def _operator_generator(index, conj):
"""
Internal method to generate the appropriate operator
"""
pterm = PauliTerm('I', 0, 1.0)
Zstring = PauliTerm('I', 0, 1.0)
for j in range(index):
Zstring = Zstring * PauliTerm('Z', j, 1.0)
pterm1 = Zstring * PauliTerm('X', index, 0.5)
scalar = 0.5 * conj * 1.0j
pterm2 = Zstring * PauliTerm('Y', index, scalar)
pterm = pterm * (pterm1 + pterm2)
pterm = pterm.simplify()
return pterm
def product_ops(self, indices, conjugate):
"""
Convert a list of site indices and coefficients to a Pauli Operators
list with the generalized Bravyi-Kitaev transformation.
:param list indices: list of ints specifying the site the fermionic
operator acts on, e.g. [0,2,4,6]
:param list conjugate: List of -1, 1 specifying which of the indices
are creation operators (-1) and which are
annihilation operators (1). e.g. [-1,-1,1,1]
"""
pterm = PauliTerm('I', 0, 1.0)
for conj, index in zip(conjugate, indices):
pterm = pterm * self._operator_generator(index, conj)
pterm = pterm.simplify()
return pterm
def test_zero_terms():
term = PauliTerm("X", 0, 1.0) + PauliTerm("X", 0, -1.0) + PauliTerm("Y", 0, 0.5)
assert str(term) == "(0.5+0j)*Y0"
term = PauliTerm("X", 0, 1.0) + PauliTerm("X", 0, -1.0)
assert str(term) == "0j*I"
assert len(term.terms) == 1
term2 = term * PauliTerm("Z", 2, 0.5)
assert str(term2) == "0j*I"
term3 = PauliTerm("Z", 2, 0.5) + term
assert str(term3) == "(0.5+0j)*Z2"
term4 = PauliSum([])
assert str(term4) == "0j*I"
term = PauliSum([PauliTerm("X", 0, 0.0), PauliTerm("Y", 1, 1.0) * PauliTerm("Z", 2)])
assert str(term) == "0j*X0 + (1+0j)*Y1*Z2"
term = term.simplify()
assert str(term) == "(1+0j)*Y1*Z2"
