def test_swap_permutation_gate():
no_decomp = lambda op: (isinstance(op, cirq.GateOperation) and op.gate ==
cirq.SWAP)
a, b = cirq.NamedQubit('a'), cirq.NamedQubit('b')
expander = cirq.ExpandComposite(no_decomp=no_decomp)
circuit = cirq.Circuit.from_ops(SwapPermutationGate()(a, b))
expander(circuit)
assert tuple(circuit.all_operations()) == (cirq.SWAP(a, b), )
no_decomp = lambda op: (isinstance(op, cirq.GateOperation) and op.gate ==
cirq.CZ)
expander = cirq.ExpandComposite(no_decomp=no_decomp)
circuit = cirq.Circuit.from_ops(SwapPermutationGate(cirq.CZ)(a, b))
expander(circuit)
assert tuple(circuit.all_operations()) == (cirq.CZ(a, b), )
def test_update_mapping():
gate = SwapPermutationGate()
a, b, c = (cirq.NamedQubit(s) for s in 'abc')
mapping = {s: i for i, s in enumerate((a, b, c))}
ops = [gate(a, b), gate(b, c)]
update_mapping(mapping, ops)
assert mapping == {a: 1, b: 2, c: 0}
def decompose_matching(self, qubits: Sequence[ops.Qid]) -> ops.OP_TREE:
swap_gate = SwapPermutationGate(self.swap_gate)
for k in range(-self.part_size + 1, self.part_size):
for x in range(abs(k), 2 * self.part_size - abs(k), 2):
if (x + 1) % self.part_size:
yield swap_gate(*qubits[x:x + 2])
else:
yield acquaint(*qubits[x:x + 2])
def test_validate_permutation_errors():
validate_permutation = PermutationGate.validate_permutation
validate_permutation({})
with pytest.raises(IndexError,
message='key and value sets must be the same.'):
validate_permutation({0: 2, 1: 3})
with pytest.raises(
IndexError,
message='keys of the permutation must be non-negative.'):
validate_permutation({-1: 0, 0: -1})
with pytest.raises(IndexError, message='key is out of bounds.'):
validate_permutation({0: 3, 3: 0}, 2)
gate = SwapPermutationGate()
args = cirq.TextDiagramInfoArgs.UNINFORMED_DEFAULT
assert gate.text_diagram_info(args) == NotImplemented
def _decompose_(self, qubits: Sequence[QubitId]) -> OP_TREE:
n = len(qubits)
left_shift = self.shift % n
right_shift = n - left_shift
mins = chain(range(left_shift - 1, 0, -1), range(right_shift))
maxs = chain(range(left_shift, n), range(n - 1, right_shift, -1))
swap_gate = SwapPermutationGate(self.swap_gate)
for i, j in zip(mins, maxs):
for k in range(i, j, 2):
yield swap_gate(*qubits[k:k + 2])
def test_diagram():
gate = SwapPermutationGate()
a, b = cirq.NamedQubit('a'), cirq.NamedQubit('b')
circuit = cirq.Circuit.from_ops([gate(a, b)])
actual_text_diagram = circuit.to_text_diagram()
expected_text_diagram = """
a: ───0↦1───
│
b: ───1↦0───
""".strip()
assert actual_text_diagram == expected_text_diagram
def decompose_complete(self, qubits: Sequence[ops.Qid]) -> ops.OP_TREE:
swap_gate = SwapPermutationGate(self.swap_gate)
if self.part_size == 1:
yield acquaint(*qubits)
return
for k in range(-self.part_size + 1, self.part_size - 1):
for x in range(abs(k), 2 * self.part_size - abs(k), 2):
yield acquaint(*qubits[x:x + 2])
yield swap_gate(*qubits[x:x + 2])
yield acquaint(qubits[self.part_size - 1], qubits[self.part_size])
for k in reversed(range(-self.part_size + 1, self.part_size - 1)):
for x in range(abs(k), 2 * self.part_size - abs(k), 2):
yield acquaint(*qubits[x:x + 2])
yield swap_gate(*qubits[x:x + 2])
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(ops.Moment([permutation_gate(*qubits)]))
for i in range(n_qubits + 1):
for offset in range(3):
moment = ops.Moment(
acquaint(*qubits[j:j + 3])
