An exploratory study on the usage of quantum programming languages

As in the classical computing realm, quantum programming languages in quantum computing allow one to instruct a quantum computer to perform certain tasks. In the last 25 years, many imperative, functional, and multi-paradigm quantum programming languages with different features and goals have been developed. However, to the best of our knowledge, no study has investigated who uses quantum languages, how practitioners learn a quantum language, how experience are practitioners with quantum languages, what is the most used quantum languages, in which context practitioners use quantum languages, what are the challenges faced by quantum practitioners while using quantum languages, are program written with quantum languages tested, and what are quantum practitioners' perspectives on the variety of quantum languages and the potential need for new languages. In this paper, we first conduct a systematic survey to find and collect all quantum languages proposed in the literature and/or by organizations. Secondly, we identify and describe 37 quantum languages. Thirdly, we survey 251 quantum practitioners to answer several research questions about their quantum language usage. Fourthly, we conclude that (i) 58.2% of all practitioners are 25-44 years old, 63.0% have a master's or doctoral degree, and 86.2% have more than five years of experience using classical languages. (ii) 60.6% of practitioners learn quantum languages from the official documentation. (iii) Only 16.3% of practitioners have more than five years of experience with quantum languages. (iv) Qiskit (Python) is the most used quantum language, followed by Cirq (Python) and QDK (Q#). (v) 42.8% use quantum languages for research. (vi) Lack of documentation and usage examples are practitioners' most challenging issues. Practitioners prefer open-source quantum languages with an easy-to-learn syntax (e.g., based on an existing classical language), available documentation and examples, and an active community. (vii) 76.4% of all participants test their quantum programs, and 42.6% test them automatically. (viii) A standard quantum language, perhaps high-level language, for quantum computation could accelerate the development of quantum programs. Finally, we present a set of suggestions for developers and researchers on the development of new quantum languages or enhancement of existing ones.