def _with_parameterized_layers(circuit: 'cirq.AbstractCircuit',
qubits: Sequence['cirq.Qid'],
needs_init_layer: bool) -> 'cirq.Circuit':
"""Return a copy of the input circuit with parameterized single-qubit rotations.
These rotations flank the circuit: the initial two layers of X and Y gates
are given parameter names "{qubit}-Xi" and "{qubit}-Yi" and are used
to set up the initial state. If `needs_init_layer` is False,
these two layers of gates are omitted.
The final two layers of X and Y gates are given parameter names
"{qubit}-Xf" and "{qubit}-Yf" and are use to change the frame of the
qubit before measurement, effectively measuring in bases other than Z.
"""
x_beg_mom = circuits.Moment(
[ops.X(q)**sympy.Symbol(f'{q}-Xi') for q in qubits])
y_beg_mom = circuits.Moment(
[ops.Y(q)**sympy.Symbol(f'{q}-Yi') for q in qubits])
x_end_mom = circuits.Moment(
[ops.X(q)**sympy.Symbol(f'{q}-Xf') for q in qubits])
y_end_mom = circuits.Moment(
[ops.Y(q)**sympy.Symbol(f'{q}-Yf') for q in qubits])
meas_mom = circuits.Moment([ops.measure(*qubits, key='z')])
if needs_init_layer:
total_circuit = circuits.Circuit([x_beg_mom, y_beg_mom])
total_circuit += circuit.unfreeze()
else:
total_circuit = circuit.unfreeze()
total_circuit.append([x_end_mom, y_end_mom, meas_mom])
return total_circuit
def split_into_matching_protocol_then_general(
circuit: 'cirq.AbstractCircuit', predicate: Callable[['cirq.Operation'],
bool]
) -> Tuple['cirq.AbstractCircuit', 'cirq.AbstractCircuit']:
"""Splits the circuit into a matching prefix and non-matching suffix.
The splitting happens in a per-qubit fashion. A non-matching operation on
qubit A will cause later operations on A to be part of the non-matching
suffix, but later operations on other qubits will continue to be put into
the matching part (as long as those qubits have had no non-matching operation
up to that point).
"""
blocked_qubits: Set[cirq.Qid] = set()
matching_prefix = circuits.Circuit()
general_suffix = circuits.Circuit()
for moment in circuit:
matching_part = []
general_part = []
for op in moment:
qs = set(op.qubits)
if not predicate(op) or not qs.isdisjoint(blocked_qubits):
blocked_qubits |= qs
if qs.isdisjoint(blocked_qubits):
matching_part.append(op)
else:
general_part.append(op)
if matching_part:
matching_prefix.append(circuits.Moment(matching_part))
if general_part:
general_suffix.append(circuits.Moment(general_part))
return matching_prefix, general_suffix
def test_depolarizer_different_gate():
q1 = ops.QubitId()
q2 = ops.QubitId()
cnot = Job(circuits.Circuit([
circuits.Moment([ops.CNOT(q1, q2)]),
]))
allerrors = DepolarizerChannel(
probability=1.0,
depolarizing_gates=[xmon_gates.ExpZGate(),
xmon_gates.ExpWGate()])
p0 = Symbol(DepolarizerChannel._parameter_name + '0')
p1 = Symbol(DepolarizerChannel._parameter_name + '1')
p2 = Symbol(DepolarizerChannel._parameter_name + '2')
p3 = Symbol(DepolarizerChannel._parameter_name + '3')
error_sweep = (Points(p0.name, [1.0]) + Points(p1.name, [1.0]) +
Points(p2.name, [1.0]) + Points(p3.name, [1.0]))
cnot_then_z = Job(
circuits.Circuit([
circuits.Moment([ops.CNOT(q1, q2)]),
circuits.Moment([
xmon_gates.ExpZGate(half_turns=p0).on(q1),
xmon_gates.ExpZGate(half_turns=p1).on(q2)
]),
circuits.Moment([
xmon_gates.ExpWGate(half_turns=p2).on(q1),
