def width_def(backend):
    """
    Function to extract the width of a CNOT pulse

    Parameters
    ----------
    backend : qiskit backend
        DESCRIPTION.

    Returns
    -------
    width : int
        samples of the duration of the pulse, in terms of time it will be 
        multiplied by 0.22ns.

    """
    cx_def = backend.defaults().instruction_schedule_map.get("cx",[0,1])
    for inst in cx_def.instructions:
        if (inst[1].duration > 0) and ("CR" in inst[1].name):
            width = inst[1].pulse.width
            return width