Resonance and Relaxation

Ryogo Kubo, Morikazu Toda, Natsuki Hashitsume

V. S. Babichenko

The relaxation processes in an ultra-cold degenerate atomic Fermi gas near a Feshbach resonance are considered. It is shown that the relaxation rate of the molecules being in a resonance with the atomic Fermi system is of the order of the part of the chemical potential determined by the interaction between resonance molecules. In this connection the lower part of the excitation spectrum in the system of resonance molecules is not well-defined.

Ryogo Kubo, Morikazu Toda, Natsuki Hashitsume

Yasuaki Masumoto, Takashi Suzuki, K. Kawana +1 more

Exciton spin stability in InP quantum dots at the elevated temperatures is studied by measuring resonant spin orientation of excitons. With the increase of temperature, spin relaxation time becomes shorter and resonant spin orientation of excitons is reduced. It is 12 times longer than the lifetime of 260 ps at 5 K but is comparable with the lifetime around 50 K. The amplitude of the resonant spin orientation structure changes with the change of the excitation photon energy, reflecting the competition between the spin relaxation through the energy relaxation and the energy relaxation. Spin relaxation time through the energy relaxation is comparable with phonon-mediated relaxation time and is much shorter than the spin relaxation time within the bright and dark exciton states.

Marc Cheneau

Bernard Zygelman, A. Dalgarno

We demonstrate that shape resonances can enhance the dipolar relaxation rate of atomic gases in the zero-temperature limit. We show that the rate coefficients exhibit resonance features as a bias magnetic field is swept through a region characterized by the resonances. Unlike Feshbach resonances which also enhance dipolar relaxation rates, the shape resonance mechanism does not affect the value of the collision s-wave scattering length. We discuss possible applications of the proposed mechanism in cold atomic gases or bosonic condensates.