Hiroshi Horii

Regarding 3: `bit[4] a` vs `bit a[4]` In #130, necessity of "return type" in subroutine `def` is discussed. I believe that a subroutine can return an array. If we keep...

Can we use an array for [an indexset of loop](https://qiskit.github.io/openqasm/language/classical.html#looping-and-branching)? Also, can we initialize elements of an array in its declaration? ``` array[int[64], 10] a = {0, 1, 2, 3,...

Once https://github.com/Qiskit/qiskit-terra/pull/5943 is merged, optimized parameters will be able to be store in user config around here: https://github.com/Qiskit/qiskit-aer/blob/9f7b832abf8c74ed6d04d62072ff000deae882ab/qiskit/providers/aer/profile.py#L68-L69 https://github.com/Qiskit/qiskit-aer/blob/9f7b832abf8c74ed6d04d62072ff000deae882ab/qiskit/providers/aer/profile.py#L82-L84

Here are performance graphs (`time_taken` includes only transpilation + simulation and excludes interface overheads) with default and tuned configurations. **Configurations:** - Left: MacBook (2.6 GHz 6-Core Intel Core i7) -...

@mtreinish OK. Please let me leave this as a placeholder for future change after qiskit-nature is released.

https://hhorii.github.io/qiskit-aer/html/#/ @mtreinish qiskit_nature was released and now it is good timing to work this again.

I'm not sure what is your problem in the above example because it does not work in my environment (`simulator2` and `circ2` are not defined when `simulator2.run(circ2).result()` is evaluated). On...

CPU uses [`AerPauliExpectation()`](https://github.com/Qiskit/qiskit-terra/blob/5f77531a1baf4b13609b46404ec18f84b87e9eaf/qiskit/opflow/expectations/aer_pauli_expectation.py#L35), which provides better performance but GPU does not because [`is_aer_qasm()`](https://github.com/Qiskit/qiskit-terra/blob/5f77531a1baf4b13609b46404ec18f84b87e9eaf/qiskit/opflow/expectations/expectation_factory.py#L96-L97) checks [backend name is `aer_simulator_statevector`](https://github.com/Qiskit/qiskit-terra/blob/5f77531a1baf4b13609b46404ec18f84b87e9eaf/qiskit/utils/backend_utils.py#L201-L214) though the backend name of GPU is `aer_simulator_statevector_gpu`. The easiest workaround is...

I think extending `save_probability()` (by adding new keyword argument `states`) is better than adding a new function `save_specific_probability()`.

> the statevector simulator you have to do an exponential (in the number of qubits) amount of work adding up the probabilities to get the outcome you want on the...