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Sobre

Sobre

Sou Professor Catedrático no Departamento de Informática da Universidade do Minho, e investigador sénior no High Assurance Software Laboratory (HASLab INESC TEC). Desde Outubro de 2016, sou Director Adunto da UNU-EGOV, a Operational Unit on Policy-driven Electronic Governance da Universidade das Nações Unidas (egov.unu.edu).

Os meus interesses de investigação estão focados na semântica do fenómeno computacional e no desenvolvimento de cálculos de programs aplicados à compreensão de sistemas e à concepção de software. Estou particularmente interessado em teoria das coálgebras e raciocínio coindutivo, assim como em lógicas modais e híbridas.

Nos últimos anos coordenei quatro projectos de investigação a nível nacional, parcerias bilaterais com o Brasil e China, e fui coordenador no lado português de uma rede ALFA (Europa - América Latina) para formação doutoral. Sou autor de cinco capítulos de livro,  25 artigos em revistas indexadas, e mais de 60 artigos em conferências internacionais. Tendo lecionado em curso de Mestrado e Programas Doutorais nas Universidades de Bristol (Reino Unido), Tartu (Estónia), e Pequim (China), orientei igualmente diversos projectos de doutoramento (seis concluídos; quatro em curso). Um dos meus orientando,  Alexandre Madeira, recebeu o Prémio Científico IBM para 2013, o mais importante prémio científico em Informática em Portugal.

Integrei, por nomeação reitoral,  o grupo que concebeu e implementou o "Joint Doctoral Programme in Computer Science of the Universities of Minho, Aveiro, and Porto" (MAP-i), tendo mais tarde servido como seu director. Sou membro do IFIP WG1.3 (Foundations of System Specification), e, desde Janeiro 2019, coordenador do IFIP Tecnhical Committee TC1 on Foundations of Computer Science.

Actualmente coordeno o Quantum Software Engineering Research Group no INL, o International Iberian Nanotechnology Laboratoryf.

Tópicos
de interesse
Detalhes

Detalhes

  • Nome

    Luís Soares Barbosa
  • Cargo

    Investigador Coordenador
  • Desde

    01 novembro 2011
003
Publicações

2025

Specification of paraconsistent transition systems, revisited

Autores
Cunha, J; Madeira, A; Barbosa, LS;

Publicação
SCIENCE OF COMPUTER PROGRAMMING

Abstract
The need for more flexible and robust models to reason about systems in the presence of conflicting information is becoming more and more relevant in different contexts. This has prompted the introduction of paraconsistent transition systems, where transitions are characterized by two pairs of weights: one representing the evidence that the transition effectively occurs and the other its absence. Such a pair of weights can express scenarios of vagueness and inconsistency. . This paper establishes a foundation for a compositional and structured specification approach of paraconsistent transition systems, framed as paraconsistent institution. . The proposed methodology follows the stepwise implementation process outlined by Sannella and Tarlecki.

2024

On Quantum Natural Policy Gradients

Autores
Sequeira, A; Santos, LP; Barbosa, LS;

Publicação
IEEE TRANSACTIONS ON QUANTUM ENGINEERING

Abstract
This article delves into the role of the quantum Fisher information matrix (FIM) in enhancing the performance of parameterized quantum circuit (PQC)-based reinforcement learning agents. While previous studies have highlighted the effectiveness of PQC-based policies preconditioned with the quantum FIM in contextual bandits, its impact in broader reinforcement learning contexts, such as Markov decision processes, is less clear. Through a detailed analysis of L & ouml;wner inequalities between quantum and classical FIMs, this study uncovers the nuanced distinctions and implications of using each type of FIM. Our results indicate that a PQC-based agent using the quantum FIM without additional insights typically incurs a larger approximation error and does not guarantee improved performance compared to the classical FIM. Empirical evaluations in classic control benchmarks suggest even though quantum FIM preconditioning outperforms standard gradient ascent, in general, it is not superior to classical FIM preconditioning.

