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MultiControlToffoli

QuICT.core.gate.MultiControlToffoli 

MultiControlToffoli(aux_usage='no_aux')

Bases: object

Divided by the usages of auxiliary qubits, here are 4 implementations of multi-control Toffoli gates.

Detailed description of each synthesis algorithm could be found in the backend.

Parameters:

  • aux_usage (str, default: 'no_aux' ) –

    4 different usages of auxiliary qubits could be chosen, as listed 'no_aux': No auxiliary qubits are used

    'one_clean_aux': 1 clean auxiliary qubit is used

    'one_dirty_aux': 1 dirty auxiliary qubit is used

    'half_dirty_aux': more than half of all qubits are used as auxiliary qubits, which could be dirty

Source code in QuICT/core/gate/multicontrol_toffoli.py 
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def __init__(self, aux_usage='no_aux'):
    """
    Args:
        aux_usage (str): 4 different usages of auxiliary qubits could be chosen, as listed
            'no_aux': No auxiliary qubits are used  \n
            'one_clean_aux': 1 clean auxiliary qubit is used  \n
            'one_dirty_aux': 1 dirty auxiliary qubit is used  \n
            'half_dirty_aux': more than half of all qubits are used as auxiliary qubits, which could be dirty
    """
    assert aux_usage in self.__AUX_USAGES, TypeError("MultiControlToffoli.aux_usage", self.__AUX_USAGES, aux_usage)

    self.aux_usage = aux_usage

__call__ 

__call__(control, aux=0) -> CompositeGate

By default, the qubit arrangement would be control qubits, target qubit, auxiliary qubits (if exists)

Parameters:

  • control (int) –

    the number of control qubits

  • aux (int, default: 0 ) –

    only works when 'half_dirty_aux' is chosen, the number of auxiliary qubits

Returns:

Source code in QuICT/core/gate/multicontrol_toffoli.py 
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def __call__(self, control, aux=0) -> CompositeGate:
    """
    By default, the qubit arrangement would be control qubits, target qubit, auxiliary qubits (if exists)

    Args:
        control (int): the number of control qubits
        aux (int, optional): only works when 'half_dirty_aux' is chosen, the number of auxiliary qubits

    Returns:
        CompositeGate: the mct gates
    """
    # Special cases, no MCT would be executed.
    if control == 0:
        gates = CompositeGate()
        X | gates(0)
        return gates
    if control == 1:
        gates = CompositeGate()
        CX | gates([0, 1])
        return gates
    if control == 2:
        gates = CompositeGate()
        CCX | gates([0, 1, 2])
        return gates

    # Otherwise
    if self.aux_usage == 'no_aux':
        return MCTWithoutAux().execute(control + 1)
    elif self.aux_usage == 'one_clean_aux':
        return MCTOneAux().execute(control + 2)
    elif self.aux_usage == 'one_dirty_aux':
        return MCTLinearOneDirtyAux().execute(control + 2)
    else:
        qubit = control + aux + 1
        if control > (qubit // 2) + (1 if qubit % 2 == 1 else 0):
            raise ValueError("MultiControlToffoli.control", f"<= ceil({qubit}/2)", control)
        controls = [i for i in range(control)]
        auxs = [i for i in range(control + 1, qubit)]
        return MCTLinearHalfDirtyAux.assign_qubits(qubit, control, controls, auxs, control)