_reg	Qubits	Qubit register storing the values over which the multiplexing is performed.	required
multiplex_function	callable	A function which takes an index and then index register and performs the operation associated with that index.	required
used_indices	list	List of indices corresponding to terms where the operators are actually being applied.	None
ctrl	(int, Qubits)	Control for \(\text{SELECT}\). Defaults to 0.	0