Parameter estimation with mixed quantum states

We consider quantum enhanced measurements with initially mixed states. We show very generally that for any linear propagation of the initial state that depends smoothly on the parameter to be estimated, the sensitivity is bound by the maximal sensitivity that can be achieved for any of the pure states from which the initial density matrix is mixed. This provides a very general proof that purely classical correlations cannot improve the sensitivity of parameter estimation schemes in quantum enhanced measurement schemes.Comment: 6 page

Flipped classroom applied to Neurosurgery in undergraduate medical education

To compare the academic achievement obtained in Neurosurgery in a class of undergraduate students according to the pedagogical methodology employed: flipped classroom (FC) versus traditional lecture. Students’ satisfaction with the FC model is also analyzed. A quasi-experimental study was designed. The traditional lecture was the pedagogical method employed in teaching units (TUs) 1, 2, and 3 (61, 60, and 66 enrolled students, respectively), whereas TU 4 (69 enrolled students) used the FC methodology. The dropout rate was lower, whereas the academic achievement and the rate of correct answers were higher in TU 4 compared to the rest of the TUs, but these results were not statistically significant. However, the mean score obtained in Neurosurgery was significantly higher in TU 4 compared to the rest of the TUs (p = 0.042). Active learning activities based on clinical cases were positively emphasized. The main weakness was with the time consumed for video-recorded lecture viewing. The FC approach showed better academic results than traditional lectures when comparing students in the same Medical School during the same academic year undergoing the same exam. The students rated the FC approach positively, considering it stimulating and useful for learnin

Obesidad, nutrición y actividad física

La cantidad y calidad de actividad física se ha reducido considerablemente en la sociedad actual. El desequilibrio que se produce cuando el consumo de alimentos supera el gasto energético conlleva un aumento de peso corporal y consecuentemente de la obesidad. Varios son los factores determinantes de la obesidad, así como sus consecuencias. Para tratar una persona obesa es necesario conocer, en primer lugar, el agente desencadenante de la enfermedad. Los profesores de Educación Física, junto con las aportaciones de los profesionales de otras áreas de las ciencias del deporte, pueden ser de vital importancia para ayudar a los niños, niñas y adolescentes con problemas causados por el exceso de peso corporal

Pemphigus Vulgaris - A Pediatric Case

O Pênfigo Vulgar é uma doença auto-imune rara na infância,com evolução crónica e mortalidade significativa. A doença manifesta-se por lesões vesiculares, semelhantes a infecções benignas, mas que são refractárias ao tratamento sintomático e persistem após a fase aguda. Apresenta-se o caso de uma criança de três anos com lesões muco-cutâneas orais, persistentes. A biópsia permitiu o diagnóstico de Pênfigo Vulgar, tendo sido iniciada terapia corticosteróide sistémica. A dificuldade no controlo da doença levou à introdução de outros fármacos imunossupressores, até se atingir a estabilidade clínica. Todas as opções de tratamento do Pênfigo apresentam efeitos iatrogénicos, sendo imprescindível um equilíbrio entre controlo da doença e qualidade de vida do doente

Enhancing image contrast using coherent states and photon number resolving detectors

We experimentally map the transverse profile of diffraction-limited beams using photon-number-resolving detectors. We observe strong compression of diffracted beam profiles for high detected photon number. This effect leads to higher contrast than a conventional irradiance profile between two Airy disk-beams separated by the Rayleigh criterion.Comment: 7 pages, 3 figures, accepted for publication in Optics Expres

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Coherent Superposition States as Quantum Rulers

We explore the sensitivity of an interferometer based on a quantum circuit for coherent states. We show that its sensitivity is at the Heisenberg limit. Moreover we show that this arrangement can measure very small length intervals

Two-photon diffraction and quantum lithography

We report a proof-of-principle experimental demonstration of quantum lithography. Utilizing the entangled nature of a two-photon state, the experimental results have bettered the classical diffraction limit by a factor of two. This is a quantum mechanical two-photon phenomenon but not a violation of the uncertainty principle.Comment: 5 pages, 5 figures Submitted to Physical Review Letter

Generation of Entangled N-Photon States in a Two-Mode Jaynes-Cummings Model

We describe a mathematical solution for the generation of entangled N-photon states in two field modes. A simple and compact solution is presented for a two-mode Jaynes-Cummings model by combining the two field modes in a way that only one of the two resulting quasi-modes enters in the interaction term. The formalism developed is then applied to calculate various generation probabilities analytically. We show that entanglement, starting from an initial field and an atom in one defined state may be obtained in a single step. We also show that entanglement may be built up in the case of an empty cavity and excited atoms whose final states are detected, as well as in the case when the final states of the initially excited atoms are not detected.Comment: v2: 5 pages, RevTeX4, minor text changes + 1 figure added, revised version to be published in PRA, May 200