A Quanta é um grupo de pesquisa em Óptica e Informação Quântica da Universidade Federal de São Carlos (UFSCar).
Unimos pesquisa de ponta e exploramos os limites da interação entre luz e matéria no mundo quântico, transformando conceitos como superposição e emaranhamento em soluções inovadoras que conectam ciência de ponta à indústria e aos serviços.
Transformamos conhecimento científico em inovação estratégica, conectando a universidade à indústria e ao setor de serviços, e fortalecendo o protagonismo do Brasil no cenário global da tecnologia quântica.
Celso J. Villas-Boas, Carlos E. Máximo, Paulo J. Paulino, Romain P. Bachelard, Gerhard Rempe
Physical Review Letters134(13): 133603(2025)
Classical theory asserts that several electromagnetic waves cannot interact with matter if they interfere destructively to zero, whereas quantum mechanics predicts a nontrivial light-matter dynamics even when the average electric......
Gubio G. de Lima, Gustavo Café de Miranda, Tiago de S. Farias
Revista Brasileira de Ensino de Física48: e20250183(2026)
Resumo As técnicas de aprendizado de máquina emergiram no contexto científico e se desenvolveram como ferramentas poderosas para enfrentar uma ampla gama de desafios na sociedade. A integração dessas técnicas......
O. P. de Sá Neto, D. Z. Rossatto, Amjad Sohail, M. C. de Oliveira
Europhysics Letters153(1): 18001(2026)
The interaction between photons and phonons mediated by a third medium has significant potential for various applications in quantum information technology. Inspired by experimental investigations obtained on hybrid circuits, we......
Gubio Gomes de Lima, Tiago de S. Farias, Alexandre C. Ricardo, Celso Jorge Villa Boas
Quantum Machine Intelligence8(1): 20(2026)
TL;DR
QNNs excelled at approximating the sinusoidal function, achieving errors up to seven orders of magnitude lower than their classical counterparts, emphasizing that QNNs are highly effective for certain tasks but not universally superior.
In special relativity, particle trajectories, whether mass-bearing or not, can be traced on the Minkowski spacetime manifold in (3+1)D. Meantime, in quantum mechanics, trajectories in the phase space are not......
Bright and Dark States of Light: The Quantum Origin of Classical Interference.
Physical Review Letters134 (13) (2025)
Resumo
Classical theory asserts that several electromagnetic waves cannot interact with matter if they interfere destructively to zero, whereas quantum mechanics predicts a nontrivial light-matter dynamics even when the average electric field vanishes. Here, we show that in quantum optics, classical interference emerges from collective bright and dark states of light, i.e., particular cases of two-mode binomial states, which are entangled superpositions of multimode photon-number states. This makes it possible to explain wave interference using the particle description of light and the superposition principle for linear systems only. It also sheds new light on an old debate concerning the origin of complementarity.
Resumo As técnicas de aprendizado de máquina emergiram no contexto científico e se desenvolveram como ferramentas poderosas para enfrentar uma ampla gama de desafios na sociedade. A integração dessas técnicas com a física tem conduzido a abordagens inovadoras na compreensão, controle e simulação de fenômenos físicos. Este artigo visa proporcionar uma introdução prática às redes neurais e seus conceitos fundamentais, destacando perspectivas recentes dos avanços na interseção entre modelos de aprendizado de máquina e sistemas físicos. Além disso, apresentamos um material prático para orientar o leitor em seus primeiros passos na aplicação de redes neurais para resolver problemas físicos. Como exemplo ilustrativo, fornecemos quatro aplicações de complexidades crescentes para o problema de um pêndulo simples, a saber: fit de parâmetros da Equação Diferencial Ordinária (EDO) do pêndulo para aproximação de ângulo pequeno; Physics Informed Neural Networks (PINNs) para encontrar soluções da EDO do pêndulo em ângulo pequeno; Autoencoders em conjunto de dados de imagens do pêndulo para estimação de dimensionalidade do espaço de parâmetros do problema físico; uso de arquiteturas Sparse Identification of Non-Linear Dynamics (SINDy) para descoberta de modelos e expressões analíticas para o problema do pêndulo não linear (ângulos grandes).
Exploring the nature of phonon-qubit-photon coupling in a hybrid circuit
Europhysics Letters153 (1) 18001 (2026)
Resumo
The interaction between photons and phonons mediated by a third medium has significant potential for various applications in quantum information technology. Inspired by experimental investigations obtained on hybrid circuits, we aimed to develop a comprehensive theory for analytically calculating the transmission and reflection spectra, as well as obtaining eigenenergies of the circuits associated with this interaction. When analyzing the transmission spectra, we observed an intriguing correlation between the eigenenergies and the spectral peaks. This observation suggests the possibility of a deeper understanding of the stationary states involved in this unique hybrid circuit. Through this analysis, we aim not only to describe the observed phenomena but also to provide valuable insights for quantum technology.
Assessing the advantages and limitations of quantum neural networks in regression tasks
Quantum Machine Intelligence8 (1) (2026)
Resumo
The development of quantum neural networks (QNNs) has attracted considerable attention due to their potential to surpass classical models in certain machine learning tasks. Nonetheless, it remains unclear under which conditions QNNs provide concrete benefits over classical neural networks (CNNs). This study addresses this question by performing both qualitative and quantitative analyses of classical and quantum models applied to regression problems, using two target functions with contrasting properties. Additionally, the work explores the methodological difficulties inherent in making fair comparisons between QNNs and CNNs. The findings reveal a distinct advantage of QNNs in a specific quantum machine learning context. In particular, QNNs excelled at approximating the sinusoidal function, achieving errors up to seven orders of magnitude lower than their classical counterparts. However, their performance was limited in other cases, emphasizing that QNNs are highly effective for certain tasks but not universally superior. These results reinforce the principles of the “No Free Lunch” theorem, highlighting that no single model outperforms all others across every problem domain.
Disentanglement of a Bipartite System Portrayed in a (3+1)D Compact Minkowski Manifold: Quadridistances and Quadrispeeds
Physics7 (4) 45 (2025)
Resumo
In special relativity, particle trajectories, whether mass-bearing or not, can be traced on the Minkowski spacetime manifold in (3+1)D. Meantime, in quantum mechanics, trajectories in the phase space are not strictly outlined because coordinate and linear momentum cannot be measured simultaneously with arbitrary precision since they do not commute within the Hilbert space formalism. However, from the density matrix representing a quantum system, the extracted information still produces an imperative description of its properties and, furthermore, by appropriately reordering the matrix entries, additional information can be obtained from the same content. Adhering to this line of work, the paper investigates the definition and the meaning of velocity and speed in a typical quantum phenomenon, the disentanglement for a bipartite system when dynamical evolution is displayed in a (3+1)D pseudo-spacetime whose coordinates are constructed from combinations of entries to the density matrix. The formalism is based on the definition of a Minkowski manifold with compact support, where trajectories are defined following the same reasoning and formalism present in the Minkowski manifold of special relativity. The space-like and time-like regions acquire different significations referred to entangled-like and separable-like, respectively. The definition and the sense of speed and velocities of disentanglement follow naturally from the formalism. Depending on the dynamics of the physical state of the system, trajectories may meander between regions of entanglement and separability in the space of new coordinates defined on the Minkowski manifold.
O 1º Workshop do Quanta foi realizado com grande sucesso, reunindo mais de 50 participantes entre estudantes de graduação, pós-graduação, professores e pesquisadores. Ao todo,...
