Using photoemission spectroscopy to probe a strongly interacting Fermi gas

  title={Using photoemission spectroscopy to probe a strongly interacting Fermi gas},
  author={John T. Stewart and J. P. Gaebler and Deborah S. Jin},
Ultracold atomic gases provide model systems in which to study many-body quantum physics. Recent experiments using Fermi gases have demonstrated a phase transition to a superfluid state with strong interparticle interactions. This system provides a realization of the ‘BCS–BEC crossover’ connecting the physics of Bardeen–Cooper–Schrieffer (BCS) superconductivity with that of Bose–Einstein condensates (BECs). Although many aspects of this system have been investigated, it has not yet been… 
Angle-resolved photoemission spectroscopy of a Fermi–Hubbard system
Angle-resolved photoemission spectroscopy (ARPES) measures the single-particle excitations of a many-body quantum system with energy and momentum resolution, providing detailed information about
Radio-frequency spectroscopic measurement for pairing gap in an ultracold Fermi gas
The study of ultracold Fermi gases has exploded a variety of experimental and theoretical research since the achievement of degenerate quantum gases in the lab, which expands the research range over
Thermodynamic Measurements in a Strongly Interacting Fermi Gas
Strongly interacting Fermi gases provide a clean and controllable laboratory system for modeling strong interparticle interactions between fermions in nature, from high temperature superconductors to
Metastability and coherence of repulsive polarons in a strongly interacting Fermi mixture
Radio-frequency spectroscopy is used to measure the complete excitation spectrum of fermionic 40K impurities resonantly interacting with a Fermi sea of 6Li atoms, and shows that a well-defined quasiparticle exists for strongly repulsive interactions, and finds that when the effective range is of the order of the interparticle spacing, there is a substantial increase in the lifetime of the quAsiparticles.
Strong Correlations in Ultracold Fermi Gases
Ultracold atomic gases provide an ideal system with which to study fundamental many-body physics. Exhibiting universal interactions in clean and controllable environments, long-used simple models as
Theory of photoemission-type experiment in the BCS-BEC crossover regime of a superfluid Fermi gas
We theoretically investigate the recent photoemission-type experiment on 40K Fermi gases done by JILA group. Including pairing fluctuations within a strong-coupling T-matrix theory, as well as
Strongly interacting Fermi gases
Strongly interacting gases of ultracold fermions have become an amazingly rich test-bed for many-body theories of fermionic matter. Here we present our recent experiments on these systems. Firstly,
Thermodynamics of Fermi Gases
Recently, ultra-cold atoms have established a very fruitful connection with condensed matter physics, nuclear physics, astrophysics, and high energy physics on many-body problems in strongly
BCS-BEC Crossover and the Unitary Fermi Gas
The crossover from weak coupling Bardeen-Cooper-Schrieffer (BCS) pairing to a Bose-Einstein condensate (BEC) of tightly bound pairs, as a function of the attractive interaction in Fermi systems, has
Enhanced paraconductivity-like fluctuations in the radiofrequency spectra of ultracold Fermi atoms
Radiofrequency spectroscopy provides a microscopic probe of fermionic pairing in ultracold Fermi gases. Calculations now suggest that there is a one-to-one correspondence between the theory of these


Determination of the fermion pair size in a resonantly interacting superfluid
This work realizes a superfluid spin mixture in which such interactions have negligible influence and presents fermion pair dissociation spectra that reveal the underlying pairing correlations, and determines that the spectroscopic pair size in the resonantly interacting gas is 20 per cent smaller than the interparticle spacing.
Vortices and superfluidity in a strongly interacting Fermi gas
Observation of vortex lattices in a strongly interacting, rotating Fermi gas that provide definitive evidence for superfluidity are reported and the crossover from a Bose–Einstein condensate of molecules to a Bardeen–Cooper–Schrieffer superfluid of loosely bound pairs is explored.
Theory of ultracold atomic Fermi gases
The physics of quantum degenerate atomic Fermi gases in uniform as well as in harmonically trapped configurations is reviewed from a theoretical perspective. Emphasis is given to the effect of
Creation of ultracold molecules from a Fermi gas of atoms
The creation and quantitative characterization of ultracold 40K2 molecules is reported, which can be converted back to atoms by reversing the scan, and the small binding energy of the molecules is controlled by detuning the magnetic field away from the Feshbach resonance, and can be varied over a wide range.
Potential energy of a 40K Fermi gas in the BCS-BEC crossover.
A measurement of the potential energy of an ultracold trapped gas of 40K atoms in the BCS-BEC crossover is presented and the temperature dependence of this energy at a wide Feshbach resonance is investigated, where the gas is in the unitarity limit.
Radio frequency spectroscopy of a strongly imbalanced Feshbach-resonant Fermi gas
A su!ciently large species imbalance (polarization) in a tw o-component Feshbach resonant Fermi gas is known to drive the system into its normal state. We show that the resulting stronglyinteracting
Observation of resonance condensation of fermionic atom pairs.
In order to search for condensation on either side of the resonance, a technique that pairwise projects fermionic atoms onto molecules is introduced; this enables to measure the momentum distribution of fermionics atom pairs.
Bragg spectroscopy of cold atomic Fermi gases
We propose a Bragg spectroscopy experiment to measure the onset of superfluid pairing in ultracold trapped Fermi gases. In particular, we study two-component Fermi gases in the weak coupling BCS and
Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
The appearance of an energy gap with moderate evaporative cooling suggests that the full evaporation of an ultracold two-component gas of 6Li atoms brought the strongly interacting system deep into a superfluid state.