Papers publicados por CQOQI
https://repositorio.umayor.cl/xmlui/handle/sibum/8009
Contiene los artículos/papers publicados por CQOQI en revistas nacionales e internacionales2024-06-23T04:42:27ZA method to deconvolve stellar profiles The non-rotating line utilizing Gaussian sum approximation
https://repositorio.umayor.cl/xmlui/handle/sibum/9493
A method to deconvolve stellar profiles The non-rotating line utilizing Gaussian sum approximation
Escárate, P.; Curé, M.; Araya, I. [Univ Mayor, Ctr Opt & Informac Cuant, Vicerrectoria Invest, Chile]; Coronel, M.; Cedeño, AL.; Celedón, L.; Cavieres, J.; Agüero, JC.; Arcos, C; Cidale, LS.; Levenhagen, RS.; Pezoa, R.; Simón-Díaz, S.
Context. Currently, one of the standard procedures used to determine stellar and wind parameters of massive stars involves to comparing the observed spectral lines with a grid of synthetic lines. These synthetic lines are calculated using non-local thermodynamic equilibrium radiative transfer codes. In this standard procedure, after estimating the stellar-projected rotational speed (v sin i), all synthetic models need to be convolved using this value in order to perform the comparison with the observed line and estimate the stellar parameters.Aims. In this work, we propose a methodology to deconvolve the observed line profile to one from a non-rotating star. Thus, to perform a comparison, we will not need to convolve all the synthetic profiles, saving significant time and resources.Methods. The proposed deconvolution method is based on transforming this inverse problem into an optimization of a direct problem. We propose using a Gaussian sum approximation (GSA) to obtain the line profile without the broadening effect due to stellar rotation. After selecting the most adequate model to derive the fundamental GSA parameters, we convolved it with the known v sin i in order to obtain the profile considering the v sin i. Finally, we compared this approximated line profile directly with the observed spectrum.Results. The performance of the proposed method is analyzed using synthetic and observed lines. The results show that the proposed deconvolution method yields accurate non-rotating profiles.Conclusions. The proposed approach utilizing GSA is an accurate method to deconvolve spectral lines.
2023-08-04T00:00:00ZNonlinear optomechanical resonance entering a self-organized energy transfer pattern
https://repositorio.umayor.cl/xmlui/handle/sibum/9458
Nonlinear optomechanical resonance entering a self-organized energy transfer pattern
Lin, Qing; Wu, Yi; Li, Gang; He, Bing [Center for Quantum Optics and Quantum Information, Universidad Mayor, Chile]
The energy transfer between different subsystems or different vibration modes is always one of the most interested problems in the study of the resonance phenomena in coupled nonlinear dynamical systems. With an optomechanical system operating in the regime of unresolved sideband, where its mechanical frequency is lower than the cavity field damping rate, we illustrate the existence of a special nonlinear resonance phenomenon. This type of previously unknown resonance manifests an organized pattern of the coupled cavity field and mechanical oscillation, so that the cavity field precisely pushes the mechanical oscillator within an appropriate small time window in each mechanical oscillation period and the mechanical energy will increase by a jump of almost fixed amount after each oscillation cycle. The scenario is realized at a resonance point where the frequency difference of two driving fields matches the mechanical frequency of the system, and this condition of drive-frequency match is found to trigger a mechanism to lock the two subsystems of an unresolved-sideband optomechanical system into a highly ordered energy transfer as the above mentioned. Due to a significantly enhanced nonlinearity in the vicinity of the resonance point, optical frequency combs can be generated under pump powers of thousand times lower, as compared to the use of a single-tone driving field for the purpose. An unresolved sideband system under the drives without satisfying the resonance condition also demonstrates other interesting dynamical behaviors. Most of all, by providing a realistic picture for the nonlinear optomechanical dynamics in unresolved sideband regime, our study points to a direction to observe novel dynamical phenomena and realize other applications with the systems of less technical restrictions.
2023-08-01T00:00:00ZBayesian sampling with BeAtlas, a grid of synthetic Be star spectra I. Recovering the fundamental parameters of α Eri and β CMi
https://repositorio.umayor.cl/xmlui/handle/sibum/9448
Bayesian sampling with BeAtlas, a grid of synthetic Be star spectra I. Recovering the fundamental parameters of α Eri and β CMi
Rubio, A. C.; Carciofi, A. C.; Ticiani, P.; Mota, B. C.; Vieira, R. G.; Faes, D. M.; Genaro, M.; Amorim, T. H. de; Klement, R.; Araya, I. [Centro de Óptica e Información Cuántica, Vicerrectoría de Investigación, Universidad Mayor, Chile]; Arcos, C.; Cure, M.; Souza, A. Domiciano de; Georgy, C.; Jones, C. E.; Suffak, M. W.; Silva, A. C. F.
Classical B emission (Be) stars are fast rotating, near-main-sequence B-type stars. The rotation and the presence of circumstellar discs profoundly modify the observables of active Be stars. Our goal is to infer stellar and disc parameters, as well as distance and interstellar extinction, using the currently most favoured physical models for these objects. We present BEATLAS, a grid of
non-local thermodynamic equilibrium radiative transfer models for Be stars, calculated with the HDUST code. The grid was coupled with a Monte Carlo Markov chain (MCMC) code to sample the posterior distribution. We test our method on two well-studied Be stars, α Eri and β CMi, using photometric, polarimetric, and spectroscopic data as input to the code. We recover literature determinations for most of the parameters of the targets, in particular the mass and age of α Eri, the disc parameters of β CMi, and their distances and inclinations. The main discrepancy is that we estimate lower rotational rates than previous works. We confirm previously detected signs of disc truncation in β CMi and note that its inner disc seems to have a flatter density slope than its outer disc. The correlations between the parameters are complex, further indicating that exploring the entire parameter space simultaneously is a more robust approach, statistically. The combination of BEATLAS and Bayesian-MCMC techniques proves successful, and a powerful new tool for the field: The fundamental parameters of any Be star can now be estimated in a matter of hours or days.
2023-09-01T00:00:00ZMutual Information and Quantum Discord in Quantum State Discrimination with a Fixed Rate of Inconclusive Outcomes
https://repositorio.umayor.cl/xmlui/handle/sibum/9112
Mutual Information and Quantum Discord in Quantum State Discrimination with a Fixed Rate of Inconclusive Outcomes
Solis-Prosser, Miguel Ángel; Neves, Leonardo; Delgado, Aldo; Jimenez, Omar [Univ Mayor, Fac Ciencias, Ctr Opt & Informac Cuant, Chile]
We studied the mutual information and quantum discord that Alice and Bob share when Bob implements a discrimination with a fixed rate of inconclusive outcomes (FRIO) onto two pure non-orthogonal quantum states, generated with arbitrary a priori probabilities. FRIO discrimination interpolates between minimum error (ME) and unambiguous state discrimination (UD). ME and UD are well known discrimination protocols with several applications in quantum information theory. FRIO discrimination provides a more general framework where the discrimination process together with its applications can be studied. In this setting, we compared the performance of optimum probability of discrimination, mutual information, and quantum discord. We found that the accessible information is obtained when Bob implements the ME strategy. The most (least) efficient discrimination scheme is ME (UD), from the point of view of correlations that are lost in the initial state and remain in the final state, after Bob's measurement.
2021-01-01T00:00:00Z