EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:
Oscilações Quânticas de Neutrinos e o Prêmio Nobel de Física de 2016
Prof. Dr. Marcelo M. Guzzo
Instituto de Física da UNICAMP
Resumen:
O Prêmio Nobel de Física de 2015 foi concedido aos Profs. McDonald e Kajita, coordenadores dos experimentos SNO e Superkamiokande, pelas “descobertas das oscilações quânticas de neutrinos, que mostraram que os neutrinos têm massa”. Neste seminário apresentaremos as características e a história desta partícula misteriosa e onipresente cujos estudos receberam, até o momento, oito Prêmios Nobel de Física. Enfatizaremos as oscilações quânticas de neutrinos e a necessidade de massa para os neutrinos.
Fecha: 24 de junio de 2016- (viernes) – Lugar: Sala 212 – Auditorio del Departamento de Física – Horário: 10h15min
EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:
On The Spin Evolution of Isolated Pulsars
Dr. Oliver Q. Hamil
Pós-doutorando – UFSC/FSC
Resumen:
Isolated pulsars are a class of neutron stars that are spinning at high frequencies, and emit beams of electromagnetic radiation into space which appear like lighthouses to observers on earth. Observations of these objects span a few decades, and some of them have been documented with very high accuracy. Measurements of the pulsar rotational velocity Ω, and its time derivatives Ω and ̇ Ω, show that they slow down over time. The generally ̈ accepted explanation for the spin-down is that the pulsars behave like magnetic dipoles that lose energy in the form of electromagnetic radiation causing them to slow over time. This assumption of magnetic dipole radiation (MDR) leads to a general power law constructed from observation, Ω = ̇ −KΩ n is exactly 3 for MDR, but accurate observational measurements consistently yield values of 1.0 < n < 2.8. The reason for this discrepancy is unknown. In the present work we aim to improve understanding of the braking index through a two pronged investigation. We approach the problem by allowing for dynamical changes in the neutron star properties required in the braking index solution. We develop a frequency dependent model of the braking index that allows changing moment of inertia of the star, and changes in magnetic field properties in the MDR torque mechanism. For the first time, we have the opportunity to use physically realistic equations of state, along with state of the art computational codes to determine the dynamic properties of the neutron star needed in the modified braking index model. We probe the stars at constant baryonic rest masses ranging from 1.0M to 2.2M over a range of frequency spanning from zero to the Kepler (mass shedding) frequency for each star. We find that the braking index is sucseptible to changes in moment of inertia at very high frequencies, but unaffected in the lower frequency range where all of the reliably measured pulsars rotate. At low frequencies, however, we were able to again match the measured values by allowing for a change in the orientation of the magnetic moment of the dipole over time, in light of recent developments in the literature.
Fecha: 10 de junio de 2016- (jueves) – Lugar: Sala 212 – Auditorio del Departamento de Física – Horário: 10h15min
EL PROGRAMA DE POSGRADO EN FÍSICA invita a todos para lo seminario:
Generalized Geometric Time-Energy Uncertainty Relations
Prof. Dr. Lucas C. Céleri
Universidade Federal de Goiás – UFG
Resumen:
The attempt to gain a theoretical understanding of the concept of time in quantum mechanics has triggered significant progress towards the search for faster and more efficient quantum technologies. One of such advances consists in the interpretation of the time-energy uncertainty relations as lower bounds for the minimal evolution time between two distinguishable states of a quantum system, also known as quantum speed limits. We will discuss how the non uniqueness of a measure of distinguishability defined on the quantum state space affects the quantum speed limits and can be exploited in order to derive improved bounds. Specifically, we establish an infinite family of quantum speed limits valid for arbitrary evolutions, based on an information geometric formalism, thus deriving novel bounds which are tighter than any established one based on the conventional quantum Fisher information. These results can find applications in the optimization and control of quantum technologies such as quantum computation and metrology, and might provide new insights in fundamental investigations of quantum thermodynamics.
Fecha: 20 de mayo de 2016- (viernes) – Lugar: Sala 114 – Sala del reuniones del Departamento de Física – Horário: 10h15min
