Quantum Circuits and Quantum Information Processing Fundamentals

Ivan B. Djordjević

Ivan B. Djordjević

Stefanie Barz

Abstract Quantum physics has revolutionized our understanding of information processing and enables computational speed-ups that are unattainable using classical computers. This tutorial reviews the fundamental tools of photonic quantum information processing. The basics of theoretical quantum computing are presented and the quantum circuit model as well as measurement-based models of quantum computing are introduced. Furthermore, it is shown how these concepts can be implemented experimentally using photonic qubits, where information is encoded in the photons’ polarization.

Elloá B. Guedes, Francisco de Assis, Rex A. C. Medeiros

Jincheng Zhang

Quantum circuits are fundamental building blocks for quantum information processing, and their design and optimization are crucial for achieving desired outcomes. This paper introduces a novel framework, "Quantum Adaptive Circuit Design" (QACD), leveraging the unique properties of quantum entanglement to dynamically adjust circuit parameters during the design process. The core mechanism involves utilizing entangled qubit states to represent and manipulate circuit states, enabling a continuous optimization loop that adapts to the system's performance. This approach offers a significant advancement over traditional static circuit design methodologies, potentially leading to improved qubit fidelity, reduced error rates, and enhanced overall quantum circuit performance. We present a theoretical framework and preliminary experimental results demonstrating the effectiveness of QACD in optimizing quantum circuit parameters.

Zhihao Wu, Junjie Wu, Anqi Huang

Abstract Simulators for photonic quantum information processing (PQIP) experiments are essentially different with currently available quantum-circuit simulators. In PQIP experiments, photons are usually encoded by multiple degrees of freedom, some of which are multi-level or even infinite-level. Moreover, the evolution of indistinguishable photons cannot be described elegantly by the model used in quantum-circuit simulators. A simulator focusing on PQIP experiments is urgently needed, as it plays an important role in PQIP experiments designing and verification. We developed PhotoniQLAB, an object-oriented framework designed for simulating PQIP experiments, which provides a virtual-lab user experience. The core simulation unit is a computer algebraic system based on the second quantization method. PhotoniQLAB only requires users to enter the structure information of a target PQIP experiment to conduct a simulation, as it can understand the topological structure by itself. The mathematical foundation and technical details of PhotoniQLAB are discussed in the paper. The performance of PhotoniQLAB, which is analyzed and used to simulate several experimental schemes in this paper, has been shown to be efficient enough for near-term PQIP experiments. PhotoniQLAB shows its flexibility and universality, through simulating more than 60 existing PQIP experiments in published papers. We believe that PhotoniQLAB will become a fundamental PQIP software infrastructure facilitating the analyses and designs of PQIP experiments.