Block-encodings as programming abstractions: The Eclipse Qrisp BlockEncoding Interface
This work provides a practical software tool that lowers the barrier for implementing block-encoding-based quantum algorithms, benefiting researchers and developers in quantum computing.
The paper introduces the BlockEncoding interface within the Eclipse Qrisp framework, making block-encodings a high-level programming abstraction for quantum algorithms. It demonstrates how this interface simplifies the implementation and resource estimation of advanced quantum protocols like QSVT, QSP, and the CKS algorithm.
Block-encoding is a foundational technique in modern quantum algorithms, enabling the implementation of non-unitary operations by embedding them into larger unitary matrices. While theoretically powerful and essential for advanced protocols like Quantum Singular Value Transformation (QSVT) and Quantum Signal Processing (QSP), the generation of compilable implementations of block-encodings poses a formidable challenge. This work presents the BlockEncoding interface within the Eclipse Qrisp framework, establishing block-encodings as a high-level programming abstraction accessible to a broad scientific audience. Serving as both a technical framework introduction and a hands-on tutorial, this paper explicitly details key underlying concepts abstracted away by the interface, such as block-encoding construction and qubitization, and their practical integration into methods like the Childs-Kothari-Somma (CKS) algorithm. We outline the interface's software architecture, encompassing constructors, core utilities, arithmetic composition, and algorithmic applications such as matrix inversion, polynomial filtering, and Hamiltonian simulation. Through code examples, we demonstrate how this interface simplifies both the practical realization of advanced quantum algorithms and their associated resource estimation.