Source code for qolumbina.programs.is_two_power.is_two_power_qubit

# This code is developed through cross-language conversion from 
# https://github.com/MgcosA/Code_of_Testing_Oracle_Quantum_Program_Article/blob/master/qolumbina/programs/Is2Power.qs
# 
# In detail, the raw program is written in Q#, and we rewrite it in Qiskit.

from qiskit import QuantumCircuit, QuantumRegister

# ---------- benchmark registration ----------
from ..benchmark_registry import register_benchmark
from pathlib import Path
@register_benchmark(
    Path(__file__).stem,
    family=Path(__file__).resolve().parent.name,
    description="Check if input is a power of two (qubit version)",
    class_name="Is2PowerQubit",
    source={
        "repo": "https://github.com/MgcosA/Code_of_Testing_Oracle_Quantum_Program_Article/blob/master/",
        "file": "qolumbina/programs/Is2Power.qs",
        "sdk": "Q#",
        "available_doc": True
    },
    testability_refactoring=[
        "Cross-language translation", 
        "Structure reorganization"
    ] 
)
def create_is_two_power_qubit(input_qubits):
    return Is2PowerQubit(input_qubits=input_qubits)




class Is2PowerQubit(QuantumCircuit):
    r"""
    Qubit version of ``Is2Power_Q`` operation.

    Acts on n input qubits and 1 target qubit.
    Flips the target qubit when the input qubits represent a power of 2,
    following the original Q# ``Is2Power_Q`` logic.
    """
    def __init__(self, input_qubits: int, name: str | None = None):
        r"""
        Args:
            input_qubits: Number of qubits in the input register (:math:`n`).
            name: Optional name for the circuit.
        """

        self._input_qubits = input_qubits

        # ---------- registers ----------
        q_input = QuantumRegister(input_qubits, "q")
        q_target = QuantumRegister(1, "target")

        super().__init__(q_input, q_target, name=name or "Is2Power_Q")
        self._build()

    # ---------- build ----------
    def _build(self) -> None:
        qs = self.qregs[0]
        qtarget = self.qregs[1][0]

        n = len(qs)

        # MultiX on input qubits -> MultiX(qs)
        for q in qs:
            self.x(q)

        # Loop over input qubits
        for i in range(n):
            self.x(qs[i])

            # Multi-controlled X on target -> Controlled X(qs, qtarget)
            # All input qubits control the target
            self.mcx(qs, qtarget)

            self.x(qs[i])

        # Uncompute MultiX on input qubits -> MultiX(qs)
        for q in qs:
            self.x(q)