xmon_gates.ExpWGate(half_turns=p3).on(q2)
])
]), cnot.sweep * error_sweep)
assert allerrors.transform_job(cnot) == cnot_then_z
def test_leaves_singleton():
m = MergeRotations(0.000001)
q = ops.QubitId()
c = circuits.Circuit([circuits.Moment([ops.X(q)])])
m.optimization_at(c, 0, c.operation_at(q, 0))
assert c == circuits.Circuit([circuits.Moment([ops.X(q)])])
def test_clears_paired_cnot():
q0 = ops.QubitId()
q1 = ops.QubitId()
assert_optimizes(
before=circuits.Circuit([
circuits.Moment([ops.CNOT(q0, q1)]),
circuits.Moment([ops.CNOT(q0, q1)]),
]),
after=circuits.Circuit())
def test_removes_identity_sequence():
q = ops.QubitId()
assert_optimizes(before=circuits.Circuit([
circuits.Moment([ops.Z(q)]),
circuits.Moment([ops.H(q)]),
circuits.Moment([ops.X(q)]),
circuits.Moment([ops.H(q)]),
]),
after=circuits.Circuit())
def test_ignores_2qubit_target():
m = MergeRotations(0.000001)
q = ops.QubitId()
q2 = ops.QubitId()
c = circuits.Circuit([
circuits.Moment([ops.CZ(q, q2)]),
])
m.optimization_at(c, 0, c.operation_at(q, 0))
assert c == circuits.Circuit([circuits.Moment([ops.CZ(q, q2)])])
def noisy_moment(self, moment: 'cirq.Moment',
system_qubits: Sequence['cirq.Qid']):
if validate_all_measurements(moment):
return [
circuits.Moment(
self.readout_noise_gate(q) for q in system_qubits), moment
]
return [
moment,
circuits.Moment(self.qubit_noise_gate(q) for q in system_qubits)
]
def _circuit_plus_pauli_string_measurements(
circuit: 'cirq.Circuit',
pauli_string: 'cirq.PauliString') -> 'cirq.Circuit':
"""A circuit measuring the given observable at the end of the given circuit."""
assert pauli_string
circuit = circuit.copy()
circuit.append(circuits.Moment(pauli_string.to_z_basis_ops()))
circuit.append(
circuits.Moment([ops.measure(*sorted(pauli_string.keys()),
key='out')]))
return circuit
def test_drop():
q1 = ops.QubitId()
q2 = ops.QubitId()
assert_optimizes(before=circuits.Circuit([
circuits.Moment(),
circuits.Moment(),
circuits.Moment([ops.CNOT(q1, q2)]),
circuits.Moment(),
]),
after=circuits.Circuit([
circuits.Moment([ops.CNOT(q1, q2)]),
]))
def test_clears_small():
m = circuits.DropNegligible(0.001)
q = ops.QubitId()
c = circuits.Circuit([circuits.Moment([ops.Z(q)**0.000001])])
assert (m.optimization_at(c, 0, c.operation_at(q, 0)) ==
circuits.PointOptimizationSummary(clear_span=1,
clear_qubits=[q],
new_operations=[]))
m.optimize_circuit(c)
assert c == circuits.Circuit([circuits.Moment()])
def test_combines_sequence():
m = MergeRotations(0.000001)
q = ops.QubitId()
c = circuits.Circuit([
circuits.Moment([ops.X(q)**0.5]),
circuits.Moment([ops.Z(q)**0.5]),
circuits.Moment([ops.X(q)**-0.5]),
])
assert (m.optimization_at(c, 0, c.operation_at(
q,
0)) == circuits.PointOptimizationSummary(clear_span=3,
clear_qubits=[q],
new_operations=ops.Y(q)**0.5))
def align_left(
circuit: 'cirq.AbstractCircuit',
*,
context: Optional['cirq.TransformerContext'] = None) -> 'cirq.Circuit':
"""Align gates to the left of the circuit.
Note that tagged operations with tag in `context.tags_to_ignore` will continue to stay in their
original position and will not be aligned.
Args:
circuit: Input circuit to transform.
context: `cirq.TransformerContext` storing common configurable options for transformers.
Returns:
Copy of the transformed input circuit.
