Bragg spectroscopy and Ramsey interferometry with an ultracold Fermi gas

Abstract

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 collisions, 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.

19 pages, 10 figures

References in corpus (15)

• Atom interferometry with trapped Fermi gases
• Bragg spectroscopy of a strongly interacting Fermi gas
• Quantum-degenerate mixture of fermionic lithium and bosonic rubidium gases
• Feshbach resonances in mixtures of ultracold ${}^6$Li and ${}^{87}$Rb gases
• Resonant scattering properties close to a p-wave Feshbach resonance
• Critical Temperature and Condensate Fraction of a Fermion Pair Condensate
• Spectroscopy of Superfluid Pairing in Atomic Fermi Gases
• Confinement effects in a guided-wave interferometer with millimeter-scale arm separation
• Feshbach resonances in ultracold 85Rb-87Rb and 6Li-87Rb mixtures
• Bragg Spectroscopy of Vortex Lattices in Bose-Einstein condensates
• Bragg Spectroscopy of Cold Atomic Fermi Gases
• Coherent Molecular Optics using Sodium Dimers
• Bragg scattering of Cooper pairs in an ultra-cold Fermi gas
• Ultracold Thermalization of ${}^7$Li and ${}^{87}$Rb
• In situ Ramsey Interferometry and Diffraction Echo with an Ultracold Fermi Gas

Cited by in corpus (5)

• Contact and sum-rules in a near-uniform Fermi gas at unitarity
• Rabi Interferometry and Sensitive Measurement of the Casimir-Polder Force with Ultra-Cold Gases
• Velocimetry of cold atoms by matterwave interferometry
• Spectroscopic Bogoliubov features near the unitary limit
• Calibrating the momentum width of a trapped Bose-Einstein condensate by one-dimensional optical lattice pulse sequences