optimize_for_target_gateset does not return equivalent circuit #6517
Description
Description of the issue
The document says optimize_for_target_gateset returns "An equivalent circuit containing gates accepted by gateset." However, applying optimize_for_target_gateset to the below circuit generates a new circuit with a different final state vector.
Note that the final state vectors have a large difference (atol >= 1e-3).
How to reproduce the issue
import cirq
from cirq import *
qr = cirq.LineQubit.range(5)
qc = cirq.Circuit()
qc.append(XXPowGate(exponent=0.05914855949794997, global_shift=4.257271900551728).on(qr[0], qr[1]))
qc.append(Rz(rads=3.342979007376063).on(qr[2]))
qc.append(XXPowGate(exponent=2.3059912502413593, global_shift=5.787646153894631).on(qr[3], qr[4]).controlled_by(qr[1]))
new_qc = cirq.optimize_for_target_gateset(qc)
simulator = cirq.Simulator()
st1 = simulator.simulate(qc, qubit_order=sorted(qc.all_qubits())).final_state_vector
print(st1)
st2 = simulator.simulate(new_qc, qubit_order=sorted(new_qc.all_qubits())).final_state_vector
print(st2)
print(cirq.equal_up_to_global_phase(st1, st2, atol=1e-3))
[ 0.70258266-0.70552826j 0. -0.j 0. -0.j
0. -0.j -0. +0.j -0. +0.j
-0. +0.j -0. +0.j 0. -0.j
0. -0.j 0. -0.j 0. -0.j
-0. +0.j -0. +0.j -0. +0.j
-0. +0.j 0. -0.j 0. -0.j
0. -0.j 0. -0.j -0. +0.j
-0. +0.j -0. +0.j -0. +0.j
-0.05791184+0.05842676j 0. -0.j 0. -0.j
0.03046589+0.03019739j 0. +0.j -0. +0.j
-0. +0.j 0. -0.j ]
[ 7.0258260e-01-7.0552832e-01j -2.4170467e-07-2.0510472e-08j
3.4080244e-08+6.8633639e-08j 2.8088609e-08+9.3309067e-09j
-0.0000000e+00+0.0000000e+00j 0.0000000e+00+0.0000000e+00j
0.0000000e+00-0.0000000e+00j 0.0000000e+00-0.0000000e+00j
2.6692208e-09-1.9153942e-08j 2.3014948e-09-1.6515171e-08j
3.1672400e-08+4.4137511e-09j -9.9875805e-09-1.3918358e-09j
-0.0000000e+00+0.0000000e+00j -0.0000000e+00+0.0000000e+00j
0.0000000e+00-0.0000000e+00j 0.0000000e+00+0.0000000e+00j
2.6655547e-08-3.2647190e-08j 8.8367956e-16-8.9282454e-17j
-6.2901604e-16+1.1079911e-15j 5.5332231e-23+2.1014054e-23j
-0.0000000e+00+0.0000000e+00j -0.0000000e+00+0.0000000e+00j
0.0000000e+00+0.0000000e+00j 0.0000000e+00-0.0000000e+00j
-4.1379835e-02-9.9977581e-03j -3.5679083e-02-8.6203888e-03j
1.6532000e-02-6.8424508e-02j -5.2132001e-03+2.1576982e-02j
0.0000000e+00+0.0000000e+00j 0.0000000e+00+0.0000000e+00j
-0.0000000e+00+0.0000000e+00j 0.0000000e+00+0.0000000e+00j]
False
Cirq version
You can get the cirq version by printing cirq.__version__. From the command line:
1.3.0