Universality and programmability of quantum computers

Manin, Feynman, and Deutsch have viewed quantum computing as a kind of universal physical simulation procedure. Much of the writing about quantum logic circuits and quantum Turing machines has shown how these machines can simulate an arbitrary unitary transformation on a finite number of qubits. The problem of universality has been addressed most famously in a paper by Deutsch, and later by Bernstein and Vazirani as well as Kitaev and Solovay. The quantum logic circuit model, developed by Feynman and Deutsch, has been more prominent in the research literature than Deutsch's quantum Turing machines. Quantum Turing machines form a class closely related to deterministic and probabilistic Turing machines and one might hope to find a universal machine in this class. A universal machine is the basis of a notion of programmability. The extent to which universality has in fact been established by the pioneers in the field is examined and this key notion in theoretical computer science is scrutinised in quantum computing by distinguishing various connotations and concomitant results and problems.Comment: 17 pages, expands on arXiv:0705.3077v1 [quant-ph

Efficacy of hardware scheduling on current generation quantum computers

Quantum computing is a rapidly advancing field of computer science that is increasingly becoming more practical. With these devices becoming more realistic, frameworks are needed by which the hardware resources, both quantum and classical, of quantum computers can be utilized more efficiently. This research aims to fill gaps in the research examining the effectiveness of hardware scheduling on the current generation of quantum computers. A hardware scheduling strategy is implemented using the A* search algorithm for routing qubits to conform with hardware limitations, and this algorithm is tested against a wide variety of quantum programs and devices. The effectiveness of the scheduler is determined through analysis of metrics obtained from the scheduling process. This particular scheduler proved to be effective for most of the tested algorithms and efficient for some, making it useful for general purposes, though some potential sources of improvement could increase the number of algorithms it is efficient for