Checklist

• 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.

Description

This PR introduces a complete Bloch sphere visualization framework implemented using Makie.jl, ported from qutip but optimized for Julia. The Bloch type is designed to display and interactively visualize qubit states, including support for vectors, points, annotations, and more, with full customization.

Related issues or PRs

Closes #461

Features

Core Type

• Bloch struct that holds figure, scene, and all style/data attributes.
• Configurable view angles, background toggle, and figure size.

Plotting Capabilities

• add_points! to add raw (x, y, z) points.
• add_states! to convert Qobj qubit states into Bloch coordinates and plot as either vectors or points.
• add_vectors! to add custom 3D directional vectors.
• add_annotation! to label specific positions with text or LaTeX (via L-strings).
• add_line! and add_arc! to draw between points/states on the sphere.

Customization

• Set label conventions ("original", "xyz", "polarization jones", etc.) using set_label_convention!.
• Adjust colors, font sizes, sphere/frame styles, and transparency.

Export & Display

• Support for Base.show in both image/png and image/svg+xml mimetypes (IPython/Jupyter compatibility).
• save method to export the figure to disk with optional directory and DPI configuration.
• show! for interactive viewing via display.

Code Preview

• Example 1

using QuantumToolbox
using GLMakie

b = Bloch()
add_states!(b, Qobj([1, 0]), kind="vector", colors="red")
add_states!(b, Qobj([0, 1]), kind="vector", colors="blue")
add_states!(b, Qobj([1/√2, -1/√2]), kind="vector", colors="green")
add_annotation!(b, (-1.1, 0, 0), "|-⟩")
show!(b)

• Example 2

using QuantumToolbox
using GLMakie

b = Bloch()

add_points!(b, [0.0, 0.0, 1])
add_points!(b, [0.0, 0.0, -1])
add_points!(b, [
    [0.41, 0.2, 1.0], 
    [0.41, 0.3, -1.0], 
    [0.41, -1.0, 1.0], 
    [0.41, -1.0, -1.0]
], meth="l")

add_states!(b, rand_ket(2))
add_vectors!(b, [0, 0, 1]; alpha=0.4)

add_line!(b, rand_ket(2), rand_ket(2))
add_arc!(b, rand_ket(2), rand_ket(2))

show!(b)

API Summary

Bloch, set_label_convention!, clear!, add_points!,
add_states!, add_vectors!, add_annotation!,
add_line!, add_arc!, render!, show!