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Merged
merged 6 commits into from
Jul 12, 2022
Merged

GridDevice: Exclude MeasurementGates in validation of qubit pairs #5654

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0bf3677
GridDevice: Exclude MeasurementGates in validation of qubit pairs
verult Jun 30, 2022
dfe5004
Added grid device tests for measuring more than 2 qubits
verult Jul 6, 2022
bbbfecb
WaitGate support
verult Jul 7, 2022
2098616
Changed 'subset permutation' to 'variadic'
verult Jul 12, 2022
2a6dd6c
Merge branch 'master' into cg-device-refactor/measure-two-qubits
CirqBot Jul 12, 2022
fefad64
Merge branch 'master' into cg-device-refactor/measure-two-qubits
CirqBot Jul 12, 2022
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4 changes: 4 additions & 0 deletions cirq-google/cirq_google/devices/grid_device.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,9 @@
MEASUREMENT_GATE_FAMILY = cirq.GateFamily(cirq.MeasurementGate)
WAIT_GATE_FAMILY = cirq.GateFamily(cirq.WaitGate)

# Families of gates which can be applied to any subset of valid qubits.
_SUBSET_PERMUTATION_GATE_FAMILIES = [MEASUREMENT_GATE_FAMILY, WAIT_GATE_FAMILY]
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Could we perhaps call this _VARIADIC_GATE_FAMILIES instead? I think the term "variadic" captures the property we want, that these are gates that can be applied to any number of qubits.

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I am going to remember this vocabulary word for when I take the Quantum SATs!



def _validate_device_specification(proto: v2.device_pb2.DeviceSpecification) -> None:
"""Raises a ValueError if the `DeviceSpecification` proto is invalid."""
Expand Down Expand Up @@ -338,6 +341,7 @@ def validate_operation(self, operation: cirq.Operation) -> None:

if (
len(operation.qubits) == 2
and not any(operation in gf for gf in _SUBSET_PERMUTATION_GATE_FAMILIES)
and frozenset(operation.qubits) not in self._metadata.qubit_pairs
):
raise ValueError(f'Qubit pair is not valid on device: {operation.qubits!r}.')
Expand Down
59 changes: 59 additions & 0 deletions cirq-google/cirq_google/devices/grid_device_test.py
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Expand Up @@ -252,15 +252,74 @@ def test_grid_device_from_proto():
def test_grid_device_validate_operations_positive():
device_info, spec = _create_device_spec_with_horizontal_couplings()
device = cirq_google.GridDevice.from_proto(spec)
# Gates that can be applied to any subset of valid qubits
subset_permutation_gates = [cirq.measure, cirq.WaitGate(cirq.Duration(nanos=1), num_qubits=2)]

for q in device_info.grid_qubits:
device.validate_operation(cirq.X(q))
device.validate_operation(cirq.measure(q))

# horizontal qubit pairs
for i in range(GRID_HEIGHT):
device.validate_operation(
cirq.CZ(device_info.grid_qubits[2 * i], device_info.grid_qubits[2 * i + 1])
)
for gate in subset_permutation_gates:
device.validate_operation(
gate(device_info.grid_qubits[2 * i], device_info.grid_qubits[2 * i + 1])
)


@pytest.mark.parametrize(
'gate_func',
[
lambda _: cirq.measure,
lambda num_qubits: cirq.WaitGate(cirq.Duration(nanos=1), num_qubits=num_qubits),
],
)
def test_grid_device_validate_operations_subset_permutation_gates_positive(gate_func):
device_info, spec = _create_device_spec_with_horizontal_couplings()
device = cirq_google.GridDevice.from_proto(spec)

# Single qubit operations
for q in device_info.grid_qubits:
device.validate_operation(gate_func(1)(q))

# horizontal qubit pairs (coupled)
for i in range(GRID_HEIGHT):
device.validate_operation(
gate_func(2)(device_info.grid_qubits[2 * i], device_info.grid_qubits[2 * i + 1])
)

# Subset permutation gates across vertical qubit pairs (uncoupled pairs) should succeed.
for i in range(GRID_HEIGHT - 1):
device.validate_operation(
gate_func(2)(device_info.grid_qubits[2 * i], device_info.grid_qubits[2 * (i + 1)])
)
device.validate_operation(
gate_func(2)(
device_info.grid_qubits[2 * i + 1], device_info.grid_qubits[2 * (i + 1) + 1]
)
)
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Would be good to add some test cases of measurement on more qubits, for example triplets of qubits or all qubits (cirq.measure(*device_info.grid_qubits)).


# 3-qubit measurements
for i in range(GRID_HEIGHT - 2):
device.validate_operation(
gate_func(3)(
device_info.grid_qubits[2 * i],
device_info.grid_qubits[2 * (i + 1)],
device_info.grid_qubits[2 * (i + 2)],
)
)
device.validate_operation(
gate_func(3)(
device_info.grid_qubits[2 * i + 1],
device_info.grid_qubits[2 * (i + 1) + 1],
device_info.grid_qubits[2 * (i + 2) + 1],
)
)
# All-qubit measurement
device.validate_operation(gate_func(len(device_info.grid_qubits))(*device_info.grid_qubits))


def test_grid_device_validate_operations_negative():
Expand Down