qtree circuit is a list of lists, but simulator takes a list of gates

[danlkv]

qtree code assumes that gates are grouped in "layers". The qtree circuits are lists of lists of gates. The layer information is not very useful, so in qtensor circuit is just a list of qtree gates.

This can cause the following error (for example when creating TensorNet):

File ".../qtensor/optimisation/TensorNet.py", line 63, in <listcomp>
    n_qubits = len(set(sum([g.qubits for g in all_gates], tuple())))
AttributeError: 'list' object has no attribute 'qubits'

In examples the conversion is mentioned, but ideally there shouldn't be a conversion involved.

n, qc = from_qiskit_circuit(qiskit_qaoa.circuit)
all_gates = sum(qc, [])
sim.simulate(all_gates)