Static stabilizer, CUDA bug fix, and style improvements

Statically linked QStabilizerHybrid code now benefits from additional caching when querying multiple expectation values at the same point in unitary circuit evolution. As of this release, environment variables always preempt user code methods for near-Clifford rounding threshold.

An ENABLE_CUDA macro was misspelled in code, affecting (CUDA) stabilizer simulation.

For readability, Qrack adopts a style convention that functions and methods with multiple return-or-throw statement points put extra line breaks before and after every return statement unless either instance coincides with the beginning or end of scope, and any inner-scope returns (except top-level lambda function scope) have extra line breaks above and below the containing scope (as necessary). (Pardon the unreadable diff on Qrack, for this change in particular.)

Full Changelog: vm6502q.v9.13.37...vm6502q.v9.14.0

sha1sum results:
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4f4b992749718239a03a3d390b31429ab8a1bbe2 libqrack-win-amd64.zip

Style fixes (nullptr)

Previously, Qrack relied on NULL when necessary for pointers. In this release, all instances of NULL have been replaced with nullptr (since this was added in C++11, as far back as Qrack supports for a C++ standard). This surfaced exactly one instance of NULL where nullptr was not immediately appropriate, because NULL was assigned to a variable for an instance of a class rather than a pointer to the class. Deeming this a "code smell" (even though it's very unlikely there could have been any bad access, use-after-free, or other memory safety error, here) the code was refactored to achieve its same original intent while using nullptr instead. Also, for loops have been brought up to standard for use of the "foreach" pattern (for (auto& x : container)).

Full Changelog: vm6502q.v9.13.33...vm6502q.v9.13.37

sha1sum results:
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4a33ab54b167fe4efd5dd9de17787dcadecc323b libqrack-macosx_15_0_arm64.zip
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5d6cc4b8f7509ef90446d355d97a5e30ac9ee603 libqrack-win-amd64.zip

QUnit micro-optimization (and fix Windows builds)

This release adds micro-optimizations to for loops in QUnit. We also have a pull request to fix Windows debug builds. (We also work around the fact that Microsoft is once again either "lawyering" or attempting to redefine the C++ standard, for std::chrono::system_clock, in their latest compiler release, which, if the latter, will fail.)

What's Changed

• Castorena/msvc build by @crcastore in #1019
• Various micro-optimizations by @WrathfulSpatula

New Contributors

• @crcastore made their first contribution in #1019

Full Changelog: vm6502q.v9.13.29...vm6502q.v9.13.33

sha1sum results:
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"Detailing"

This patch release enforces Qrack idiomatic style. Specifically, a "foreach" pattern (for(const auto& x : container)) should be preferred when sequence or index do not matter; a loop over index should be preferred when index or sequence matters. (In practice, "foreach" over the elements of a std::vector, for example, will probably always proceed in stable order according to index, but Qrack style demands that this should be reflected explicitly in the code idiom.) Catch2 for unit tests and benchmarks has also been upgraded to the last official major v2 release.

Full Changelog: vm6502q.v9.13.25...vm6502q.v9.13.29

sha1sum results:
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Fix uniformly controlled signatures; stabilizer micro-optimizations

What motivates this release is a problem fixed in the signatures of "uniformly controlled" gates (such as QNeuron relies upon). Historically, I had confused const type* for type const* in cases. This was meant to be totally fixed in a previous release, but editing documentation surfaced the remaining inconsistency in uniformly controlled gate signatures. The change does not break anything in the library, so there was no bad access, despite the erroneous types. Besides that, this release includes (likely insignificant) optimizations for stabilizer simulation.

Expect Ubuntu releases, since it's important that they have the right C++ signatures.

Full Changelog: vm6502q.v9.13.24...vm6502q.v9.13.25

sha1sum results:
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182f044c67d583087072caadbcb1dc51daf0c2d7 libqrack-macosx_15_0_arm64.zip
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Semantic version bump for downstream projects

Almost the only point of this release is to clarify Qrack's semantic versioning as tracked in downstream projects (like pyqrack). Since last release, minor style improvements were made in stabilizer simulation that might give a (probably very tiny) performance increase. The README was also comprehensively reorganized and improved. Windows builds might see an improvement from fixing a problem with use of /O3 compiler flag in CMake. (It is unlikely that Ubuntu packages will be updated for now, for this semantic release, before meaningfully substantive improvements are made in Qrack functionality at a later time.)

Full Changelog: vm6502q.v9.13.16...vm6502q.v9.13.24

sha1sum results:
8f134387d809b1ace091688c1eaf11e59ca987b6 libqrack-macosx_14_0_arm64.zip
3b69d8b9a97dad6f03036643f7a7d7efddb99072 libqrack-macosx_15_0_arm64.zip
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QCircuit commutation

In this release, QCircuit checks, when a gate commutes, whether it had any qubits in common with the other gate. If it does, commutation is deemed "productive," and circuit optimization continues. If commutation only occurs without any qubits in common between commuting gates, and if the gate ultimately fails to commute at the last step, then commutation is deemed "non-productive," and the corresponding qubits are removed from the circuit optimization light cone.

Full Changelog: vm6502q.v9.13.9...vm6502q.v9.13.16

sha1sum results:
36ea69309bdada8dcf7a585139b4a5763f5aabb8 libqrack-macosx_14_0_arm64.zip
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QCircuit light cone

QCircuit has been improved with further light-cone optimizations. Now, when gates are combined to produce identity operator somewhere mid-circuit, only gates in the light cone are checked for further composability past the identity gate, and, as gates in the light cone fail to produce any further improvements past a certain depth, the blocked wires are removed from the light cone for further optimization checks. (These improvements are inspired by consideration of "directed acyclic graph," "DAG" data structures.)

Full Changelog: vm6502q.v9.13.8...vm6502q.v9.13.9

sha1sum results:
b17d9a3437ecebbc9fb3802e56a53a068be51152 libqrack-macosx_14_0_arm64.zip
b9fa424e04cc203948f155eca2dd5ee774c9e8ac libqrack-macosx_15_0_arm64.zip
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fc6ec66a81819c6b18d8d910406472660a58d7ea libqrack-win-amd64.zip

PSTRIDEPOW default; QCircuit improvement

(With apologies for two release iterations in a day...) Environment/build option PSTRIDEPOW default value has been re-tuned based on local benchmarks. In QCircuit, we noticed that Swap gate could be decomposed as either 3 CNOT or 3 AntiCNOT gates, which can improve performance.

Full Changelog: vm6502q.9.13.7...vm6502q.v9.13.8

sha1sum results:
eeb489e7c6d71e2e5e78537d9273fee6018110a5 libqrack-macosx_14_0_arm64.zip
8cbe0548fc8bd2b25067b30ed8eb7ca83a0dc1e2 libqrack-macosx_15_0_arm64.zip
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d12774e34c689439cb173a90ba15e90bf3c1d975 libqrack-win-amd64.zip

Improve QCircuit

This release reverts the fixed-precision reporting of IO streams and improves the performance of QCircuit.

Full Changelog: vm6502q.v9.13.6...vm6502q.9.13.7

sha1sum results:
a456a5d8cbffda153cee32c0bf683028b978726f libqrack-macosx_14_0_arm64.zip
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