Generation QIR from QuTiP not working

[PariaNaghavi]

          To provide an example for generating qir from qutip, I have been referring to the [documentations](https://qutip-qip.readthedocs.io/en/latest/qip-simulator.html?highlight=qir#import-and-export-quantum-circuits); However, I encountered some issues. Specifically, it appears that the current version of qutip-qip (0.3.0) does not provide access to the `.qir` attribute nor the `circuit_to_qir` function. When attempting to import the [qir.py](https://github.com/qutip/qutip-qip/blob/master/src/qutip_qip/qir.py) locally, it is missing dependency on `pyqir.parser` which is gone in the current version of pyqir (0.7.0). This may be due to version incompatibility between the two libraries with the recent updates. 

Next, I adjusted the code to use the pyqir-generator instead of the parser, but I reached the following error about SNOT gate “not implemented in the QIR base profile and may require a custom declaration".

To replicate: Please see here Current outcome: An error due to missing .qir attribute and circuit_to_qir function in qutip-qip version and the missing dependency pyqir.parser Expected outcome: To generate qir, as shown in docs Notes: I would appreciate any suggestions or insights that might help in addressing these issues. Please let me know if there is any additional information or assistance that I can provide to fix this issue. Environment: QuTiP-QIP version: 0.0.3 pyqir version: 0.7.0 Python version: 3.9

Originally posted by @PariaNaghavi in https://github.com/qutip/qutip-qip/issues/125#issuecomment-1382605820

[BoxiLi]

Hi @PariaNaghavi

Sorry for the delay.

Two points:

• pyqir 0.7 merges pyqir-generator, pyqir-parser so now they are all in one package pyqir. This means that the importation in qir.py needs to be updated according. Use from pyqir import ... for everything (https://www.qir-alliance.org/pyqir/upgrade.html#pyqir-0-7). You kind of already solved this problem.
• The remaining error is because of from qutip.qip.circuit import QubitCircuit, Measurement, Gate. You are mixing the new package qutip_qip and the old module in the qutip main package qutip.qip. Although they share many similarities. They are not the same. Because you imported Gate from qutip.qip. They code in qir.py cannot recognize it. Please use from qutip_qip.circuit import QubitCircuit, Measurement, Gate instead.

[BoxiLi]

@cgranade Is it ok to drop the support of 0.6 and only support 0.7? Or should we try to keep it working both for 0.7 and 0.6? It seems quite cumbersome to support both because it is not just a change of version but rather the packages pyqir-generator and pyqir-parser are replaced by pyqir.

[PariaNaghavi]

Thank you @BoxiLi.

• Although from pyqir import generator works, I can not import the parser by from pyqir import parser. Please see the issue.
• Thanks for the hint on importing qutip_qip.circuit. I could try that on the qir.py file, once the parser is importable.

[BoxiLi]

With these changes (https://github.com/BoxiLi/qutip-qip/commit/d24b7b6c60a680644ec0f10dc775373bde1f2788) on qir.py and replacing qutip.qip with qutip_qip. I'm able to run through most of your ipynb.

[PariaNaghavi]

Thank you for the updates to the file. When I attempted to execute the updated qir.py file, I encountered an import error for Measurement from qutip_qip.operations. Any hints on how I can resolve this?

[BoxiLi]

You might be using an old version of the source code, not the one on the current master branch?

You can try from qutip_qip.circuit import Measurement, Gate.

[PariaNaghavi]

It works. Thank you! Just a gentle follow up, would you consider pushing the changes in qir.py on main?

[BoxiLi]

Yes, will soon make a PR on that.

[BoxiLi]

@cgranade Hi, could you maybe help us get the test updated for the new pyqir? I can get the code to work in (https://github.com/BoxiLi/qutip-qip/commit/d24b7b6c60a680644ec0f10dc775373bde1f2788) but have quite some difficulties updating the tests. It seems that the whole test file needs to be restructured because of the new interface?