"""
if context is None:
context = transformer_api.TransformerContext()
ret = circuits.Circuit()
for i, moment in enumerate(circuit):
for op in moment:
if isinstance(op, ops.TaggedOperation) and set(
op.tags).intersection(context.tags_to_ignore):
ret.append([circuits.Moment()] * (i + 1 - len(ret)))
ret[i] = ret[i].with_operation(op)
else:
ret.append(op)
return ret
def _init_ops(data: Dict[str, Any]) -> 'cirq.OP_TREE':
if 'init' not in data:
return []
init = data['init']
if not isinstance(init, List):
raise ValueError(f'Circuit JSON init must be a list but was {init!r}.')
init_ops = []
for i in range(len(init)):
state = init[i]
q = devices.LineQubit(i)
if state == 0:
pass
elif state == 1:
init_ops.append(ops.X(q))
elif state == '+':
init_ops.append(ops.ry(np.pi / 2).on(q))
elif state == '-':
init_ops.append(ops.ry(-np.pi / 2).on(q))
elif state == 'i':
init_ops.append(ops.rx(-np.pi / 2).on(q))
elif state == '-i':
init_ops.append(ops.rx(np.pi / 2).on(q))
else:
raise ValueError(f'Unrecognized init state: {state!r}')
return circuits.Moment(init_ops)
def rectify_acquaintance_strategy(circuit: circuits.Circuit,
acquaint_first: bool = True) -> None:
"""Splits moments so that they contain either only acquaintance gates
or only permutation gates. Orders resulting moments so that the first one
is of the same type as the previous one.
Args:
circuit: The acquaintance strategy to rectify.
acquaint_first: Whether to make acquaintance moment first in when
splitting the first mixed moment.
"""
if not is_acquaintance_strategy(circuit):
raise TypeError('not is_acquaintance_strategy(circuit)')
rectified_moments = []
for moment in circuit:
gate_type_to_ops = collections.defaultdict(
list) # type: Dict[bool, List[ops.GateOperation]]
for op in moment.operations:
gate_type_to_ops[isinstance(
op.gate, AcquaintanceOpportunityGate)].append(op)
if len(gate_type_to_ops) == 1:
rectified_moments.append(moment)
continue
for acquaint_first in sorted(gate_type_to_ops.keys(),
reverse=acquaint_first):
rectified_moments.append(
circuits.Moment(gate_type_to_ops[acquaint_first]))
circuit._moments = rectified_moments
def display_mapping(circuit: 'cirq.Circuit', initial_mapping: LogicalMapping) -> None:
"""Inserts display gates between moments to indicate the mapping throughout
the circuit."""
qubits = sorted(circuit.all_qubits())
mapping = initial_mapping.copy()
old_moments = circuit._moments
gate = MappingDisplayGate(mapping.get(q) for q in qubits)
new_moments = [circuits.Moment([gate(*qubits)])]
for moment in old_moments:
new_moments.append(moment)
update_mapping(mapping, moment)
gate = MappingDisplayGate(mapping.get(q) for q in qubits)
new_moments.append(circuits.Moment([gate(*qubits)]))
circuit._moments = new_moments
def get_grid_interaction_layer_circuit(
device_graph: nx.Graph,
pattern: Sequence[GridInteractionLayer] = HALF_GRID_STAGGERED_PATTERN,
two_qubit_gate=ops.ISWAP**0.5,
) -> 'cirq.Circuit':
"""Create a circuit representation of a grid interaction pattern on a given device topology.
The resulting circuit is deterministic, of depth len(pattern), and consists of `two_qubit_gate`
applied to each pair in `pattern` restricted to available connections in `device_graph`.
Args:
device_graph: A graph whose nodes are qubits and whose edges represent the possibility of
doing a two-qubit gate. This combined with the `pattern` argument determines which
two qubit pairs are activated when.
pattern: A sequence of `GridInteractionLayer`, each of which has a particular set of
qubits that are activated simultaneously. These pairs of qubits are deduced by
combining this argument with `device_graph`.
two_qubit_gate: The two qubit gate to use in constructing the circuit layers.