for j in range(offset, n_qubits - 2, 3))
moments.append(moment)
if i < n_qubits:
moment = ops.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, device=UnconstrainedAcquaintanceDevice)
def test_validate_permutation_errors():
validate_permutation = PermutationGate.validate_permutation
validate_permutation({})
with pytest.raises(IndexError,
message='key and value sets must be the same.'):
validate_permutation({0: 2, 1: 3})
with pytest.raises(IndexError,
message='keys of the permutation must be non-negative.'):
validate_permutation({-1: 0, 0: -1})
with pytest.raises(IndexError, message='key is out of bounds.'):
validate_permutation({0: 3, 3: 0}, 2)
gate = SwapPermutationGate()
assert cirq.circuit_diagram_info(gate, default=None) is None
def acquaint_insides(
swap_gate: 'cirq.Gate',
acquaintance_gate: 'cirq.Operation',
qubits: Sequence['cirq.Qid'],
before: bool,
layers: Layers,
mapping: Dict[ops.Qid, int],
) -> None:
"""Acquaints each of the qubits with another set specified by an
acquaintance gate.
Args:
qubits: The list of qubits of which half are individually acquainted
with another list of qubits.
layers: The layers to put gates into.
acquaintance_gate: The acquaintance gate that acquaints the end qubit
with another list of qubits.
before: Whether the acquainting is done before the shift.
swap_gate: The gate used to swap logical indices.
mapping: The mapping from qubits to logical indices. Used to keep track
of the effect of inside-acquainting swaps.
"""
max_reach = _get_max_reach(len(qubits), round_up=before)
reaches = itertools.chain(range(1, max_reach + 1),
range(max_reach, -1, -1))
offsets = (0, 1) * max_reach
swap_gate = SwapPermutationGate(swap_gate)
ops = []
for offset, reach in zip(offsets, reaches):
if offset == before:
ops.append(acquaintance_gate)
for dr in range(offset, reach, 2):
ops.append(swap_gate(*qubits[dr:dr + 2]))
intrastitial_layer = getattr(layers, 'pre' if before else 'post')
intrastitial_layer += ops
# add interstitial gate
interstitial_layer = getattr(layers, ('prior' if before else 'posterior') +
'_interstitial')
interstitial_layer.append(acquaintance_gate)
# update mapping
reached_qubits = qubits[:max_reach + 1]
positions = list(mapping[q] for q in reached_qubits)
mapping.update(zip(reached_qubits, reversed(positions)))
def test_rectification():
qubits = cirq.LineQubit.range(4)
with pytest.raises(TypeError):
rectify_acquaintance_strategy(cirq.Circuit())
perm_gate = SwapPermutationGate()
operations = [
perm_gate(*qubits[:2]),
ACQUAINT(*qubits[2:]),
ACQUAINT(*qubits[:2]),
perm_gate(*qubits[2:])
]
strategy = cirq.Circuit.from_ops(operations,
device=UnconstrainedAcquaintanceDevice)
rectify_acquaintance_strategy(strategy)
actual_text_diagram = strategy.to_text_diagram().strip()
expected_text_diagram = """
0: ───────0↦1─────────█───
│ │
1: ───────1↦0─────────█───
2: ───█─────────0↦1───────
│ │
3: ───█─────────1↦0───────
""".strip()
assert actual_text_diagram == expected_text_diagram
strategy = cirq.Circuit.from_ops(operations,
device=UnconstrainedAcquaintanceDevice)
rectify_acquaintance_strategy(strategy, False)
actual_text_diagram = strategy.to_text_diagram()
expected_text_diagram = """
0: ───0↦1───────█─────────
│ │
1: ───1↦0───────█─────────
2: ─────────█───────0↦1───
│ │
3: ─────────█───────1↦0───
""".strip()
assert actual_text_diagram == expected_text_diagram