Automatic Uniform Quantum State Preparation Using Decision Diagrams

Most quantum algorithms assume some specific initial state in superposition of basis states before performing the desired application-specific computations. The preparation of such states itself requires a computation performed by a quantum circuit. In this paper, we investigate the automatic state preparation of a specific subset of quantum states that are uniform superpositions over a subset of basis states, called uniform quantum states. We exploit that such states can be represented using Boolean functions and present a recursive algorithm based on functional decomposition. When using binary decision diagrams as function representation, we can enable fast and scalable quantum state preparation with respect to the size of the decision diagram. We show that the algorithm can find quantum circuits for functions, where state-of-the-art algorithms cannot be applied anymore.