Transformers (eg: optimized_for_sycamore) unroll circuit operations by default. #5039
Description
Description of the issue
Calling cirq.optimized_for_sycamore on a circuit with a CircuitOperation is expected to optimize only the contents of the CircuitOperation while preserving the structure, but the circuit is instead flattened.
How to reproduce the issue
import cirq_google
q0, q1 = cirq.LineQubit.range(2)
cop = cirq.CircuitOperation(
cirq.FrozenCircuit(
cirq.H(q0),
cirq.CX(q0, q1),
cirq.measure(q0, key='r1a'),
cirq.measure(q1, key='r1b'),
)
)
circuit = cirq.Circuit(cop.repeat(3))
syc_circuit = cirq_google.optimized_for_sycamore(circuit)
# circuitops have been flattened
print(syc_circuit)
Cirq version
0.14.0.dev20220228000741