'Can we destroy a quasi-particle?  (annihilate hole or annihilate particle)
If so, would that be above or below the fermi surface?
>>> from sympy import Symbol
>>> from sympy.physics.secondquant import Fd
>>> a = Symbol(\'a\', above_fermi=1)
>>> i = Symbol(\'i\', below_fermi=1)
>>> p = Symbol(\'p\')
>>> Fd(a).is_q_annihilator
0
>>> Fd(i).is_q_annihilator
-1
>>> Fd(p).is_q_annihilator
-1'

@property
def is_q_annihilator(self):

    if self.is_below_fermi:
        return (-1)
    return 0
