Quantum Parrondo's game with random strategies

We present a quantum implementation of Parrondo's game with randomly switched strategies using 1) a quantum walk as a source of ``randomness'' and 2) a completely positive (CP) map as a randomized evolution. The game exhibits the same paradox as in the classical setting where a combination of two losing strategies might result in a winning strategy. We show that the CP-map scheme leads to significantly lower net gain than the quantum walk scheme

Towards a taxonomy for reversible computation approaches

Reversible computation is a paradigm allowing computation to proceed not only in the usual, forward direction, but also backwards. Reversible computation has been studied in a variety of models, including sequential and concurrent programming languages, automata, process calculi, Turing machines, circuits, Petri nets, event structures, term rewriting, quantum computing, and others. Also, it has found applications in areas as different as low-power computing, debugging, simulation, robotics, database design, and biochemical modeling. Thus, while the broad idea of reversible computation is the same in all the areas, it has been interpreted and adapted to fit the various settings. The existing notions of reversible computation however have never been compared and categorized in detail. This work aims at being a first stepping stone towards a taxonomy of the approaches that co-exist under the term re- versible computation. We hope that such a work will shed light on the relation among the various approaches

An experimental proposal for revealing contextuality in almost all qutrit states

10.1038/srep02706Scientific Reports3

Bits and qubits

Quantum computing is an interdisciplinary field of research, and it is natural that many people starting in this area should feel uncomfortable with the fundamentals of either computer science or physics. In this chapter, we briefly review the basic concepts necessary to follow the rest of the book734CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão temNão temNão temWe are grateful to our colleagues and students from the Federal University of Rio de Janeiro (UFRJ, Brazil), the National Laboratory for Scientific Computing (LNCC, Brazil), and the University of Campinas (UNICAMP, Brazil) for several important discussions and interesting ideas. We acknowledge CAPES, CNPq, FAPERJ, and FAPESP—Brazilian funding agencies—for the financial support to our research projects. We also thank the Brazilian Society of Computational and Applied Mathematics (SBMAC) for the opportunity to give a course on this subject that resulted in the first version of this monograph in Portuguese (http://www.sbmac.org.br/arquivos/notas/livro_08.pdf), which in turn evolved from our earliest tutorials (in arXiv quant-ph/0301079 and quant-ph/0303175