qpe_toolbox.estimation.qft

Functions

qft_swapped(wires)	Generate the sequence of gates for a recursive QFT with reversed ordering.
iqft_swapped(wires)	Generate the inverse QFT gate sequence with reversed bit ordering.
qft(wires)	Generate the full Quantum Fourier Transform (QFT) gate sequence.
iqft(wires)	Generate the inverse Quantum Fourier Transform (IQFT) gate sequence.
count_gates_qft_swapped(m)	Compute the number of gates in the recursive QFT (reversed bit ordering).

Module Contents

qpe_toolbox.estimation.qft.qft_swapped(wires)

Generate the sequence of gates for a recursive QFT with reversed ordering.

The QFT is implemented recursively without final swaps. This routine is suitable for constructing circuits with qubit indices in reversed order.

Parameters:

wires (list[int]) – List of qubit indices on which to apply the QFT.

Returns:

List of gate instructions in the form (gate_label, *params, qubits...), where single-qubit gates are ('H', q), and controlled-phase gates are ('CPHASE', angle, target, control).

Return type:

list[tuple]

Notes

• Recursive implementation.

• No final SWAP gates are included.

• Use qft for standard bit ordering with swaps.

qpe_toolbox.estimation.qft.iqft_swapped(wires)

Generate the inverse QFT gate sequence with reversed bit ordering.

Parameters:

wires (list[int]) – List of qubit indices on which to apply the inverse QFT.

Returns:

Gate instructions for the inverse QFT, in the same format as qft_sw.

Return type:

list[tuple]

Notes

• Controlled-phase gates have their angles negated relative to qft_sw.

• No final SWAP gates are included.

qpe_toolbox.estimation.qft.qft(wires)

Generate the full Quantum Fourier Transform (QFT) gate sequence.

Parameters:

wires (list[int]) – List of qubit indices on which to apply the QFT.

Returns:

Gate instructions including Hadamard, controlled-phase, and final SWAP gates for normal bit ordering.

Return type:

list[tuple]

Notes

• Combines qft_sw with SWAP gates to reorder qubits to standard output order.

qpe_toolbox.estimation.qft.iqft(wires)

Generate the inverse Quantum Fourier Transform (IQFT) gate sequence.

Parameters:

wires (list[int]) – List of qubit indices on which to apply the IQFT.

Returns:

Gate instructions for the inverse QFT, including SWAPs.

Return type:

list[tuple]

Notes

• The angles of controlled-phase gates are negated relative to the QFT.

• Bit ordering should be checked if interfacing with other routines.

qpe_toolbox.estimation.qft.count_gates_qft_swapped(m)

Compute the number of gates in the recursive QFT (reversed bit ordering).

Parameters:

m (int) – Number of qubits in the QFT.

Returns:

Dictionary with keys: - 'H' : number of Hadamard gates - 'CPHASE' : number of controlled-phase gates

Return type:

dict[str, int]

Notes

• SWAP gates are not counted.

• Gate count corresponds to the reversed-output QFT.