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workbench_algorithms.subroutines.multiplexing.binary_tree

Qubrick for binary search multiplexing.

BinaryTreeMultiplexor 

BinaryTreeMultiplexor(**kwargs)

Bases: Qubrick

Optimized multiplexing based on Fig. 7 in arXiv:1805.03662.

compute 

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

Compute the binary tree multiplexing circuit.

We account for various cases:

  1. There is no data to load (exit the routine).
  2. Loading a single item does not require this hefty machinery.
  3. Loading two items without a control is similarly cheap to the single-item-case.
  4. Loading n > 2 items without a control.
  5. Loading n > 1 items with a control.

The bottom two cases are handled by calling workhorse methods in this class.

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