# Decomposition problem with Qiskit circuits

[andreamari]

If an error is obtained during the qiskit -> qasm -> cirq conversion, Mitiq tries to decompose the Qiskit circuit into
more elementary gates.

This trick works in some simple cases but not in many other similar cases. It looks like the Qiskit circuit sometimes is not fully decomposed.

The consequences are quite relevant since one gets errors for e.g. the very common gate 'rzz' .

Code to reproduce the issue:

from mitiq.interface import convert_to_mitiq

test_qc = QuantumCircuit(2)
test_qc.rx(0.1, 0)
test_qc.rzz(0.1, 0, 1)  # If you remove this line it works!
print(test_qc)
convert_to_mitiq(test_qc)

[gluonhiggs]

I have created a PR to resolve this issue here.
P/s:
Initially I thought we could decompose the circuit before using convert_to_mitiq, however that's just a workaround. Mitiq should automatically do that for us. Hence, I tried to resolve the issue as in the PR.