Quantum Circuit Ansatz: Patterns of Abstraction and Reuse of Quantum Algorithm Design

TL;DR

This paper addresses fragmentation in quantum circuit design by compiling a catalog of quantum circuit ansatzes to aid algorithm design and implementation. Ansatze are described with fields such as Intent, Motivation, Applicability, Circuit Diagram, Implementation, Example, and See Also, enabling structured comparison; for variational methods, energy optimization targets like $E(\theta) = \langle \psi(\theta)|H|\psi(\theta)\rangle$ are minimized. The catalog spans major VQA families (VQE, QAOA, QML) and includes a platform-support survey across leading quantum hardware and software ecosystems. By enabling abstraction and reuse, the resource supports informed ansatz selection, accelerates design iterations, and highlights directions for future research in hardware-aware quantum algorithms.

Abstract

Quantum computing holds the potential to revolutionize various fields by efficiently tackling complex problems. At its core are quantum circuits, sequences of quantum gates manipulating quantum states. The selection of the right quantum circuit ansatz, which defines initial circuit structures and serves as the basis for optimization techniques, is crucial in quantum algorithm design.This paper presents a categorized catalog of quantum circuit ansatzes aimed at supporting quantum algorithm design and implementation. Each ansatz is described with details such as intent, motivation, applicability, circuit diagram, implementation, example, and see also. Practical examples are provided to illustrate their application in quantum algorithm design.The catalog aims to assist quantum algorithm designers by offering insights into the strengths and limitations of different ansatzes, thereby facilitating decision-making for specific tasks.