AerState::probability does not work as expected with the stabilizer simulator

[aromanro]

Informations

• Qiskit Aer version: Latest development version
• Python version: Irrelevant, as it's called from C++
• Operating system: Windows, linux, macos

What is the current behavior?

Calling AerState::probability throws an exception with the message "Save amplitude square must be defined on full width of qubits."
The exception comes from here:

qiskit-aer/src/simulators/stabilizer/stabilizer_state.hpp

Line 578 in 269c26f

if (num_qubits != BaseState::qreg_.num_qubits()) {

Steps to reproduce the problem

Configure a stabilizer simulator then call 'probability' for an outcome.

What is the expected behavior?

Return the probability.

Suggested solutions

Modify AerState::probability to add the list of qubits, that is, insert

  for (uint_t i = 0; i < num_of_qubits_; ++i)
    op.qubits.push_back(i);

somewhere here:

qiskit-aer/src/controllers/state_controller.hpp

Line 1382 in 269c26f

op.save_type = Operations::DataSubType::list;

This issue is similar with this one: #2234