Abstract Quantum computing systems promise to increase the capabilities for solving problems which classical computers cannot handle adequately, such as integers factorization. In this paper, we present a formal modeling and verification approach for optical quantum circuits, where we build a rich library of optical quantum gates and develop a proof strategy in higher-order logic to reason about optical quantum circuits automatically. The constructed library contains a variety of quantum gates ranging from 1-qubit to 3-qubit gates that are sufficient to model most existing quantum circuits. As real world applications, we present the formal analysis of several quantum circuits including quantum full adders and the Grover’s oracle circuits, for which we have proved the behavioral correctness and calculated the operational success rate, which has never been provided in the literature. We show through several case studies the efficiency of the proposed framework in terms of the scalability and modularity.
Abstract Quantum computing systems promise to increase the capabilities for solving problems which classical computers cannot handle adequately, such as integers factorization. In this paper, we present a formal modeling and verification approach for optical quantum circuits, where we build a rich library of optical quantum gates and develop a proof strategy in higher-order logic to reason about optical quantum circuits automatically. The constructed library contains a variety of quantum gates ranging from 1-qubit to 3-qubit gates that are sufficient to model most existing quantum circuits. As real world applications, we present the formal analysis of several quantum circuits including quantum full adders and the Grover’s oracle circuits, for which we have proved the behavioral correctness and calculated the operational success rate, which has never been provided in the literature. We show through several case studies the efficiency of the proposed framework in terms of the scalability and modularity.
Quantum mechanics based computing systems are expected to have high capabilities and are considered good candidates to replace classical cryptography and supercomputing systems. Among many implementations, quantum optics systems provide a promising platform to implement universal quantum computers, since they link quantum computation and quantum communication in the same framework. Recently, several quantum gates, circuits, and protocols have been experimentally realized using optics. Despite the fact that big advances in building the physical quantum computers were achieved, there are no currently available industrial computer aided tools that can perform the modeling, analysis, and verification of optical quantum computing systems. In this thesis, we tackle the idea of design automation for quantum circuits, where we use a sound language, higher order logic, to model and reason about quantum circuits formally. In particular, we propose a framework for the hierarchical modeling and automated verification of quantum computing circuits. The modeling approach captures quantum models built hierarchically from quantum gates, which models are readily available in a library. The analysis and verification of composed circuits is done seamlessly based on dedicated mathematical foundations formalized in the theorem prover. \nSpecifically, the tensor product and linear projection are used to extract the quantum circuit outputs. Subsequently, a rich library of quantum gates which includes 1-qubit, 2-qubit, and 3-qubit gates is formalized. In order to automate the analysis process, we developed a decision procedure to eliminate the need of user guidance throughout the formal proofs. To demonstrate the effectiveness of the proposed framework, we conduct the formal analysis of a benchmark of quantum circuits including the Shor's integer factorization algorithm, the Grover's oracle, and the quantum full adder.
At the beginning of the last century, the theory of quantum optics arose and led to a revolution in physics, since it allowed the interpretation of many unknown phenomena and the development of numerous powerful, cutting edge engineering applications, \nsuch as high precision laser technology. The analysis and verification of such applications and systems, however, are very complicated. Moreover, traditional analysis tools, e.g., simulation, numerical methods, computer algebra systems, and paper-and-pencil approaches are not well suited for quantum systems. In the last decade, a new emerging verification technique, called formal methods, became common among engineering domains, and has proven to be effective as an analysis tool. Formal methods \nconsist in the development of mathematical models of the system subject for analysis, and deriving computer-aided mathematical proofs. In this thesis, we propose a framework for the analysis of quantum optics based on formal methods, in particular theorem proving. The framework aims at implementing necessary quantum mechanics and optics concepts and theorems that facilitate the modelling of quantum optical devices and circuits, and then reason about them formally. To this end, the framework \nconsists of three major libraries: 1) Mathematical foundations, which mainly contain the theory of complex-valued-function linear spaces, 2) Quantum mechanics, which develops the general rules of quantum physics, and 3) Quantum Optics, which \nspecializes these rules for light beams and implements all related concepts, e.g., light coherence which is typically emitted by laser sources. On top of these theoretical foundations, we build a library of formal models of a number of optical devices commonly \nused in quantum circuits, including, beam splitters, light displacers, and light phase shifters. Using the proposed framework, we have been able to formally verify common quantum optical computing circuits, namely the Flip gate, CNOT gate, and Mach-Zehnder interferometer.
