Direct observation of the Fermi surface in an ultracold atomic gas

Abstract

The ideal (i.e. noninteracting), homogeneous Fermi gas, with its characteristic sharp Fermi surface in the momentum distribution, is a fundamental concept relevant to the behavior of many systems. With trapped Fermi gases of ultracold atoms, one can realize and probe a nearly ideal Fermi gas, however these systems have a nonuniform density due to the confining potential. We show that the effect of the density variation, which typically washes out any semblance of a Fermi surface step in the momentum distribution, can be mitigated by selectively probing atoms near the center of a trapped gas. With this approach, we have directly measured a Fermi surface in momentum space for a nearly ideal gas, where the average density and temperature of the probed portion of the gas can be determined from the location and sharpness of the Fermi surface.

References in corpus (11)

• Observation of resonance condensation of fermionic atom pairs
• Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance
• Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
• Large momentum part of fermions with large scattering length
• Energetics of a strongly correlated Fermi gas
• Exploring the Thermodynamics of a Universal Fermi Gas
• Using photoemission spectroscopy to probe a strongly interacting Fermi gas
• Generalized Virial Theorem and Pressure Relation for a strongly correlated Fermi gas
• Bose Einstein Condensate in a Box
• Verification of universal relations in a strongly interacting Fermi gas
• Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy

Cited by in corpus (16)

• Bose-Einstein condensation of atoms in a uniform potential
• Homogeneous Atomic Fermi Gases
• Quantum Gases in Optical Boxes
• Measurement of the Homogeneous Contact of a Unitary Fermi gas
• Breakdown of Fermi liquid description for strongly interacting fermions
• Quantum mechanical limitations to spin diffusion in the unitary Fermi gas
• Pseudogaps in strongly interacting Fermi gases
• Mapping of the unoccupied states and relevant bosonic modes via the time dependent momentum distribution
• Local observation of pair-condensation in a Fermi gas at unitarity
• Absence of heating in a uniform Fermi gas created by periodic driving
• Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas
• Quantum Decoherence of Phonons in Bose-Einstein Condensates
• Detecting $\pi$-phase superfluids with $p$-wave symmetry in a quasi-1D optical lattice
• Multipolar Fermi-surface deformation in a Rydberg-dressed Fermi gas with long-range anisotropic interactions
• Non-Galilean response of Rashba coupled Fermi gases
• Second-order response theory of radio-frequency spectroscopy for cold atoms