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Weak Antilocalization in Quantum Wells

100%

Knap W., Skierbiszewski C., Litwin-Staszewska E., Kobbi F., Zduniak A., Robert J., Pikus G., Iordanskii S., Mosser V., Zekentes K.

Acta Physica Polonica A

1995

vol. 87

issue 2

427-432

Spin relaxation in degenerated two-dimensional (2D) electron gas is studied by measurements of the magnetic field dependence of the weak antilocalization corrections to the conductivity in GaInAs quantum wells. Consistent quantitative (up to order of magnitude) description of weak antilocalization data on GaAs like heterojunctions and quantum wells was obtained. Our results show that spin precession around the effective magnetic field direction as described by the Dyakonov-Perel model is the main spin relaxation mechanism in degenerated 2D electron gas in semiconductors with no inversion symmetry.

Positronium for Antihydrogen Production in the AEGIS Experiment

43%

Consolati G., Aghion S., Amsler C., Bonomi G., Brusa R., Caccia M., Caravita R., Castelli F., Cerchiari G., Comparat D., Demetrio A., Di Noto L., Doser M., Evans C., Fanì M., Ferragut R., Fesel J., Fontana A., Gerber S., Giammarchi M., Gligorova A., Guatieri F., Haider S., Hinterberger A., Holmestad H., Kellerbauer A., Khalidova O., Krasnicky D., Lagomarsino V., Lansonneur P., Lebrun P., Malbrunot C., Mariazzi S., Marton J., Matveev V., Mazzotta Z., Müller S., Nebbia G., Nedelec P., Oberthaler M., Pacifico N., Pagano D., Penasa L., Petracek V., Prelz F., Prevedelli M., Ravelli L., Rienaecker B., Robert J., Røhne O., Rotondi A., Sandaker H., Santoro R., Smestad L., Sorrentino F., Testera G., Tietje I., Widmann E., Yzombard P., Zimmer C., Zmeskal J., Zurlo N.

Acta Physica Polonica A

2017

vol. 132

issue 5

1443-1449

The primary goal of the Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEGIS) collaboration is to measure for the first time precisely the gravitational acceleration of antihydrogen, H̅, a fundamental issue of contemporary physics, using a beam of antiatoms. Indeed, although indirect arguments have been raised against a different acceleration of antimatter with respect to matter, nevertheless some attempts to formulate quantum theories of gravity, or to unify gravity with the other forces, consider the possibility of a non-identical gravitational interaction between matter and antimatter. We plan to generate H̅ through a charge-exchange reaction between excited Ps and antiprotons coming from the Antiproton Decelerator facility at CERN. It offers the advantage to produce sufficiently cold antihydrogen to make feasible a measurement of gravitational acceleration with reasonable uncertainty (of the order of a few percent). Since the cross-section of the above reaction increases with n⁴, n being the principal quantum number of Ps, it is essential to generate Ps in a highly excited (Rydberg) state. This will occur by means of two laser excitations of Ps emitted from a nanoporous silica target: a first UV laser (at 205 nm) will bring Ps from the ground to the n=3 state; a second laser pulse (tunable in the range 1650-1700 nm) will further excite Ps to the Rydberg state.

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Weak Antilocalization in Quantum Wells

Positronium for Antihydrogen Production in the AEGIS Experiment