Version 4.5.0

[sansiro77]

Modifications specific to this PR are marked in bold.

Features

• Optimize get_unitary for QumodeCircuit
• Add the iSWAP gate
• Optimize get_unitary for QumodeCircuit on GPUs
• Wigner function implementation from Fock state tensor
• Support the expectation value of photon number operator and quadrature operator for Fock backend (basis=False)
• Support vmap over multiple instances of QumodeCircuit
• Use block sampling to accelerate measurement for Fock backend

Fix

• Avoid the calculation of Fock probabilities for Bosonic backend
• Fix 'photon_number_mean_var' for Bosonic backend on GPUs
• Fix the post-processing of chain-rule sampling on specific wires for Gaussian backend
• Fix get_unitary of QumodeCircuit for VMAP
• Fix numerical instability in higher-order gradients of Hafnian
• Update dependencies and fix Wigner function
• Fix the dynamic update of Fock basis states and refactor QumodeCircuit
• Fix chain-rule sampling with threshold detector for Gaussian backend

Workflow

• Update docs and configure Ruff/Jupytext/Pre-commit
• Overhaul project structure, developer workflow, and documentation
• Exclude symlinks from pre-commit to fix Windows compatibility
• Add .git-blame-ignore-revs and .readthedocs.yaml
• Pin setuptools<82.0.0 to fix strawberryfields dependency

Docs

• Update descriptions of sampling method in photonic_basics.ipynb
• Update the old API of example notebook for optimizer
• Add docstrings for the argument loop_gates
• Update benchmark scripts
• Update README
• Update GBS examples
• Add attribution to Graphix for refactored functions
• Update legal headers for TensorCircuit and tensorgrad
• Update docstrings