def _compile_layered(self, target_unitary: Unitary,
unitary_primitive_counts: Dict[UnitaryPrimitive,
int], threshold: float,
max_step_count: int) -> CompilerResult:
'''
Internal implementation of layered STOQ compilation.
See documentation for Compiler.compile_layered() for full details.
'''
compiled_sequence = UnitarySequence(self.dimension)
cost_by_step = []
while (not compiled_sequence.product().close_to(
target_unitary, threshold)
and len(cost_by_step) < max_step_count):
self.beta = min(self.beta + self.annealing_rate, self.max_beta)
product_before_change = compiled_sequence.product()
self._make_random_change_layered(compiled_sequence,
unitary_primitive_counts)
current_cost = target_unitary.distance_from(product_before_change)
proposed_cost = target_unitary.distance_from(
compiled_sequence.product())
accept = self._accept_proposed_change(target_unitary, current_cost,
proposed_cost)
if accept:
cost_by_step.append(proposed_cost)
else:
compiled_sequence.undo()
cost_by_step.append(current_cost)
return compiled_sequence, cost_by_step
def test_undo(self) -> None:
dimension = 2
identity = Unitary.identity(dimension)
sequence = UnitarySequence(dimension)
assert sequence.get_length() == 0
with pytest.raises(Exception):
sequence.undo()
sequence.append_first(
UnitarySequenceEntry(UnitaryDefinitions.sigmax(), [0]))
assert sequence.get_length() == 1
assert sequence.product().close_to(UnitaryDefinitions.sigmax())
sequence.undo()
assert sequence.get_length() == 0
assert sequence.product().close_to(identity)
with pytest.raises(Exception):
sequence.undo()
sequence.append_first(
UnitarySequenceEntry(UnitaryDefinitions.sigmay(), [0]))
sequence.append_first(
UnitarySequenceEntry(UnitaryDefinitions.sigmay(), [0]))
assert sequence.get_length() == 2
assert sequence.product().close_to(identity)
sequence.remove_last()
assert sequence.get_length() == 1
assert sequence.product().close_to(UnitaryDefinitions.sigmay())
sequence.undo()
assert sequence.get_length() == 2
assert sequence.product().close_to(identity)
with pytest.raises(Exception):
sequence.undo()