Stabilization of an arbitrary profile for an ensemble of half-spin systems

We consider the feedback stabilization of a variable profile for an ensemble of non interacting half spins described by the Bloch equations. We propose an explicit feedback law that stabilizes asymptotically the system around a given arbitrary target profile. The convergence proof is done when the target profile is entirely in the south hemisphere or in the north hemisphere of the Bloch sphere. The convergence holds for initial conditions in a H^1 neighborhood of this target profile. This convergence is shown for the weak H^1 topology. The proof relies on an adaptation of the LaSalle invariance principle to infinite dimensional systems. Numerical simulations illustrate the efficiency of these feedback laws, even for initial conditions far from the target profile.Comment: 6 pages, 2 figure

Stockmarket comovements revisited

We revisit the issue of comovements of emerging and developed stockmarkets, and provide a simultaneous treatment of data for the eighties and nineties. We show that while emerging markets experience greater instability in the long term than their developed counterparts, there is room for short-term strategies to take advantage of profit opportunities in the emerging markets, especially in India.

Stabilization of photon-number states via single-photon corrections: a first convergence analysis under an ideal set-up

This paper presents a first mathematical convergence analysis of a Fock states feedback stabilization scheme via single-photon corrections. This measurement-based feedback has been developed and experimentally tested in 2012 by the cavity quantum electrodynamics group of Serge Haroche and Jean-Michel Raimond. Here, we consider the infinite-dimensional Markov model corresponding to the ideal set-up where detection errors and feedback delays have been disregarded. In this ideal context, we show that any goal Fock state can be stabilized by a Lyapunov-based feedback for any initial quantum state belonging to the dense subset of finite rank density operators with support in a finite photon-number sub-space. Closed-loop simulations illustrate the performance of the feedback law.Comment: 2 figures, extended version of the IEEE CDC2015 conference pape

Gate generation for open quantum systems via a monotonic algorithm with time optimization

We present a monotonic numerical algorithm including time optimization for generating quantum gates for open systems. Such systems are assumed to be governed by Lindblad master equations for the density operators on a large Hilbert-space whereas the quantum gates are relative to a sub-space of small dimension. Starting from an initial seed of the control input, this algorithm consists in the repetition of the following two steps producing a new control input: (A) backwards integration of adjoint Lindblad-Master equations (in the Heisenberg-picture) from a set of final conditions encoding the quantum gate to generate; (B) forward integration of Lindblad-Master equations in closed-loop where a Lyapunov based control produced the new control input. The numerical stability is ensured by the stability of both the open-loop adjoint backward system and the forward closed-loop system. A clock-control input can be added to the usual control input. The obtained monotonic algorithm allows then to optimise not only the shape of the control imput, but also the gate time. Preliminary numerical implementations indicate that this algorithm is well suited for cat-qubit gates, where Hilbert-space dimensions (2 for the Z-gate and 4 for the CNOT-gate) are much smaller than the dimension of the physical Hilbert-space involving mainly Fock-states (typically 20 or larger for a single cat-qubit). This monotonic algorithm, based on Lyapunov control techniques, is shown to have a straightforward interpretation in terms of optimal control: its stationary conditions coincides with the first-order optimality conditions for a cost depending linearly on the final values of the quantum states.Comment: Submitted, 4 figure

The undergratuate degree in nursing and the meanings derived from the mentoring

Objective: Analyzing the meanings produced in free drawings and built by students in tutoring scenario while learning in undergraduate. Method: A qualitative research. The scenario was a private college in Rio de Janeiro. The subjects were 87 students from 1st to 7th periods in nursing. The ethical and legal procedures were present and the authorization of the Ethics in Research-Protocol. n.º 581-11. Results: The analysis of data collected contemplated the thematic analysis. From reading the drawings we obtained an understanding that students value the mentoring, to having to build learning based on responsibility. Conclusion: The study aims to encourage students and teachers in achieving the best quality training

Elements of the teacher’s face in the tutorial setting: implications in nurses’ training

Objetivos: Conhecer os elementos presentes na face do professor que determinam o processo de ensino-aprendizagem no cenário tutorial e analisar suas implicações na formação de enfermeiros. Método: Trata-se de um estudo qualitativo realizado em um centro universitário particular localizado na região serrana do estado do Rio de Janeiro. Os participantes deste estudo foram onze estudantes regularmente matriculados no sétimo período da graduação no ano de 2014. O estudo foi aprovado pelo Comitê de Ética em Pesquisa com protocolo n.º 568.300. Resultados: Os dados convergiram para a construção de três categorias que dispõem de forma particular sobre os seguintes elementos da face do professor que implicam de forma agradável e desagradável aos olhos dos estudantes: expressões faciais, sobrancelhas, olhos e boca. Conclusão: Esperamos que as reflexões sobre os elementos conhecidos no corpo do professor disparem novos estudos em outros espaços de investigação institucional sobre criação do papel de ser enfermeiro