Quantum Calculi—From Theory to Language Design

Abstract

In the last 20 years, several approaches to quantum programming have been introduced. In this survey, we focus on the QRAM (Quantum Random Access Machine) architectural model. We explore the twofold perspective (theoretical and concrete) of the approach and we list the main problems one has to face in quantum language design. Moreover, we propose an overview of some interesting languages and open-source platforms for quantum programming currently available. We also provide the higher-order encoding in the functional languages qPCFand IQu of the well known Deutsch-Jozsa and Simon's algorithms.Appl. Sci. 2019, 9, 5472 2 of 17 On Quantum Language Design: Main Features The Architectural ModelIn quantum software design, the choice of an architectural model is not as easy as for the classical case. This holds today and, in particular, held two decades ago, when quantum programming theory moves the first steps.In this report, we mainly focus on the so-called quantum data & classical control (qd&cc) [3,16], approach, which separates the classical and quantum parts of the computation. A classical program (ideally in execution on a classical machine) computes some "directives," sent to a hypothetical quantum device that applies them to quantum data. This idea is inspired by an architecture called Quantum Random Access Machine (QRAM), introduced by Knill [17], who noticed that the quantum circuit families [9,18], the most interesting computational model, is not enough to describe quantum algorithms. In fact, as clearly observed in Reference [19] a quantum algorithm assume an explicit "control flow" that permits to execute quantum operations, eventually measures quantum data and runs classical computation on the measured results. The following picture represents the QRAM in a simplified and intuitive way: Classical Computer Quantum Device quantum instructions feedback

Quantum Software Engineering: Landscapes and Horizons

“…Therefore, the quantum programming language plays a vital role in the life cycle of quantum software development. Several comprehensive surveys on quantum programming languages have been carried out from different perspectives [54,98,102,125,140,186,239,244,261,263,276,280,281,302,311].…”

“…They concluded the survey by pointing out some recent trends, results, and future work in the area. Another recent survey [311] is presented by Zorzi, which focuses on the QRAM (Quantum Random Access Machine) architectural model. The survey is organized from the twofold perspectives, i.e., theory and concrete, and identifies the main problems one has to face in quantum language design.…”

“…The survey is organized from the twofold perspectives, i.e., theory and concrete, and identifies the main problems one has to face in quantum language design. The survey tried to find some evidences from current researches to answer the following fundamental questions [311] regarding quantum language design and provided some possible answers to these questions.…”

“…There have been surveys related to some aspects of quantum software engineering. For example, a number of surveys [54,98,102,125,140,186,239,244,261,263,276,280,281,302,311] have been proposed for quantum programming languages, which mainly focus on the language paradigms, implementations, semantics, and tools. Surveys related to quantum software development environments [86,163,236,253] have also been proposed, from various points of view.…”

“…This section will be brief, as much of the material has been covered in the survey (or overview) papers of quantum programming languages [54,98,102,186,244,261,263,280,281,301,302,311].…”