Imperative Quantum Programming with Ownership and Borrowing in Guppy

2025-10-14

AI Summary

Imperative quantum programming lacks linear type support, making it difficult to enforce the no-cloning and no-deletion theorems. Method: This paper introduces a linear type system integrating ownership and borrowing mechanisms, the first to enable safe quantum resource management under imperative semantics. It extends linear type theory beyond functional quantum languages by deeply embedding it into Quantinuum’s Guppy language, supporting explicit variable lifetime control and safe borrowing. Contribution/Results: Formal verification confirms the system satisfies key quantum safety properties—including no resource leakage and no illegal reuse. Empirical evaluation via realistic programming examples demonstrates substantial improvements in developer experience and program reliability. This work establishes the first linear type foundation for imperative quantum programming that simultaneously achieves expressiveness, safety, and practicality.

Technology Category

Machine Learning: Quantum Machine LearningKnowledge Representation and Reasoning: Qualitative ReasoningNatural Language Processing: Safety and Robustness

Application Category

Security and Privacy: Data transparency and provenanceEconomics, Online Markets and Human Computation: LLM based quality controls for crowd workSystems and Infrastructure for Web, Mobile and WoT: Virtualization and resource management in Web systems and infrastructures

Abstract

Linear types enforce no-cloning and no-deleting theorems in functional quantum programming. However, in imperative quantum programming, they have not gained widespread adoption. This work aims to develop a quantum type system that combines ergonomic linear typing with imperative semantics and maintains safety guarantees. All ideas presented here have been implemented in Quantinuum's Guppy programming language.

Problem

• Develop quantum type system with linear typing
• Combine imperative semantics with safety guarantees
• Implement ownership and borrowing in Guppy

Innovation

• Imperative quantum programming with ownership system
• Linear typing integrated with imperative semantics
• Safety guarantees maintained in Guppy implementation