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تسجيل مستخدم جديدIn situ Ramsey Interferometry and Diffraction Echo with an Ultracold Fermi Gas
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We report on the first observation of Bragg scattering of an ultracold $^6$Li Fermi gas. We demonstrate a Ramsey-type matter-wave interferometer based on Bragg diffraction and find robust signatures of persistent matter wave coherences using an echo pulse sequence. Because of the Pauli principle, the diffracted fermions oscillate nearly unperturbed in the trapping potential for long times beyond 2 s. This suggests extremely long coherence times. On these timescales, only the presence of a $^{87}$Rb cloud seems sufficient to induce noticeable perturbations.
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We report on the observation of Bragg scattering of an ultracold Fermi gas of 6Li atoms at a dynamic optical potential. The momentum states produced in this way oscillate in the trap for time scales on the order of seconds, nearly unperturbed by coll
isions, which are absent for ultracold fermions due to the Pauli principle. In contrast, interactions in a mixture with 87Rb atoms lead to rapid damping. The coherence of these states is demonstrated by Ramsey-type matter wave interferometry. The signal is improved using an echo pulse sequence, allowing us to observe coherence times longer than 100 mus. Finally we use Bragg spectroscopy to measure the in-situ momentum distribution of the 6Li cloud. Signatures for the degeneracy of the Fermi gas can be observed directly from the momentum distribution of the atoms inside the trap.
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