"""
moments = []
for layer in pattern:
pairs = sorted(_get_active_pairs(device_graph, layer))
if len(pairs) == 0:
continue
moments += [
circuits.Moment(two_qubit_gate.on(*pair) for pair in pairs)
]
return circuits.Circuit(moments)
def remove_redundant_acquaintance_opportunities(
strategy: 'cirq.Circuit') -> int:
"""Removes redundant acquaintance opportunities."""
qubits = sorted(strategy.all_qubits())
mapping = {q: i for i, q in enumerate(qubits)}
expose_acquaintance_gates(strategy)
annotated_strategy = strategy.copy()
LogicalAnnotator(mapping)(annotated_strategy)
new_moments: List['cirq.Moment'] = []
acquaintance_opps: Set[FrozenSet[int]] = set()
n_removed = 0
for moment in annotated_strategy:
new_moment: List['cirq.Operation'] = []
for op in moment:
if isinstance(op, AcquaintanceOperation):
opp = frozenset(cast(Sequence[int], op.logical_indices))
if opp not in acquaintance_opps:
acquaintance_opps.add(opp)
new_moment.append(acquaint(*op.qubits))
else:
n_removed += 1
else:
new_moment.append(op)
new_moments.append(circuits.Moment(new_moment))
strategy._moments = new_moments
return n_removed
def build_entangling_layers(qubits: Sequence[devices.GridQubit],
two_qubit_gate: ops.Gate) -> List[circuits.Moment]:
"""Builds a sequence of gates that entangle all pairs of qubits on a grid.
The qubits are restricted to be physically on a square grid with distinct
row and column indices (not every node of the grid needs to have a
qubit). To entangle all pairs of qubits, a user-specified two-qubit gate
is applied between each and every pair of qubit that are next to each
other. In general, a total of four sets of parallel operations are needed to
perform all possible two-qubit gates. We proceed as follows:
The first layer applies two-qubit gates to qubits (i, j) and (i, j + 1)
where i is any integer and j is an even integer. The second layer
applies two-qubit gates to qubits (i, j) and (i + 1, j) where i is an even
integer and j is any integer. The third layer applies two-qubit gates
to qubits (i, j) and (i, j + 1) where i is any integer and j is an odd
integer. The fourth layer applies two-qubit gates to qubits (i, j) and
(i + 1, j) where i is an odd integer and j is any integer.
After the layers are built as above, any empty layer is ejected.:
Cycle 1: Cycle 2:
q00 ── q01 q02 ── q03 q00 q01 q02 q03
| | | |
q10 ── q11 q12 ── q13 q10 q11 q12 q13
q20 ── q21 q22 ── q23 q20 q21 q22 q23
| | | |
q30 ── q31 q32 ── q33 q30 q31 q32 q33
Cycle 3: Cycle 4:
q00 q01 ── q02 q03 q00 q01 q02 q03
q10 q11 ── q12 q13 q10 q11 q12 q13
| | | |
q20 q21 ── q22 q23 q20 q21 q22 q23
q30 q31 ── q32 q33 q30 q31 q32 q33
Args:
qubits: The grid qubits included in the entangling operations.
two_qubit_gate: The two-qubit gate to be applied between all
neighboring pairs of qubits.
Returns:
A list of circuits.Moment, with a maximum length of 4. Each circuits.Moment
includes two-qubit gates which can be performed at the same time.
Raises:
ValueError: two-qubit gate is not used.
"""
if protocols.num_qubits(two_qubit_gate) != 2:
raise ValueError('Input must be a two-qubit gate')
interaction_sequence = _default_interaction_sequence(qubits)
return [
circuits.Moment([two_qubit_gate(q_a, q_b) for (q_a, q_b) in pairs])
for pairs in interaction_sequence
]
def map_operations(
circuit: CIRCUIT_TYPE,
map_func: Callable[[ops.Operation, int], ops.OP_TREE],
*,
deep: bool = False,
raise_if_add_qubits=True,
tags_to_ignore: Sequence[Hashable] = (),
) -> CIRCUIT_TYPE:
"""Applies local transformations on operations, by calling `map_func(op)` for each op.
