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

@property
def is_q_creator(self):

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