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We show the emergence of a strongly interacting Bose-Fermi mixture from a two-component Fermi mixture with population imbalance. By analyzing in situ density profiles of $^6$Li atoms in the BCS-BEC crossover regime we identify a critical…

Statistical Mechanics · Physics 2009-11-13 Yong-il Shin , André Schirotzek , Christian H. Schunck , Wolfgang Ketterle

The spatial structure of a two-dimensional homogeneous mixture of fermionic atoms in two hyperfine states is analyzed throughout the BEC-BCS crossover. Within the BCS-Leggett mean-field model we consider three functions: the pair wave…

Quantum Gases · Physics 2022-04-20 J. C. Obeso-Jureidini , V. Romero-Rochin

We consider the response of the density of a fermion ensemble to an applied weak static magnetic field. It is known that for non-interacting Fermi gas, this response is fully characterized by the Fermi volume and the Berry curvature on the…

Strongly Correlated Electrons · Physics 2017-09-06 Jing-Yuan Chen

We use all-optical methods to produce a highly-degenerate Fermi gas of spin-1/2 $^6$Li atoms. A magnetic field tunes the gas near a collisional (Feshbach) resonance, producing strong interactions between spin-up and spin-down atoms. This…

Other Condensed Matter · Physics 2009-11-13 A. Turlapov , J. Kinast , B. Clancy , Le Luo , J. Joseph , J. E. Thomas

The two-species cold atomic Fermi gas with attractive short-range interactions in two spatial dimensions undergoes a Bardeen-Cooper-Schrieffer (BCS) to a Bose-Einstein Condensate (BEC) crossover as a function of $\ln (k_F a)$, where $a$ is…

Quantum Gases · Physics 2026-02-27 S. Ramachandran , S. Jensen , Y. Alhassid

The viscous and thermal relaxation rates of an interacting fermion gas are calculated as functions of temperature and scattering length, using a many-body scattering matrix which incorporates medium effects due to Fermi blocking of…

Statistical Mechanics · Physics 2009-11-11 G. M. Bruun , H. Smith

We study the Higgs mode of a strongly-interacting Fermi gas in the crossover regime between a fermionic and bosonic superfluid. By periodically modulating the interaction strength of the gas, we parametrically excite the Higgs mode and…

Quantum Gases · Physics 2024-10-15 Andreas Kell , Moritz Breyer , Daniel Eberz , Michael Köhl

An expression for the dynamic density response function has been obtained for an interacting quantum gas in Random Phase Approximation (RPA) including first order self and exchange contribution. It involves the single particle wave…

Quantum Gases · Physics 2015-05-30 Renu Bala , J. Bosse , K. N. Pathak

We use the virial expansion to investigate the behavior of the two-component, attractive Fermi gas in the high-temperature limit, where the system smoothly evolves from weakly attractive fermions to weakly repulsive bosonic dimers as the…

Quantum Gases · Physics 2015-01-12 V. Ngampruetikorn , Meera M. Parish , Jesper Levinsen

The virial expansion characterizes the high-temperature approach to the quantum-classical crossover in any quantum many-body system. Here, we calculate the virial coefficients up to the fifth-order of Fermi gases in 1D, 2D, and 3D, with…

Quantum Gases · Physics 2020-09-16 Y. Hou , J. E. Drut

We study the response of a single-component pair-correlated baryonic Fermi-liquid to density, spin, and their current perturbations. A complete set of response functions is derived in the low-temperature regime both within an effective…

Nuclear Theory · Physics 2013-04-25 Jochen Keller , Armen Sedrakian

Recent breakthroughs in the creation of ultra-cold atomic gases in the laboratory have ushered in major changes in physical science. Many novel experiments are now possible, with an unprecedented control of interaction, geometry and purity.…

Quantum Gases · Physics 2014-11-13 Hui Hu

The Higgs boson in fermionic condensates with the BCS pairing interaction describes the dynamics of the pairing amplitude. I show that the existence and properties of this mode are sensitive to the energy dispersion of the interaction.…

Superconductivity · Physics 2008-12-31 Roman Barankov

For a fermion gas with equally spaced energy levels, the density and the pair correlation function are obtained. The derivation is based on the path integral approach for identical particles and the inversion of the generating functions for…

Statistical Mechanics · Physics 2009-10-31 F. Brosens , J. T. Devreese , L. F. Lemmens

We report the experimental measurement of the equation of state of a two-dimensional Fermi gas with attractive s-wave interactions throughout the crossover from a weakly coupled Fermi gas to a Bose gas of tightly bound dimers as the…

Quantum Gases · Physics 2016-02-02 I. Boettcher , L. Bayha , D. Kedar , P. A. Murthy , M. Neidig , M. G. Ries , A. N. Wenz , G. Zürn , S. Jochim , T. Enss

The strongly attractive Fermi gas in the BCS-BEC crossover is efficiently described in terms of coupled fermions and fermion pairs, or molecules. We compute the spectral functions of both fermions and pairs in the normal state near the…

Quantum Gases · Physics 2024-03-01 Tilman Enss

We present an experimental study of a two component Fermi gas following an interaction quench into the superfluid phase. Starting with a weakly attractive gas in the normal phase, interactions are ramped to unitarity at a range of rates and…

Quantum Gases · Physics 2021-09-08 P. Dyke , A. Hogan , I. Herrera , C. C. N. Kuhn , S. Hoinka , C. J. Vale

We perform a variational quantum Monte Carlo simulation of an interacting Fermi gas confined in a three dimensional harmonic potential. This gas is considered as the precursor system from which a molecular bosonic gas is formed. Based on…

Other Condensed Matter · Physics 2009-11-11 R. Jauregui , R. Paredes , G. Toledo Sanchez

Spin fluctuations and density fluctuations are studied for a two-component gas of strongly interacting fermions along the BEC-BCS crossover. This is done by in-situ imaging of dispersive speckle patterns. Compressibility and magnetic…

We construct systematic expansions around four and two spatial dimensions for a Fermi gas near the unitarity limit. Near four spatial dimensions such a Fermi gas can be understood as a weakly interacting system of fermionic and bosonic…

Other Condensed Matter · Physics 2009-02-05 Yusuke Nishida , Dam Thanh Son