def test_special_operators():
# sigma+ sigma- as well as Q+ and Q-
assert (paulis.Sp(0) * paulis.Sp(0) == QubitHamiltonian.zero())
assert (paulis.Sm(0) * paulis.Sm(0) == QubitHamiltonian.zero())
assert (paulis.Qp(0) * paulis.Qp(0) == paulis.Qp(0))
assert (paulis.Qm(0) * paulis.Qm(0) == paulis.Qm(0))
assert (paulis.Qp(0) * paulis.Qm(0) == QubitHamiltonian.zero())
assert (paulis.Qm(0) * paulis.Qp(0) == QubitHamiltonian.zero())
assert (paulis.Sp(0) * paulis.Sm(0) == paulis.Qp(0))
assert (paulis.Sm(0) * paulis.Sp(0) == paulis.Qm(0))
assert (paulis.Sp(0) + paulis.Sm(0) == paulis.X(0))
assert (paulis.Qp(0) + paulis.Qm(0) == paulis.I(0))
def test_simple_arithmetic():
qubit = random.randint(0, 5)
primitives = [paulis.X, paulis.Y, paulis.Z]
assert (paulis.X(qubit).conjugate() == paulis.X(qubit))
assert (paulis.Y(qubit).conjugate() == -1 * paulis.Y(qubit))
assert (paulis.Z(qubit).conjugate() == paulis.Z(qubit))
assert (paulis.X(qubit).transpose() == paulis.X(qubit))
assert (paulis.Y(qubit).transpose() == -1 * paulis.Y(qubit))
assert (paulis.Z(qubit).transpose() == paulis.Z(qubit))
for P in primitives:
assert (P(qubit) * P(qubit) == QubitHamiltonian(1.0))
n = random.randint(0, 10)
nP = QubitHamiltonian.zero()
for i in range(n):
nP += P(qubit)
assert (n * P(qubit) == nP)
for i, Pi in enumerate(primitives):
i1 = (i + 1) % 3
i2 = (i + 2) % 3
assert (Pi(qubit) * primitives[i1](qubit) == 1j *
primitives[i2](qubit))
assert (primitives[i1](qubit) * Pi(qubit) == -1j *
primitives[i2](qubit))
for qubit2 in random.randint(6, 10, 5):
if qubit2 == qubit: continue
P = primitives[random.randint(0, 2)]
assert (Pi(qubit) * primitives[i1](qubit) * P(qubit2) == 1j *
primitives[i2](qubit) * P(qubit2))
assert (P(qubit2) * primitives[i1](qubit) * Pi(qubit) == -1j *
P(qubit2) * primitives[i2](qubit))
def Zero(*args, **kwargs) -> QubitHamiltonian:
"""
Initialize 0 Operator
Returns
-------
QubitHamiltonian
"""
return QubitHamiltonian.zero()
def KetBra(ket: QubitWaveFunction,
bra: QubitWaveFunction,
hermitian: bool = False,
threshold: float = 1.e-6,
n_qubits=None):
"""
Notes
----------
Initialize the general KetBra operator
.. math::
H = \\lvert ket \\rangle \\langle bra \\rvert
e.g.
wfn1 = tq.QubitWaveFunction.from_string("1.0*|00> + 1.0*|11>").normalize()
wfn2 = tq.QubitWaveFunction.from_string("1.0*|00>")
operator = tq.paulis.KetBra(ket=wfn1, bra=wfn1)
initializes the transfer operator from the all-zero state to a Bell state
Parameters
----------
ket: QubitWaveFunction:
QubitWaveFunction which defines the ket element
can also be given as string or array or integer
bra: QubitWaveFunction:
QubitWaveFunction which defines the bra element
can also be given as string or array or integer
hermitian: bool: (Default False)
if True the hermitian version H + H^\dagger is returned
threshold: float: (Default 1.e-6)
elements smaller than the threshold will be ignored
n_qubits: only needed if ket and/or bra are passed down as integers
Returns
-------
a tequila QubitHamiltonian (not necessarily hermitian)
"""
H = QubitHamiltonian.zero()
ket = QubitWaveFunction(state=ket, n_qubits=n_qubits)
bra = QubitWaveFunction(state=bra, n_qubits=n_qubits)
for k1, v1 in bra.items():
for k2, v2 in ket.items():
c = v1.conjugate() * v2
if not numpy.isclose(c, 0.0, atol=threshold):
H += c * decompose_transfer_operator(bra=k1, ket=k2)
if hermitian:
return H.split()[0]
else:
return H.simplify(threshold=threshold)
def Projector(wfn, threshold=0.0, n_qubits=None) -> QubitHamiltonian:
"""
Notes
----------
Initialize a projector given by
.. math::
H = \\lvert \\Psi \\rangle \\langle \\Psi \\rvert
Parameters
----------
wfn: QubitWaveFunction or int, or string, or array :
The wavefunction onto which the projector projects
Needs to be passed down as tequilas QubitWaveFunction type
See the documentation on how to initialize a QubitWaveFunction from
integer, string or array (can also be passed down diretly as one of those types)
threshold: float: (Default value = 0.0)
neglect small parts of the operator
n_qubits: only needed when an integer is given as wavefunction
Returns
-------
"""
wfn = QubitWaveFunction(state=wfn, n_qubits=n_qubits)
H = QubitHamiltonian.zero()
for k1, v1 in wfn.items():
for k2, v2 in wfn.items():
c = v1.conjugate() * v2
if not numpy.isclose(c, 0.0, atol=threshold):
H += c * decompose_transfer_operator(bra=k1, ket=k2)
assert (H.is_hermitian())
return H
