# Circuit Library This module provides a library of [`BosonicGate`](../stubs/qiskit_bosons.circuit.BosonicGate.html.md#qiskit_bosons.circuit.BosonicGate) implementations. ## State preparation ## Passive linear optics A number-conserving transformation of the mode operators, generated by $b^\dagger_i b_j$. Beamsplitters and phase shifters are the two-mode and single-mode special cases, and together they generate any $U(M)$. ## Time evolution ### Synthesis methods How an [`Evolution`](../stubs/qiskit_bosons.circuit.library.Evolution.html.md#qiskit_bosons.circuit.library.Evolution) gate gets decomposed in bosonic space is configurable through its `synthesis` argument. The available methods live in the [`synthesis`](qiskit_bosons.circuit.library.synthesis.html.md#module-qiskit_bosons.circuit.library.synthesis) module.