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BIBLIOTECAS DA UFG 18
CAMPUS CIDADE OCIDENTAL 0
CAMPUS GOIÁS ( CG) 207
REGIÃO METROPOLITANA DE GOIÂNIA (RMG) 20498
Campus Samambaia, Campus Colemar Natal e Silva, Campus Aparecida de Goiânia.

Submissões Recentes

Asymmetry and irreversibility in the Lipkin-Meshkov-Glick model in the dynamical critical regime
(2026) Nascimento, Andesson Brito; Céleri, Lucas Chibebe
Symmetries play a central role in both equilibrium and nonequilibrium phase transitions, yet their quantitative characterization in dynamical quantum phase transitions (DQPTs) remains an open challenge. In this work, we establish a direct connection between the symmetry properties of a many-body model and measures of quantum asymmetry, showing that asymmetry monotones provide a robust and physically transparent indicator of dynamical quantum criticality. Focusing on the quenched Lipkin-Meshkov-Glick model, we demonstrate that asymmetry measures associated with collective spin generators faithfully capture the onset of DQPTs, reflecting the dynamical restoration or breaking of underlying symmetries. Remarkably, the time-averaged asymmetry exhibits clear signatures of the dynamical critical point, in close correspondence with both the dynamical order parameter and the behavior of entropy production. We further uncover a quantitative link between asymmetry generation and thermodynamic irreversibility, showing that peaks in asymmetry coincide with maximal entropy production across the transition. Our results position asymmetry as a unifying concept bridging symmetry, information-theoretic quantifiers, and nonequilibrium thermodynamics in DQPTs, providing a powerful framework for understanding critical dynamics beyond traditional order parameters.
Engineered Kerr nonlinearities for precise quantum control of Fock states
(2026) Damas, Gabriella Gonçalves; Diniz, Ciro Micheletti; Almeida, Norton Gomes de; Villas-Bôas, Celso Jorge; Moraes Neto, Gentil Dias de
We present a practical design framework for high-fidelity quantum control in coupled Kerr-nonlinear oscillators, directly addressing the challenge of spectral crowding. We show that systematic spectral degeneracies, which hinder selective addressing, are a direct consequence of rational Kerr-nonlinearity ratios (Math input error). Our solution is a universal architectural principle: engineer this ratio to be a complex rational value, approximating an incommensurate number to systematically eliminate parasitic resonances. Using a Magnus expansion, we derive a complete effective Hamiltonian, including all Stark-shift corrections, to accurately target transitions. We numerically validate this framework by demonstrating protocols for the deterministic synthesis of NOON states, and high-photon-number Fock states, achieving ideal fidelities exceeding Math input error. The protocols are shown to be robust against environmental decay and thermal effects. This work provides an architectural blueprint for bosonic processors in circuit quantum electrodynamics and establishes foundational principles that could inform future designs of multimode quantum systems.
From superradiance to collective electromagnetically induced transparency in three-level ensembles
(2026) Araujo, Hugo Sanchez de; Silva, Luís Felipe Alves da; Ponte, Mickel Abreu de; Almeida, Norton Gomes de
We investigate the collective dynamics of a three-level ensemble under the Dicke limit, revealing a unified connection between superradiant emission and electromagnetically induced transparency (EIT). Our results show that the transient superradiant burst exhibits the expected peak intensity scaling Math input error, with a universal finite-size correction Math input error that governs the apparent scaling exponent in realistic ensembles. In the stationary regime, collective broadening modifies the EIT response: although it typically enhances absorption, it counterintuitively increases the group velocity, leading to a relative scaling Math input error, even while Math input error. This effect suggests that cooperative interactions fundamentally limit the achievable slow-light delay in dense media. To achieve these results, we derive a representative-atom master equation that quantitatively reproduces both the superradiant and EIT regimes, in excellent agreement with the exact symmetric-subspace dynamics and correctly incorporating collective feedback and Math input error-dependent broadening. This unified framework bridges transient superradiant emission and steady-state quantum interference, with direct implications for slow light, quantum memories, and precision metrology.
Controlling oxygen vacancies in BiFeO3 thin films via pyrolysis temperature and O2 annealing
(2026) Reis, Saulo Portes dos; Teixeira, Marco Antonio de Mello; Minussi, Fernando Brondani; Hortiguela Gallo, Maria Jesus; Otero Irurueta, Gonzalo Guillermo; Bufaiçal, Leandro Felix de Sousa; Araujo, Eudes Borges de
Bismuth ferrite (BiFeO3) is a promising material for developing the next generation of multifunctional electronic devices. However, the production of high-quality BiFeO3 thin films is compromised by the tendency for structural and electronic defects to form during synthesis, which degrades their functional properties. In this work, BiFeO3 thin films were prepared by chemical solution deposition to determine optimal conditions for minimizing oxygen vacancies and to evaluate the impact of these point defects on their physical properties. The films were pyrolyzed at 300 ◦C for 60 min and 360 ◦C for 10 min, and crystallized in air and in an O2 atmosphere, at 600 ◦C and 640 ◦C for 40 min. High oxygen vacancies were observed in films prepared at low pyrolysis temperatures and crystallized in air, whereas oxygen vacancies were minimized in the film pyrolyzed and crystallized at high temperatures in an O2 atmosphere. The oxygen vacancies markedly affected the films’ physical properties, leading to increased dielectric loss, dielectric dispersion, dc conductivity, and leakage current, with consequent degradation of photovoltaic and magnetic performance. These findings highlight the critical importance of controlling synthesis parameters to suppress oxygen vacancy formation and achieve high-quality BiFeO3 thin films.
Multivariate analysis of linear and nonlinear optical properties in purine derivatives: a predictive framework from one-photon absorption spectra
(2026) Andrade, Ian Ribeiro de; Cocca, Leandro Henrique Zucolotto
The rational design of fluorescent organic molecules is central to the development of advanced linear and nonlinear photonic materials. Purine-based compounds have emerged as promise candidates for several photonics applications due to their structural similarity to biological nucleobases synthetic versatility and favorable photophysical properties. However, their optical characterization typically generates large and complex data sets that are difficult to interpret, particularly when multiple compounds are analyzed simultaneously. Here, we apply principal component analysis (PCA) to a series of purine derivatives to systematically investigate the relationships between molecular descriptors and photophysical performance. The PCA model applied in the optical properties of the set captures 76.8% of the total variance within the first two principal components, enabling clear clustering of molecules according to their electronic structure. Importantly, by applying PCA directly to one- and two-photon absorption spectra, we achieve effective spectral deconvolution with 91.87% and 94.51%, respectively, isolating contributions associated with intensity, spectral shifts, and bandwidth. The robustness of this approach is validated through accurate spectral reconstruction. To extend the analysis toward predictive modeling, multiple linear regression (MLR) was employed to correlate PCA-derived features from one-photon absorption data with the transition dipole moment (μ01). The proposed PCA-MLR framework effectively captures the intrinsic relationships within the spectra of the studied group, minimizing the need for extensive experimental trials. The resulting model exhibits excellent predictive performance (R2 = 0.9728) and accurately estimating the μ01 = 7.07D of an external validation molecule with a deviation of approximately 2.5%. Overall, this PCA-MLR framework provides a powerful and efficient strategy for interpreting complex photophysical data sets and accelerating the design and optimization of organic molecules for linear and nonlinear photonic applications.