Creating and sharing knowledge for telecommunications

Completeness and interpolation of almost-everywhere quantification over finitely additive measures

on 24-05-2013

... Joao Rasga, SQIG-Instituto de Telecomunições / IST-Universidade de Lisboa

May 24, 2013, Friday, 16h15m.

Abstract: We give an axiomatization of first-order logic enriched with the almost-everywhere quantifier over finitely additive measures. Using an adapted version of the consistency property adequate for dealing with this generalized quantifier, we show that such a logic is both strongly complete and enjoys Craig interpolation, relying on a (countable) model existence theorem. We also discuss possible extensions of these results to the almost-everywhere quantifier over countably additive measures. The talk reports on joint work with Wafik Lotfallah and Cristina Sernadas.

Room: 3.10, Mathematics

Support: SQIG/Instituto de Telecomunicações with support from FCT and FEDER namely by the FCT project PEst-OE/EEI/LA0008/2013. More Information..

Seminar - Population transfer between quantum states to perfection: Stimulated Raman Adiabatic Passage (STIRAP)

on 23-05-2013

... 23/05/2013, 15:00 ­ Sala P3.10, Mathematics Building, IST.

In many areas of science (e.g. physics, chemistry, quantum information) controlled modification and in particular efficient transfer of population between quantum states is wanted. Many schemes are known that allow varying the usually thermal population distribution. Of particular interest are means for selective and efficient transfer of population from quantum state i to quantum state f. “Efficient” means that nearly 100% of the population residing initially in state i reaches state f. This also implies high selectivity as no other quantum state receives population. Traditional techniques such as Raman scattering, optical pumping or stimulated emission pumping fail to reach the goal. Spontaneous emission, which channels population into other levels,is a main problem. STIRAP solves that problem through a surprisingly simple, but at first glance very puzzling, sequence of radiative interactions: The quantum system is first exposed to the radiation field which connects the final state with an intermediate state (thus, it does not couple to the quantum state which carries initially the population) before the second radiation field couples the initial state to the same intermediate one. The basic phenomena and the physics building blocks of this process, the concept of which is now applied in very many areas, are presented and explained.

Quantum Computation and Information Seminar

Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via projects PTDC/EEA-TEL/103402/2008 QuantPrivTel, PEst-OE/EEI/LA0008/2013 and Landauer (GA 318287). More Information..