QuantumToolboxCore Library

[ytdHuang]

Checklist

Thank you for contributing to QuantumToolbox.jl! Please make sure you have finished the following tasks before opening the PR.

• Please read Contributing to Quantum Toolbox in Julia.
• Any code changes were done in a way that does not break public API.
• Appropriate tests were added and tested locally by running: make test.
• Any code changes should be julia formatted by running: make format.
• All documents (in docs/ folder) related to code changes were updated and able to build locally by running: make docs.
• (If necessary) the CHANGELOG.md should be updated (regarding to the code changes) and built by running: make changelog.

Request for a review after you have completed all the tasks. If you have not finished them all, you can also open a Draft Pull Request to let the others know this on-going work.

Description

Describe the proposed change here.

Related issues or PRs

Please mention the related issues or PRs here. If the PR fixes an issue, use the keyword close/closes/closed/fix/fixes/fixed/resolve/resolves/resolved followed by the issue id, e.g. fix #[id]

Additional context

[github-actions]

⚠️ Performance Alert ⚠️

Possible performance regression was detected for benchmark 'Benchmark Results'.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.30.

Benchmark suite	Current: c68d51d	Previous: 8dcc0c5	Ratio
Correlations and Spectrum/Spectrum/Pseudo Inverse	33590623.5 ns	19493452 ns	1.72

This comment was automatically generated by workflow using github-action-benchmark.

[codecov]

Codecov Report

❌ Patch coverage is 58.76289% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.60%. Comparing base (0d68fbe) to head (c68d51d).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/QuantumToolboxUtils/src/type_handle.jl	41.46%	24 Missing ⚠️
lib/QuantumToolboxUtils/src/physics_func.jl	14.28%	6 Missing ⚠️
lib/QuantumToolboxUtils/src/PhysicalConstants.jl	0.00%	4 Missing ⚠️
lib/QuantumToolboxUtils/src/linalg/linalg.jl	0.00%	4 Missing ⚠️
lib/QuantumToolboxUtils/src/versioninfo.jl	96.77%	1 Missing ⚠️
...antumToolboxUtils/test/versioninfo_and_settings.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #686      +/-   ##
==========================================
- Coverage   93.25%   91.60%   -1.66%     
==========================================
  Files          57       63       +6     
  Lines        3914     3942      +28     
==========================================
- Hits         3650     3611      -39     
- Misses        264      331      +67     

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[ytdHuang]

This PR is also the first implementation related to issue #675

[ytdHuang]

As discussed in the admin meeting on May 6, 2026, we are going to introduce QuantumToolboxCore directly.

Several rename works still need to be done.