Gravitational Radiation, Vorticity And Super–Energy: A Conspicuous Threesome

We elaborate on the link relating gravitational radiation, vorticity and a flux of super–energy on the plane orthogonal to the vorticity vector. We examine the vorticity appearing in the congruence of observers at the outside of the source, as well as the vorticity of the fluid distribution, the source of the gravitational radiation is made of. The information provided by the study of the physical aspects of the source poses new questions which could, in principle, be solved by the observational evidence. Besides the study of the theoretical issues associated to such relationship, we also stress the new observational possibilities to detect gravitational radiation, appearing as consequence of the above mentioned link. The high degree of development achieved in the gyroscope technology, as well as recent proposals to detect rotations by means of ring lasers, atom interferometers, atom lasers and anomalous spin–precession experiments, lead us to believe that an alternative to the laser interferometers used so far to detect gravitational waves, may be implemented based on the detection of the vorticity associated with gravitational radiation. Additionally, this kind of detectors might be able to elucidate the open question about the physical properties of the tail of the waves appearing as the consequence of the violation of the Huygens’s principle in general relativity.

An ultra-high flux matter-wave laser from a highly flexible ioffe-pritchard trap

This thesis describes the development and construction of a machine for producinghigh atom-number Bose-Einstein Condensates (BECs). Emphasis is given to thenovel Ioe-Pritchard magnetic trap used, that consists exclusively of circular coils.This allowed us to achieve higher gradients and thus tighter connements [1].This thesis also describes a novel atom-laser output-coupler based on time dependentadiabatic potentials (TDAP) [2]. In this method strong rf elds are usedto deform the trapping potential. Contrary to the traditional weak rf methods thatextracts the atoms from the center of the BEC, the TDAP atom lasers emerge fromthe edge of the condensate. This provides the atom lasers with low divergence.Furthermore, the atoms are outcoupled from the BEC at an arbitrarily large rateleading to uxes per trapped atom sixteen times higher compared to the brightestquasi-continuous atom laser.Finally, presented is the coldest thermal atom beam to date. Using the TDAPoutcoupling, we produced thermal atom beams with temperatures as low as 200 nK,which makes it, by two orders of magnitude, the coldest thermal beam ever observed.Something like that would be very useful for high-resolution spectroscopy of ultracoldcollisions.