Propagators

Propagators implement the unitary time evolution for different types of operators. Choose the appropriate propagator based on your operator’s structure.

Predefined unitary classes for simulation of the action of QVA phase-shift and mixing unitaries with compatible Operator Functions.

Table 1 Propagator Selection Guide

Propagator	Use When	Example Applications
Circulant	Operator is circulant (translation-invariant)	QWOA, constrained combinatorial optimisation
Diagonal	Operator is diagonal in computational basis	Phase operators, cost Hamiltonians
Sparse	Operator is a general sparse matrix	QAOA, custom Hamiltonians
Composite	Operator is a Cartesian sum of circulant operators mixing over subregisters	Discretised continuous multivariable optimisation, combinatorial problems with decision variables of arity >= 3
Momentum	State evolves in momentum space	Gradient-descent search inspired by continuous-variable photonic quantum computing

• Circulant
• Diagonal
• Sparse
• Composite
• Momentum