Approximate Quantum Compiler

[adekusar-drl]

Summary

This is an implementation of Approximate Quantum Compiler from the paper "Best Approximate Quantum Compiling Problems", https://arxiv.org/abs/2106.05649. The implementation is a minimal version and does not include all features from the referenced paper.

Details and comments

The implementation includes:

• An approximate quantum compiler as it is referenced in the paper.
• An AQC based unitary synthesis plugin for transpiler that depends on the PR: Add unitary synthesis plugin interface #6124

Authors:

• Liam Madden
• Andrea Simonetto
• Albert Akhriev

[adekusar-drl]

In testing, I came across the following error, but it's not clear to me where it originates:

@kdk All works on my laptop and I get an identity matrix in the end. I don't know what caused this error, unfortunately. I added a test case with this snippet, this case is closer to the actual workflow of the transpiler.

[1ucian0]

In testing, I came across the following error, ...

As @adekusar-drl , I also was unable to reproduce this issue.

[kdk]

In testing, I came across the following error, ...

As @adekusar-drl , I also was unable to reproduce this issue.

Upgrading to scipy 1.5 resolved this for me. Can you check if this is compatible with scipy 1.4 and update the requirements.txt if not?

[adekusar-drl]

@kdk I can confirm there are issues with scpi 1.4. I have another error, not the same as you had. Despite it is a deprecation, the tests fail. So, I think it is safer to upgrade the requirements. Please take a look and thanks for spotting this issue.

Error
testtools.testresult.real._StringException: Traceback (most recent call last):
  File ".../qiskit-terra/test/python/transpiler/aqc/test_aqc.py", line 56, in test_aqc
    initial_point=np.array(INITIAL_THETAS),
  File ".../qiskit-terra/qiskit/transpiler/synthesis/aqc/aqc.py", line 99, in compile_unitary
    jac=approximating_objective.gradient,
  File ".../qiskit-terra/qiskit/algorithms/optimizers/scipy_optimizer.py", line 136, in minimize
    **self._kwargs,
  File ".../envs/dev-terra/lib/site-packages/scipy/optimize/_minimize.py", line 610, in minimize
    callback=callback, **options)
  File ".../envs/dev-terra/lib/site-packages/scipy/optimize/lbfgsb.py", line 339, in _minimize_lbfgsb
    task_str = task.tostring()
DeprecationWarning: tostring() is deprecated. Use tobytes() instead.

[coveralls]

Pull Request Test Coverage Report for Build 1494293906

• 410 of 428 (95.79%) changed or added relevant lines in 8 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.09%) to 82.761%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/transpiler/synthesis/aqc/cnot_unit_objective.py	131	132	99.24%
qiskit/transpiler/synthesis/aqc/elementary_operations.py	15	16	93.75%
qiskit/transpiler/synthesis/aqc/cnot_unit_circuit.py	40	42	95.24%
qiskit/transpiler/synthesis/aqc/approximate.py	28	34	82.35%
qiskit/transpiler/synthesis/aqc/cnot_structures.py	106	114	92.98%

Totals
Change from base Build 1490628111:	0.09%
Covered Lines:	50173
Relevant Lines:	60624

---

💛 - Coveralls

[adekusar-drl]

@kdk recent changes include:

• Unit tests for cnot networks as discussed with @1ucian0.
• Address changes introduced in Add option to unitary synthesis plugin interface for user config #7252

[adekusar-drl]

Hi @kdk are there any news on the PR?

[kdk]

Thanks for the updates! This LGTM.