Improved TrySeparate()

TrySeparate() with a tolerance parameter has been improved, to avoid unnecessary entanglement when called in QUnit. As Decompose() also turns out to be a unitary operation in general, Separate() in the shared library API also no longer proactively normalizes its output subsystems.

Sparse state vector simulation was found to be bugged (under QUnit), and the official recommendation is that QBDD (QBdt) supersedes it in basically all regards, so sparse state vector simulation has been removed. (The argument to enable it remains behind in QInterface constructors so that this need not be a breaking change.)

What's Changed

• Cut sparse state vector by @WrathfulSpatula in #1018

Full Changelog: vm6502q.v9.11.8...vm6502q.v9.11.12

sha1sum results:
c2e5b97f4dcb784be2532693cfb590a8da11b8bc libqrack-macosx_14_0_arm64.zip
262da2fa86b4029d32427b2d8d465264adf473ca libqrack-macosx_15_0_arm64.zip
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Improve Separate() phase

Separate() and Decompose()/Dispose() phase angles are now weighted by contributing-amplitude probability (from the L2 norm).

Full Changelog: vm6502q.v9.11.0...vm6502qv9.11.4

sha1sum results:
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Debug QUnit Detach() edge case

QUnit::Decompose() had a long-standing bug: it failed to reindex QUnit "shards" in the destination simulation. This was fixed in a release yesterday, but the change introduced another problem in the indexing of the original simulator instance. Both issues have been fixed, in the current release.

Full Changelog: vm6502qv9.11.4...vm6502q.v9.11.8

sha1sum results:
4f1eae46796c5d886448e7f3fdfd8a528d72c8c2 libqrack-macosx_14_0_arm64.zip
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1a52a62cace8082e8b16cadd108bf8397fef8235 libqrack-manylinux2014_x86_64.zip
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a328df9caca74a6f947164285e3c6d3dd819e313 libqrack-win-amd64.zip

Separate() in shared library API

This release adds Separate() and Normalize() to the shared library API. Separate() forces entanglement-breaking between the target subsystem and all other qubits (without condition). Normalize() is a necessary component to achieve Separate() manually via Decompose().

A bug was fixed in QUnit::Decompose() in the course of testing Separate().

Full Changelog: vm6502q.v9.10.1...vm6502q.v9.11.0

sha1sum results:
ef2e584f25cd8ceee0a802af735f3d64bf6554c8 libqrack-macosx_14_0_arm64.zip
6cb9deb4f81d6d7b70ebd33ce914d6f2ae282bf6 libqrack-macosx_15_0_arm64.zip
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4ff75167921d15056d38c687b58330f56c210f6c libqrack-win-amd64.zip

SDRP/MPS correspondence base case

With all-to-all connectivity (but 0 bond dimension), SDRP (Schmidt decomposition rounding parameter) should reproduce the effective behavior of MPS (matrix product states) when the rounding parameter is set to 1 or greater: this release fixes the QUnit implementation to realize this theoretical expectation. (Disable QStabilizerHybrid layer and set the rounding parameter >= 1 to see this behavior, but the loss of "hybrid stabilizer" optimization should not qualitatively hurt performance in this case.)

Full Changelog: vm6502q.v9.10.0...vm6502q.v9.10.1

sha1sum results:
0e94263a661246fa548a8ae617e7f79a41d9c3be libqrack-macosx_14_0_arm64.zip
e929c7ddfc1445159e3ca08203cec7d5c98f677e libqrack-macosx_15_0_arm64.zip
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c3304b4a0b8c4e4cd831fbeae26963bf5deff7c1 libqrack-manylinux_2_35_x86_64.zip
984a41214ffedef4a4182d1038b0143a99c478e2 libqrack-manylinux_2_39_x86_64.zip
d62ebfc25eaa6ad01c7a7ef860d6d9881c2ccc58 libqrack-win-amd64.zip

Better sampling; OutProbs()

Multi-shot measurement in QEngine was previously handled in a way that was technically not thread-safe for C++. This has been fixed, and QEngine sampling has been parallelized further.

The OutProbs() method has been added to the shared library extern C API, which returns the L2 norm of each OutKet() amplitude in same order.

Full Changelog: vm6502q.v9.9.62...vm6502q.v9.10.0

sha1sum results:
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f4fb8a9365a50d8a45ce74ea4587a14f443d70df libqrack-macosx_15_0_arm64.zip
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Debug QBDD high rounding

If QRACK_QBDT_SEPARABILITY_THRESHOLD were set too high, it would previously lead to segmentation faults. This release should allow the rounding parameter to be set almost arbitrarily high.

Full Changelog: vm6502q.v9.9.58...vm6502q.v9.9.62

sha1sum results:
5f00f43db80fb218e08b32655b628dcdbea90423 libqrack-macosx_14_0_arm64.zip
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05f5b863349557ec517eb0692a30da67caae9e54 libqrack-win-amd64.zip

Debug QBDD sampling

This release fixes doubling-up of QBDD measurement sampling.

Full Changelog: vm6502q.v9.9.54...vm6502q.v9.9.58

sha1sum results:
48e945330d390dfe13e6d9669ddcb415d96b098c libqrack-macosx_14_0_arm64.zip
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QBDD optimization

A number of improvements have been made in QBDD simulation:

• PushStateVector() has more consistent flooring logic for very small contributions to overall state vector probability.
• Because QBDD gains little advantage from internal parallelism in most cases, internal parallelism in QBDD now defaults to OFF.
• If QBDD internal parallelism is off, then QTensorNetwork automatically parallelizes QBDD measurement sampling over shots

Full Changelog: vm6502q.v9.9.50...vm6502q.v9.9.54

sha1sum results:
10bea70febb145a1cd4adab85503d850ae40a116 libqrack-macosx_14_0_arm64.zip
0cd78e6a21e4ba5d071f74b543b596ed3d149b12 libqrack-manylinux2014_x86_64.zip
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8ee9c3597d4428b48d5d21ad85fd6724fee8897a libqrack-win-amd64.zip

Edge case segfault with 0 OpenCL/CUDA devices

This release fixes an edge case that leads to a segmentation fault, when QTensorNetwork is used in the presence of 0 available OpenCL/CUDA devices.

Full Changelog: vm6502q.v9.9.42...vm6502qv9.9.46

sha1sum results:
735297a892fb18177266d0133b904d3a522ba437 libqrack-macosx_14_0_arm64.zip
06c5149dbc4016b82a46cf2d9cfe6a40e30963a1 libqrack-manylinux2014_x86_64.zip
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