Extracting details of Circuits of QAOA and modify it.

[shangtai]

Hi,

I am trying to extract details of circuits of QAOA after I implement it in Qibo so that we can perform noise mitigation on it. May I know how can we do so?

For example, can we extract a list of the gates used?

After that, can we modify the list and construct a new circuit to be run?

[stavros11]

I had a quick look at the QAOA code and I think that by default it is not using circuits as it is just exponentiating the Hamiltonians and applying them to the state in a time evolution fashion.

If you are using SymbolicHamiltonian you can obtain the circuit that performs the evolution using qaoa.hamiltonian.circuit or qaoa.mixer.circuit and you can use various circuit properties, such as circuit.gate_types, circuit.summary() or just circuit.queue to get the gates. Or create other circuits based on this.

[shangtai]

Hi @stavros11,

I am considering if I should modify some of the code. Can I check how is exponentiation of the matrix implemented? If it's exponentiating the dense Hamiltonian matrix, for n qubits, are we expecting a matrix of 2^(2n) of complex floating point numbers?

Thanks.

@jf-kong and @shangtai