# Qiskit's PauliTrotterEvolution yields weird gates

I am trying to work with Qiskit's PauliTrotterEvolution() module, but the resulting circuits contain weird gates that I know nothing about.

Here is a simple example: I want to implement the fermionic creation operator on one of two qubits

from qiskit_nature.mappers.second_quantization import BravyiKitaevMapper
from qiskit_nature.operators.second_quantization import FermionicOp
from qiskit.opflow.evolutions import PauliTrotterEvolution

fermi_op = FermionicOp("+I", display_format="dense")


The fermionic operator is mapped to a sum of Pauli gates using the Bravyi-Kitaev mapper:

mapper = BravyiKitaevMapper()
bosonic_op = mapper.map(fermi_op)


Now we apply the PauliTrotterEvolution to the exponential of the bosonic operator:

pauli_trotter = PauliTrotterEvolution("trotter", reps=1)

conv = pauli_trotter.convert(bosonic_op.exp_i())

circ = conv.to_circuit()

circ.draw("latex")


I have no clue what these "circuit" gates are. Has anyone seen something similar before?

These "circuit" gates are empty, if you transpile the circuit to a basis gate set they will disappear:

from qiskit import transpile