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Replace SwapPermutationReplacer with cirq.map_operations #5655

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merged 6 commits into from
Jul 6, 2022
Merged

Replace SwapPermutationReplacer with cirq.map_operations #5655

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d3a5160
Remove stale TODO
tanujkhattar Jun 29, 2022
198c2f7
Merge branch 'master' of https://github.com/quantumlib/cirq
tanujkhattar Jun 29, 2022
e1b985b
Merge branch 'master' of https://github.com/quantumlib/cirq into remo…
tanujkhattar Jun 30, 2022
fe04316
Remove SwapPermutationReplacer
tanujkhattar Jun 30, 2022
d8b641e
Merge branch 'master' into remove_swap_permutation_replacer
vtomole Jul 6, 2022
d91f451
Merge branch 'master' into remove_swap_permutation_replacer
MichaelBroughton Jul 6, 2022
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30 changes: 10 additions & 20 deletions cirq-core/cirq/contrib/quantum_volume/quantum_volume.py
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Original file line number Diff line number Diff line change
Expand Up @@ -197,24 +197,6 @@ def process_results(
return data


class SwapPermutationReplacer(cirq.PointOptimizer):
"""Replaces SwapPermutationGates with their underlying implementation
gate."""

def __init__(self):
super().__init__()

def optimization_at(
self, circuit: cirq.Circuit, index: int, op: cirq.Operation
) -> Optional[cirq.PointOptimizationSummary]:
if isinstance(op.gate, cirq.contrib.acquaintance.SwapPermutationGate):
new_ops = op.gate.swap_gate.on(*op.qubits)
return cirq.PointOptimizationSummary(
clear_span=1, clear_qubits=op.qubits, new_operations=new_ops
)
return None # Don't make changes to other gates.


def compile_circuit(
circuit: cirq.Circuit,
*,
Expand Down Expand Up @@ -296,7 +278,15 @@ def compile_circuit(
mapping = swap_networks[0].final_mapping()
# Replace the PermutationGates with regular gates, so we don't proliferate
# the routing implementation details to the compiler and the device itself.
SwapPermutationReplacer().optimize_circuit(routed_circuit)

def replace_swap_permutation_gate(op: 'cirq.Operation', _):
if isinstance(op.gate, cirq.contrib.acquaintance.SwapPermutationGate):
return [op.gate.swap_gate.on(*op.qubits)]
return op

routed_circuit = cirq.map_operations_and_unroll(
routed_circuit, map_func=replace_swap_permutation_gate
)

if not compiler:
return CompilationResult(circuit=routed_circuit, mapping=mapping, parity_map=parity_map)
Expand All @@ -307,7 +297,7 @@ def compile_circuit(
# as well, we allow this to be passed in. This compiler is not allowed to
# change the order of the qubits.
return CompilationResult(
circuit=compiler(swap_networks[0].circuit), mapping=mapping, parity_map=parity_map
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@vtomole vtomole Jul 6, 2022 •
edited

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Why was swap_networks[0].circuit being passed in in the first place instead of routed_circuit?

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Because the original optimizer mutated the circuit. routed_circuit was a variable storing a reference to swap_networks[0].circuit and since the underlying circuit was being mutated; it didn't matter whether you pass swap_networks[0].circuit or routed_circuit.

Now, routed_circuit stores a modified copy of swap_networks[0].circuit and therefore we need to pass routed_circuit instead of swap_networks[0].circuit.

circuit=compiler(routed_circuit), mapping=mapping, parity_map=parity_map
)


Expand Down