Compiling quantum programs

In this paper we study a possible compiler for a high-level imperative programming language for quantum computation, the quantum Guarded-Command Language (qGCL). It is important because it liberates us from thinking of quantum algorithms at the data-flow level, in the same way as happened for standard computation a few decades ago.We make use of the normal-form approach to compiler design, introduced by Hoare, Jifeng and Sampaio. In this approach a source program is transformed, by means of algebraic manipulations, into a particular form which can be directly executed by a target machine. This entails the definition of a simple quantum hardware architecture, derived from Hoare et al.’s computing model.Our work provides a general framework for the construction of a compiler for qGCL, focusing mainly on the correctness of the design. Here we do not deal with other topics such as efficiency of compiled code, factorisation of unitary transformations and compilation of quantum data structures.