Fix #177: Correct pattern export to OpenQASM 3 #404
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This commit introduces `pattern_to_qasm3`, improving the export of patterns to OpenQASM 3: - Planes YZ and XZ are now handled correctly (TeamGraphix#177). - For plane XY, the angle is no longer ignored when the s-domain is empty. - Support for |0⟩ and |+⟩ initial states. - Arithmetic expressions unsupported by `qiskit-qasm3-import` are replaced with a simpler encoding, and the `single_qubit_domains` pass ensures compatibility with Qiskit. - `test_qasm3_exporter_to_qiskit.py` verifies that the Graphix pattern simulator and Qiskit AER simulator produce equivalent statevectors for exported circuits. Additionally, this commit fixes a regression from TeamGraphix#312: statevectors are now properly normalized.
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## master #404 +/- ##
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+ Coverage 85.03% 85.57% +0.54%
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graphix/qasm3_exporter.py
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| yield 'include "stdgates.inc";\n' | ||
| yield "\n" | ||
| for node in pattern.input_nodes: | ||
| yield f"// prepare input qubit {node} in |+⟩\n" |
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Isn't this misleading, since input qubits may be prepared in |+> or |0> ?
I think it should be moved to the branch elif state == BasicStates.PLUS: in :func: state_to_qasm3_lines, or alternatively
f"// prepare input qubit {node} in |+⟩ or |0⟩\n"There was a problem hiding this comment.
Nice catch! This is now fixed.
| condition = " ^ ".join(f"c{node}" for node in domain) | ||
| if not condition: | ||
| return | ||
| yield f"if ({condition}) {{\n" |
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Is it possible that there's one { too many?
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In f-strings, { should be doubled to appear in the final string. https://docs.python.org/3/reference/lexical_analysis.html#f-strings:
Any doubled curly braces ({{ or }}) outside replacement fields are replaced with the corresponding single curly brace:
print(f'{{...}}') {...}
graphix/qasm3_exporter.py
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| if cmd.plane == Plane.XY: | ||
| yield f"h q{cmd.node};\n" | ||
| if cmd.angle != 0: | ||
| rad_angle = angle_to_rad(cmd.angle) |
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Shouldn't we use angle_to_qasm3 ? (This would prevent errors if the cmd.angle is parametric).
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Yes, you are right, angle_to_qasm3 is better here. This is fixed.
| yield f"rx({-rad_angle}) q{cmd.node};\n" | ||
| elif cmd.plane == Plane.XZ: | ||
| yield f"ry({-rad_angle}) q{cmd.node};\n" | ||
| else: |
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To improve readability, I would suggest putting elif cmd.plane == Plane.YZ followed by typing_extensions.assert_never (or match. Actually I'm not sure if there is an advantage on using match over chained if-else, or if it's just a matter of taste. Would we need typing_extensions.assert_never if we were using match ?)
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Fixed. There is no default exhaustiveness check with match in Python, any more than with chained if/elif: we need to add a default clause, case e: assert_never(e), to ensure exhaustiveness.
graphix/qasm3_exporter.py
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| See :func:`pattern_to_qasm3`. | ||
| """ | ||
| yield "// generated by graphix\n" |
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Could it be useful to add graphix version here ? Not sure if we expose it at the moment, if not, I wouldn't bother adding it to this PR.
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Good idea. Fixed.
3 participants
This commit introduces
pattern_to_qasm3, improving the export of patterns to OpenQASM 3:Planes YZ and XZ are now handled correctly (QASM3 export only supports XY plane measurements #177).
For plane XY, the angle is no longer ignored when the s-domain is empty.
Support for |0⟩ and |+⟩ initial states.
Arithmetic expressions unsupported by
qiskit-qasm3-importare replaced with a simpler encoding, and thesingle_qubit_domainspass ensures compatibility with Qiskit.test_qasm3_exporter_to_qiskit.pyverifies that the Graphix pattern simulator and Qiskit AER simulator produce equivalent statevectors for exported circuits.