State-preparation examples
==============================

Preparing the input register a primitive will consume. These examples build
chemistry-style states with the composable `stateprep` device kernels, each one
checked against a dense reference.

.. seealso::

   :doc:`../guide/state_prep` — the ansatz kernels, operator pools, and
   injection contract behind these examples.

Hartree-Fock and fixed-parameter UCCSD state preparation
--------------------------------------------------------

Prepares a 4-qubit / 2-electron UCCSD ansatz state at fixed amplitudes
(H2-style). It shows how the Hartree-Fock reference and the fixed-parameter
UCCSD singles and doubles compose into a single `state_prep` kernel.

.. literalinclude:: ../examples/python/hartree_fock_ucc.py
   :language: python
   :start-after: [Begin Documentation]

Givens-rotation Slater determinant preparation
----------------------------------------------

Prepares a real 4-orbital / 2-electron determinant and a complex 5-orbital /
3-electron determinant with the composable Givens-rotation `stateprep` kernels.
Both are validated against their dense Slater-determinant references.

.. literalinclude:: ../examples/python/givens_slater_determinant.py
   :language: python
   :start-after: [Begin Documentation]