This paper introduces a novel approach to quantum computation by integrating temporal logic programming with quantum state transitions. The core idea is to extend the capabilities of temporal logic programming to directly control and reason about the evolution of quantum systems. Traditional quantum programming often relies on unitary transformations and circuit descriptions, which can be complex and difficult to verify, especially for complex quantum algorithms. We propose a programming language that allows programmers to define temporal logic constraints on the desired quantum state transitions. These constraints effectively act as a higher-level specification of the quantum computation, offering improved clarity, maintainability, and verification capabilities. The system allows for precise control over quantum computations by specifying state transitions over time. This approach leverages the expressiveness of temporal logic to handle complex quantum systems and algorithms, ultimately simplifying the process of quantum algorithm design and implementation. The theoretical framework and fundamental concepts are presented, laying the groundwork for further development and exploration of this new paradigm.
The main contribution of the present paper is the introduction of a simple yet expressive hybrid-dynamic logic for describing quantum programs. This version of quantum logic can express quantum measurements and unitary evolutions of states in a natural way based on concepts advanced in (hybrid and dynamic) modal logics. We then study Horn clauses in the hybrid-dynamic quantum logic proposed, and develop a series of results that lead to an initial semantics theorem for sets of clauses that are satisfiable. This shows that a significant fragment of hybrid-dynamic quantum logic has good computational properties, and can serve as a basis for defining executable languages for specifying quantum programs. We set the foundations of logic programming in this fragment by proving a variant of Herbrand's theorem, which reduces the semantic entailment of a logic-programming query by a program to the search of a suitable substitution.
This paper introduces a novel temporal logic formalism, termed Temporal Quantum Logic (TQL), specifically tailored for representing and reasoning about the continuous evolution of quantum states. The core challenge in applying temporal logic to quantum mechanics lies in effectively capturing the inherent complexities of superposition, entanglement, and decoherence, particularly the non-commutativity of quantum operations. Existing temporal logics lack the necessary tools to accurately model these phenomena. TQL addresses this limitation by employing a multi-valued logic built upon tensor networks and process algebra concepts. This approach enables a precise and explicit representation of quantum operations, measurement outcomes, and their temporal dependencies, incorporating probabilistic semantics directly into the logic. The formalization utilizes a state representation based on tensor network contractions, allowing for the dynamic tracking of quantum state evolution over time. The logic incorporates operators that explicitly handle non-commutativity and decoherence, offering a framework for formally verifying the correctness of quantum algorithms and protocols. The key innovation is the combination of tensor network formalism with temporal logic, providing a rigorous method for describing the evolution of quantum systems and enabling a deeper understanding of their behavior. This work lays the foundation for future research in quantum verification, quantum algorithm design, and the development of quantum software.
Qubits are a great way to build a quantum computer, but a limited way to program one. We replace the usual "states and gates" formalism with a "props and ops" (propositions and operators) model in which (a) the C*-algebra of observables supplies the syntax; (b) states, viewed as linear functionals, give the semantics; and (c) a novel diagrammatic calculus unifies the two. The first part develops the basic objects of the framework, encoding consistent patterns of operator correlation, recovering Hilbert space via the GNS construction, and re-deriving the Bloch sphere as the set of all consistent correlations of operators in the Pauli algebra. We then turn to intervention, showing how measurement modifies state, proving an operator-algebraic version of the Knill-Laflamme conditions, and expressing stabilizer codes with the same diagrammatic machinery. This provides a concise, representation-agnostic account of quantum error correction. The result is a self-contained foundation in which C*-algebras, and their dual Hilbert spaces, offer a rich and universal substrate for quantum programming; forthcoming papers will build a high-level language and quantum software applications on top of this substrate.
In contrast to a classical bit, which can only take the value
0 or
1, its quantum counterpart -- a qubit -- can exist in a superposition of
0 and
1. This is a superposition of data values, naturally raising the question of whether one can superpose not only data but also programs. For example, a particular superposition of programs, known as the quantum SWITCH, has attracted much attention, and its implementations and computational advantages have been studied extensively within the physics community.
A naive way to control a program by a qubit is by means of a controlled operation. Given an operation
F, this amounts to considering an operation that behaves as
F when the control qubit is
∣1⟩, and as the identity operation when the control qubit is
∣0⟩. This idea works well when
F is a unitary operation, but it is not well-defined for a general quantum channel. By contrast, the quantum SWITCH is free from the well-definedness issue. This contrast leads to the key insight of this paper: controlled operations and the quantum SWITCH should be regarded as different kinds of quantum control mechanisms.
Building on this insight, we develop a novel quantum programming language with quantum control and measurement that can express the quantum SWITCH over quantum channels. Using a semantic analysis based on program transformations, we identify the source of the ill-behavedness of controlled operations as the \emph{correspondence problem}: a lack of coordination between the measurements performed in the then- and else-branches of quantum conditional branching. We address this problem with a linear type system that enforces alignment of the quantum operations used in the two branches, yielding a well-behaved language capable of expressing the quantum SWITCH.
Most modern (classical) programming languages support recursion. Recursion has also been successfully applied to the design of several quantum algorithms and introduced in a couple of quantum programming languages. So, it can be expected that recursion will become one of the fundamental paradigms of quantum programming. Several program logics have been developed for verification of non-recursive quantum programs. However, there are as yet no general methods for reasoning about recursive procedures in quantum computing. We fill the gap in this paper by presenting a logic for recursive quantum programs. This logic is an extension of quantum Hoare logic for quantum While-programs. The (relative) completeness of the logic is proved, and its effectiveness is shown by a running example: fixed-point Grover's search.