def state_vector_has_stabilizer(state_vector: np.ndarray, stabilizer: DensePauliString) -> bool:
"""Checks that the state_vector is stabilized by the given stabilizer.
The stabilizer should not modify the value of the state_vector, up to the
global phase.
Args:
state_vector: An input state vector. Is not mutated by this function.
stabilizer: A potential stabilizer of the above state_vector as a
DensePauliString.
Returns:
Whether the stabilizer stabilizes the supplied state.
"""
qubits = LineQubit.range(protocols.num_qubits(stabilizer))
args = act_on_state_vector_args.ActOnStateVectorArgs(
target_tensor=state_vector.copy(),
available_buffer=np.empty_like(state_vector),
qubits=qubits,
prng=np.random.RandomState(),
log_of_measurement_results={},
)
protocols.act_on(stabilizer, args, qubits)
return np.allclose(args.target_tensor, state_vector)
def assert_act_on_clifford_tableau_effect_matches_unitary(val: Any) -> None:
"""Checks that act_on with CliffordTableau generates stabilizers that
stabilize the final state vector. Does not work with Operations or Gates
expecting non-qubit Qids."""
# pylint: disable=unused-variable
__tracebackhide__ = True
# pylint: enable=unused-variable
num_qubits_val = protocols.num_qubits(val)
if not protocols.has_unitary(val) or \
protocols.qid_shape(val) != (2,) * num_qubits_val:
return None
qubits = LineQubit.range(protocols.num_qubits(val) * 2)
qubit_map = {qubit: i for i, qubit in enumerate(qubits)}
circuit = Circuit()
for i in range(num_qubits_val):
circuit.append([
common_gates.H(qubits[i]),
common_gates.CNOT(qubits[i], qubits[-i - 1])
])
if hasattr(val, "on"):
circuit.append(val.on(*qubits[:num_qubits_val]))
else:
circuit.append(val.with_qubits(*qubits[:num_qubits_val]))
tableau = _final_clifford_tableau(circuit, qubit_map)
if tableau is None:
return None
state_vector = np.reshape(final_state_vector(circuit, qubit_order=qubits),
protocols.qid_shape(qubits))
assert all(
state_vector_has_stabilizer(state_vector, stab)
for stab in tableau.stabilizers()), (
"act_on clifford tableau is not consistent with "
"final_state_vector simulation.\n\nval: {!r}".format(val))
def assert_all_implemented_act_on_effects_match_unitary(
val: Any,
assert_tableau_implemented: bool = False,
assert_ch_form_implemented: bool = False) -> None:
"""Uses val's effect on final_state_vector to check act_on(val)'s behavior.
Checks that act_on with CliffordTableau or StabilizerStateCHForm behaves
consistently with act_on through final state vector. Does not work with
Operations or Gates expecting non-qubit Qids. If either of the
assert_*_implmented args is true, fails if the corresponding method is not
implemented for the test circuit.
Args:
val: A gate or operation that may be an input to protocols.act_on.
assert_tableau_implemented: asserts that protocols.act_on() works with
val and ActOnCliffordTableauArgs inputs.
assert_ch_form_implemented: asserts that protocols.act_on() works with
val and ActOnStabilizerStateChFormArgs inputs.
"""
# pylint: disable=unused-variable
__tracebackhide__ = True
# pylint: enable=unused-variable
num_qubits_val = protocols.num_qubits(val)
if (protocols.is_parameterized(val) or not protocols.has_unitary(val)
or protocols.qid_shape(val) != (2, ) * num_qubits_val):
if assert_tableau_implemented or assert_ch_form_implemented:
assert False, ("Could not assert if any act_on methods were "
"implemented. Operating on qudits or with a "
"non-unitary or parameterized operation is "
"unsupported.\n\nval: {!r}".format(val))
return None
qubits = LineQubit.range(protocols.num_qubits(val) * 2)
qubit_map = {qubit: i for i, qubit in enumerate(qubits)}
circuit = Circuit()
for i in range(num_qubits_val):
circuit.append([
common_gates.H(qubits[i]),
common_gates.CNOT(qubits[i], qubits[-i - 1])
])
if hasattr(val, "on"):
circuit.append(val.on(*qubits[:num_qubits_val]))
else:
circuit.append(val.with_qubits(*qubits[:num_qubits_val]))
state_vector = np.reshape(final_state_vector(circuit, qubit_order=qubits),
protocols.qid_shape(qubits))
tableau = _final_clifford_tableau(circuit, qubit_map)
if tableau is None:
assert (
not assert_tableau_implemented
), "Failed to generate final tableau for the test circuit.\n\nval: {!r}".format(
val)
else:
assert all(
state_vector_has_stabilizer(state_vector, stab)
for stab in tableau.stabilizers()), (
"act_on clifford tableau is not consistent with "
"final_state_vector simulation.\n\nval: {!r}".format(val))
stabilizer_ch_form = _final_stabilizer_state_ch_form(circuit, qubit_map)
if stabilizer_ch_form is None:
assert not assert_ch_form_implemented, ("Failed to generate final "
"stabilizer state CH form "
"for the test circuit."
"\n\nval: {!r}".format(val))
else:
np.testing.assert_allclose(
np.reshape(stabilizer_ch_form.state_vector(),
protocols.qid_shape(qubits)),
state_vector,
atol=1e-07,
err_msg=
f"stabilizer_ch_form.state_vector disagrees with state_vector for {val!r}",
verbose=True,
)