2024

Digital quantum simulation of non-perturbative dynamics of open systems with orthogonal polynomials

Autores
Guimaraes, JD; Vasilevskiy, MI; Barbosa, LS;

Publicação
QUANTUM

Abstract
Classical non-perturbative simulations of open quantum systems' dynamics face several scalability problems, namely, exponential scaling of the computational effort as a function of either the time length of the simulation or the size of the open system. In this work, we propose the use of the Time Evolving Density operator with Orthogonal Polynomials Algorithm (TEDOPA) on a quantum computer, which we term as Quantum TEDOPA (Q-TEDOPA), to simulate nonperturbative dynamics of open quantum systems linearly coupled to a bosonic environment (continuous phonon bath). By performing a change of basis of the Hamiltonian, the TEDOPA yields a chain of harmonic oscillators with only local nearestneighbour interactions, making this algorithm suitable for implementation on quantum devices with limited qubit connectivity such as superconducting quantum processors. We analyse in detail the implementation of the TEDOPA on a quantum device and show that exponential scalings of computational resources can potentially be avoided for time-evolution simulations of the systems considered in this work. We applied the proposed method to the simulation of the exciton transport between two light-harvesting molecules in the regime of moderate coupling strength to a non-Markovian harmonic oscillator environment on an IBMQ device. Applications of the Q-TEDOPA span problems which can not be solved by perturbation techniques belonging to different areas, such as the dynamics of quantum biological systems and strongly correlated condensed matter systems.

2024

Secure two-party computation via measurement-based quantum computing

Autores
Rahmani, Z; Pinto, AHMN; Barbosa, LMDCS;

Publicação
QUANTUM INFORMATION PROCESSING

Abstract
Secure multiparty computation (SMC) provides collaboration among multiple parties, ensuring the confidentiality of their private information. However, classical SMC implementations encounter significant security and efficiency challenges. Resorting to the entangled Greenberger-Horne-Zeilinger (GHZ) state, we propose a quantum-based two-party protocol to compute binary Boolean functions, with the help of a third party. We exploit a technique in which a random Z-phase rotation on the GHZ state is performed to achieve higher security. The security and complexity analyses demonstrate the feasibility and improved security of our scheme compared to other SMC Boolean function computation methods. Additionally, we implemented the proposed protocol on the IBM QisKit and found consistent outcomes that validate the protocol's correctness.

2024

Quantum advantage in temporally flat measurement-based quantum computation

Autores
de Oliveira, M; Barbosa, LS; Galvao, EF;

Publicação
QUANTUM

Abstract
Several classes of quantum circuits have been shown to provide a quantum computational advantage under certain assumptions. The study of ever more restricted classes of quantum circuits capable of quantum advantage is motivated by possible simplifications in experimental demonstrations. In this paper we study the efficiency of measurement-based quantum computation with a completely flat temporal ordering of measurements. We propose new constructions for the deterministic computation of arbitrary Boolean functions, drawing on correlations present in multi-qubit Greenberger, Horne, and Zeilinger (GHZ) states. We characterize the necessary measurement complexity using the Clifford hierarchy, and also generally decrease the number of qubits needed with respect to previous constructions. In particular, we identify a family of Boolean functions for which deterministic evaluation using non-adaptive MBQC is possible, featuring quantum advantage in width and number of gates with respect to classical circuits.

Teses
supervisionadas

2023

Timing Constraints in Quantum Programming Languages

Autor
Vítor Emanuel Gonçalves Fernandes

Instituição
UM

2023

Time-structure in measurement-based quantum computation

Autor
Michael de Oliveira

Instituição
UM

2023

Continuous-time Quantum Walks

Autor
Jaime Pereira Santos

Instituição
UM

2022

Foundations for quantum algorithms and complexity

Autor
Carlos Eduardo Teixeira Tavares

Instituição
UM

2022

Weighted Computations: semantics and program logics

Autor
Leandro Rafael Moreira Gomes

Instituição
UM