By default, the function assumes `issubset(qubit_set(map_func(op)), op.qubits)` is True.
Args:
circuit: Input circuit to apply the transformations on. The input circuit is not mutated.
map_func: Mapping function from (cirq.Operation, moment_index) to a cirq.OP_TREE. If the
resulting optree spans more than 1 moment, it's inserted in-place in the same moment as
`cirq.CircuitOperation(cirq.FrozenCircuit(op_tree)).with_tags(MAPPED_CIRCUIT_OP_TAG)`
to preserve moment structure. Utility methods like `cirq.unroll_circuit_op` can
subsequently be used to unroll the mapped circuit operation.
deep: If true, `map_func` will be recursively applied to circuits wrapped inside
any circuit operations contained within `circuit`.
raise_if_add_qubits: Set to True by default. If True, raises ValueError if `map_func(op)`
adds operations on qubits outside of `op.qubits`.
tags_to_ignore: Sequence of tags which should be ignored while applying `map_func` on
tagged operations -- i.e. `map_func(op, idx)` will be called only for operations that
satisfy `set(op.tags).isdisjoint(tags_to_ignore)`.
Raises:
ValueError if `issubset(qubit_set(map_func(op)), op.qubits) is False` and
`raise_if_add_qubits is True`.
Returns:
Copy of input circuit with mapped operations (wrapped in a tagged CircuitOperation).
"""
def apply_map(op: ops.Operation, idx: int) -> ops.OP_TREE:
if not set(op.tags).isdisjoint(tags_to_ignore):
return op
c = circuits.FrozenCircuit(map_func(op, idx))
if raise_if_add_qubits and not c.all_qubits().issubset(op.qubits):
raise ValueError(
f"Mapped operations {c.all_operations()} should act on a subset "
f"of qubits of the original operation {op}")
if len(c) <= 1:
# Either empty circuit or all operations act in the same moment;
# So, we don't need to wrap them in a circuit_op.
return c[0].operations if c else []
circuit_op = circuits.CircuitOperation(c).with_tags(
MAPPED_CIRCUIT_OP_TAG)
return circuit_op
return map_moments(
circuit,
lambda m, i:
[circuits.Moment(apply_map(op, i) for op in m.operations)],
deep=deep,
tags_to_ignore=tags_to_ignore,
)
def test_extension():
class DummyGate(ops.Gate):
pass
optimizer = MergeRotations(extensions=Extensions({
ops.KnownMatrixGate: {
DummyGate:
lambda _: ops.SingleQubitMatrixGate(np.array([[0, 1], [1, 0]]))
}
}))
q = ops.QubitId()
c = circuits.Circuit([
circuits.Moment([DummyGate().on(q)]),
])
assert_optimizes(before=c,
after=circuits.Circuit([circuits.Moment([ops.X(q)])]),
optimizer=optimizer)
def test_depolarizer_no_errors():
q1 = ops.QubitId()
q2 = ops.QubitId()
cnot = Job(circuits.Circuit([
circuits.Moment([ops.CNOT(q1, q2)]),
]))
noerrors = DepolarizerChannel(probability=0.0)
assert noerrors.transform_job(cnot) == cnot
def test_leaves_big():
m = circuits.DropNegligible(0.001)
q = ops.QubitId()
c = circuits.Circuit([circuits.Moment([ops.Z(q)**0.1])])
assert m.optimization_at(c, 0, c.operation_at(q, 0)) is None
d = circuits.Circuit(c.moments)
m.optimize_circuit(d)
assert d == c
def merge_func(m1: 'cirq.Moment', m2: 'cirq.Moment') -> Optional['cirq.Moment']:
if not (can_merge_moment(m1) and can_merge_moment(m2)):
return None
ret_ops = []
for q in m1.qubits | m2.qubits:
mat = protocols.unitary(circuits.Circuit(m.operation_at(q) or [] for m in [m1, m2]))
gate = single_qubit_decompositions.single_qubit_matrix_to_phxz(mat, atol)
if gate:
ret_ops.append(gate(q))
return circuits.Moment(ret_ops)
def cubic_acquaintance_strategy(
qubits: Iterable['cirq.Qid'], swap_gate: 'cirq.Gate' = ops.SWAP
) -> 'cirq.Circuit':
"""Acquaints every triple of qubits.
