An Exploratory Study on the Usage of Quantum Programming Languages

Tese de mestrado, Engenharia Informática, 2022, Universidade de Lisboa, Faculdade de CiênciasAs in the classical realm, the usage of quantum programming languages in quantum computing allows one to instruct a quantum computer to perform certain tasks. Although several imperative, declarative, and multi-paradigm quantum programming languages with different features and goals have been developed in the last 25 years, no study has been conducted on who, how, and what for does one use a quantum programming language. In this thesis, we first identified and described several quantum programming languages and then surveyed 251 quantum practitioners to answer several questions related to the usage of quantum programming languages. Further, an analysis of the results obtained is presented and shows that most of the quantum practitioners use the languages for research and that Qiskit (Python) is the most used one. Finally, we make recommendations for further development of quantum programming languages, such as building on top of a classical programming language, running in real quantum computers, supporting language documentation, and consulting developers’ needs

Strawberry Fields: A Software Platform for Photonic Quantum Computing

We introduce Strawberry Fields, an open-source quantum programming architecture for light-based quantum computers, and detail its key features. Built in Python, Strawberry Fields is a full-stack library for design, simulation, optimization, and quantum machine learning of continuous-variable circuits. The platform consists of three main components: (i) an API for quantum programming based on an easy-to-use language named Blackbird; (ii) a suite of three virtual quantum computer backends, built in NumPy and TensorFlow, each targeting specialized uses; and (iii) an engine which can compile Blackbird programs on various backends, including the three built-in simulators, and -- in the near future -- photonic quantum information processors. The library also contains examples of several paradigmatic algorithms, including teleportation, (Gaussian) boson sampling, instantaneous quantum polynomial, Hamiltonian simulation, and variational quantum circuit optimization.Comment: Try the Strawberry Fields Interactive website, located at http://strawberryfields.ai . Source code available at https://github.com/XanaduAI/strawberryfields. Accepted in Quantu

Towards Practical Hybrid Quantum / Classical Computing

Quantum computing is in a critical phase where theoretical schemes and protocols are now being implemented in the real world for the first time. Experimental implementations can help us solidify ideas, and can also complicate them. In the case of quantum communication protocols, we present the first experimental implementations of two entanglement-based schemes using IBM’s superconducting transmon qubit based technology. We find that the schemes are experimentally feasible with current technology, and give an idea of how much room for improvement there is before quantum technology can meet the highest theoretical expectations. These communication schemes may be fundamental components of the future quantum internet. We also present an overview of the emerging field of quantum blockchain protocols that could form a part of the quantum / classical communication structures of the future. Interaction between classical and quantum technologies can impair purely quantum designs, but can also be harnessed to enhance hybrid quantum / classical approaches. Finally, we suggest a path towards the hybridization of arbitrary code execution and verification in the hybrid quantum / classical networks of the future