Quantum computing uses the laws of quantum mechanics to perform computation. Information is stored in qubits and processed using quantum gates arranged as quantum circuits. As quantum hardware grows in size and complexity, verifying these systems becomes increasingly difficult. Traditional verification methods do not scale well and quickly become computationally infeasible. This creates a strong need for more powerful and scalable verification techniques. Formal methods provide a potential solution to this problem. Techniques such as theorem proving, model checking, and symbolic reasoning offer mathematically rigorous ways to verify correctness, equivalence, and implementation. They also help detect design errors early in the development process. This review examines how formal methods are applied to quantum circuit verification. It focuses on barrier certificates, abstract interpretation, model checking, theorem proving, and emerging hybrid approaches. The review discusses both the theoretical foundations and practical applications of these techniques. Their strengths and limitations are analysed through representative case studies. Finally, the review highlights open challenges and identifies promising directions for future research. An extensive set of references is included to support further study and exploration.
Grover's algorithm relies on the superposition and interference of quantum mechanics, which is more efficient than classical computing in specific tasks such as searching an unsorted database. Due to the high complexity of quantum mechanics, the correctness of quantum algorithms is difficult to guarantee through traditional simulation methods. By contrast, the fundamental concepts and mathematical structure of Grover's algorithm can be formalized into logical expressions and verified by higher-order logical reasoning. In this paper, we formally model and verify Grover's algorithm in the HOL Light theorem prover. We focus on proving key properties such as the unitarity of its oracle and diffusion operators, the monotonicity of the success probability with respect to the number of iterations, and an exact expression for the optimal iteration count. By analyzing a concrete application to integer factorization, we demonstrate the practicality and prospects of our work.
Quantum computing uses the laws of quantum mechanics to perform computation. Information is stored in qubits and processed using quantum gates arranged as quantum circuits. As quantum hardware grows in size and complexity, verifying these systems becomes increasingly difficult. Traditional verification methods do not scale well and quickly become computationally infeasible. This creates a strong need for more powerful and scalable verification techniques. Formal methods provide a potential solution to this problem. Techniques such as theorem proving, model checking, and symbolic reasoning offer mathematically rigorous ways to verify correctness, equivalence, and implementation. They also help detect design errors early in the development process. This review examines how formal methods are applied to quantum circuit verification. It focuses on barrier certificates, abstract interpretation, model checking, theorem proving approaches. The review discusses both the theoretical foundations and practical applications of these techniques. Their strengths and limitations are analysed through representative case studies. Finally, the review highlights open challenges and identifies promising directions for future research. An extensive set of references is included to support further study and exploration.
Quantum computing uses the laws of quantum mechanics to perform computation. Information is stored in qubits and processed using quantum gates arranged as quantum circuits. As quantum hardware grows in size and complexity, verifying these systems becomes increasingly difficult. Traditional verification methods do not scale well and quickly become computationally infeasible. This creates a strong need for more powerful and scalable verification techniques. Formal methods provide a potential solution to this problem. Techniques such as theorem proving, model checking, and symbolic reasoning offer mathematically rigorous ways to verify correctness, equivalence, and implementation. They also help detect design errors early in the development process. This study examines how formal methods are applied to quantum circuit verification. It focuses on barrier certificates, abstract interpretation, model checking, and theorem proving approaches. The study discusses both the theoretical foundations and practical applications of these techniques. Their strengths and limitations are analysed through representative case studies. Finally, the study highlights open challenges and identifies promising directions for future research. An extensive set of references is included to support further study and exploration.