Exploits the fact that in a simple linear swap network every pair of
logical qubits that starts at distance two remains so (except temporarily
near the edge), and that every third one `goes through` the pair at some
point in the network. The strategy then iterates through a series of
mappings in which qubits i and i + k are placed at distance two, for k = 1
through n / 2. Linear swap networks are used in between to effect the
permutation.
"""
qubits = tuple(qubits)
n_qubits = len(qubits)
swap_gate = SwapPermutationGate(swap_gate)
moments = []
index_order = tuple(range(n_qubits))
max_separation = max(((n_qubits - 1) // 2) + 1, 2)
for separation in range(1, max_separation):
stepped_indices_concatenated = tuple(
itertools.chain(*(range(offset, n_qubits, separation) for offset in range(separation)))
)
new_index_order = skip_and_wrap_around(stepped_indices_concatenated)
permutation = {i: new_index_order.index(j) for i, j in enumerate(index_order)}
permutation_gate = LinearPermutationGate(n_qubits, permutation, swap_gate)
moments.append(circuits.Moment([permutation_gate(*qubits)]))
for i in range(n_qubits + 1):
for offset in range(3):
moment = circuits.Moment(
acquaint(*qubits[j : j + 3]) for j in range(offset, n_qubits - 2, 3)
)
moments.append(moment)
if i < n_qubits:
moment = circuits.Moment(
swap_gate(*qubits[j : j + 2]) for j in range(i % 2, n_qubits - 1, 2)
)
moments.append(moment)
index_order = new_index_order[::-1]
return circuits.Circuit(moments)
def new_layer(self, previous_single_qubit_layer: 'cirq.Moment') -> 'cirq.Moment':
def random_gate(qubit: 'cirq.Qid') -> 'cirq.Gate':
excluded_op = previous_single_qubit_layer.operation_at(qubit)
excluded_gate = excluded_op.gate if excluded_op is not None else None
g = self.single_qubit_gates[self.prng.randint(0, len(self.single_qubit_gates))]
while g is excluded_gate:
g = self.single_qubit_gates[self.prng.randint(0, len(self.single_qubit_gates))]
return g
return circuits.Moment(random_gate(q).on(q) for q in self.qubits)
def map_func(m: 'cirq.Moment', _) -> Sequence['cirq.Moment']:
stratified_ops: List[List['cirq.Operation']] = [[] for _ in range(num_categories)]
for op in m:
if set(op.tags) & set(context.tags_to_ignore):
stratified_ops[0].append(op)
continue
for i, classifier in enumerate(classifiers):
if classifier(op):
stratified_ops[i + 1].append(op)
break
return [circuits.Moment(op_list) for op_list in stratified_ops]
def parameterize_circuit(
circuit: 'cirq.Circuit',
options: XEBCharacterizationOptions) -> 'cirq.Circuit':
"""Parameterize PhasedFSim-like gates in a given circuit according to
`phased_fsim_options`.
"""
gate = options.get_parameterized_gate()
return circuits.Circuit(
circuits.Moment(
gate.on(*op.qubits) if options.should_parameterize(op) else op
for op in moment.operations) for moment in circuit.moments)
def test_clears_known_empties_even_at_zero_tolerance():
m = circuits.DropNegligible(0.001)
q = ops.QubitId()
q2 = ops.QubitId()
c = circuits.Circuit.from_ops(
ops.Z(q)**0,
ops.Y(q)**0.0000001,
ops.X(q)**-0.0000001,
ops.CZ(q, q2)**0)
m.optimize_circuit(c)
assert c == circuits.Circuit([circuits.Moment()] * 4)
def noisy_moment(self, moment: 'cirq.Moment',
system_qubits: Sequence['cirq.Qid']):
if self.is_virtual_moment(moment):
return moment
if validate_all_measurements(moment):
return [
circuits.Moment(
self.readout_noise_gate(q).with_tags(ops.VirtualTag())
for q in system_qubits),
moment,
]
return moment
