What is a quantum computer, and how do we build one?

The DiVincenzo criteria for implementing a quantum computer have been seminal in focussing both experimental and theoretical research in quantum information processing. These criteria were formulated specifically for the circuit model of quantum computing. However, several new models for quantum computing (paradigms) have been proposed that do not seem to fit the criteria well. The question is therefore what are the general criteria for implementing quantum computers. To this end, a formal operational definition of a quantum computer is introduced. It is then shown that according to this definition a device is a quantum computer if it obeys the following four criteria: Any quantum computer must (1) have a quantum memory; (2) facilitate a controlled quantum evolution of the quantum memory; (3) include a method for cooling the quantum memory; and (4) provide a readout mechanism for subsets of the quantum memory. The criteria are met when the device is scalable and operates fault-tolerantly. We discuss various existing quantum computing paradigms, and how they fit within this framework. Finally, we lay out a roadmap for selecting an avenue towards building a quantum computer. This is summarized in a decision tree intended to help experimentalists determine the most natural paradigm given a particular physical implementation

Combining paraconsistent and dynamic logic for Qiskit

Dissertação de mestrado integrado em Engenharia FísicaThis dissertation introduces a logic aimed at combining dynamic logic and paraconsistent logic for application to the quantum domain, to reason about quantum phase properties: Paraconsistent Phased Logic Of Quantum Programs (PhLQP◦ ). In the design PhLQP◦ , firstly the dynamic was built first, Phased Logic Of Quantum Programs (PhLQP). PhLQP is itself a dynamic logic capable of dealing with quantum phase properties, quantum measurements, unitary evolutions, and entanglements in compound systems , since it is a redesign of the already existing Logic Of Quantum Programs (LQP), [14], over a representation of quantum states restricted to a space B equipped with only two computational basis, standard and Hadamard. As instances of applications of the logic PhLQP, there is a formal proof of the correctness of the Quantum Teleportation Protocol, of the 2-party and 4-party of the Quantum Leader Election (QLE) protocol, and of the Quantum Fourier Transform (QFT) operator for 1, 2 and 3 qubits . On a second stage, PhLQP was extended with the connective ◦ known as the consistency operator, a typical connective of the paraconsistent logics Logics of Formal Inconsistency (LFIs), [8, 21, 22]. The definition of consistent quantum state and a set of proper para consistent axioms for the quantum domain, Fundamental Paraconsistent Quantum Axioms (FParQAxs), were provided. An example of application of PhLQP◦ is the possibility of express and prove correctness of the universal quantum gate, the Deustch gate.Esta dissertação introduz uma lógica que tem como objectivo combinar lógica dinâmica e lógica paraconsistente com aplicação no domínio quântico, assim como expressar propriedades relacionadas com fases quânticas: PhLQP◦. No projetar da PhLQP◦, primeiramente concebeu-se a sua componente dinâmica, PhLQP. PhLQP por si só é uma lógica capaz de lidar com propriedades de fases quânticas, evoluções unitárias, e entrelaçamento em sistemas compostos, uma vez que é um redesenhar da já existente LQP, [14], sobre uma representação de estados quânticos restrita a um espaço B munido de apenas duas bases computacionais, standard e Hadamard. Como instâncias de aplicação da lógica PhLQP, há uma prova formal para a correção do protocolo de Teletransporte Quântico, para o protocolo QLE para uma party quer de 2 quer de 4 agentes, e para o operador de QFT de 1, 2, e 3 qubits. Numa segunda fase, PhLQP é extendida com a conectiva ◦, conhecida como operador de consistência, uma conectiva característica das LFIs, [8, 21, 22]. E a partir desta conectiva a definição de estado quântico consistente é um conjunto de axiomas paraconsistentes próprios para o domínio quântico, FParQAxs. Um exemplo de aplicação da PhLQP◦ é a possibilidade de expressar e permitir correção para o comportamento da gate quântica universal, a Deutsch-gate

Computer Aided Verification

This open access two-volume set LNCS 13371 and 13372 constitutes the refereed proceedings of the 34rd International Conference on Computer Aided Verification, CAV 2022, which was held in Haifa, Israel, in August 2022. The 40 full papers presented together with 9 tool papers and 2 case studies were carefully reviewed and selected from 209 submissions. The papers were organized in the following topical sections: Part I: Invited papers; formal methods for probabilistic programs; formal methods for neural networks; software Verification and model checking; hyperproperties and security; formal methods for hardware, cyber-physical, and hybrid systems. Part II: Probabilistic techniques; automata and logic; deductive verification and decision procedures; machine learning; synthesis and concurrency. This is an open access book

Programming Languages and Systems

This open access book constitutes the proceedings of the 30th European Symposium on Programming, ESOP 2021, which was held during March 27 until April 1, 2021, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2021. The conference was planned to take place in Luxembourg and changed to an online format due to the COVID-19 pandemic. The 24 papers included in this volume were carefully reviewed and selected from 79 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Dagstuhl News January - December 2006

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic