Automatic oracle generation in Microsoft's Quantum Development Kit using QIR and LLVM passes

TL;DR

This paper presents a method for automatically generating quantum oracles from classical functions in Microsoft's Quantum Development Kit by leveraging LLVM passes and QIR, enabling higher-level quantum algorithm descriptions.

Contribution

It introduces LLVM passes that convert classical Q# functions into QIR code, facilitating automatic and optimized quantum oracle generation.

Findings

Enables automatic oracle generation from classical functions

Supports higher-level quantum algorithm descriptions

Uses state-of-the-art logic optimization techniques

Abstract

Automatic oracle generation techniques can find optimized quantum circuits for classical components in quantum algorithms. However, most implementations of oracle generation techniques require that the classical component is expressed in terms of a conventional logic representation such as logic networks, truth tables, or decision diagrams. We implemented LLVM passes that can automatically generate QIR functions representing classical Q# functions into QIR code implementing such functions quantumly. We are using state-of-the-art logic optimization and oracle generation techniques based on XOR-AND graphs for this purpose. This enables not only a more natural description of the quantum algorithm on a higher level of abstraction, but also enables technology-dependent or application-specific generation of the oracles.