Spin-Imbalanced Quasi-Two-Dimensional Fermi Gases

Abstract

We measure the density profiles for a Fermi gas of ${}^6$Li containing $N_1$ spin-up atoms and $N_2$ spin-down atoms, confined in a quasi-two-dimensional geometry. The spatial profiles are measured as a function of spin-imbalance $N_2/N_1$ and interaction strength, which is controlled by means of a collisional (Feshbach) resonance. The measured cloud radii and central densities are in disagreement with mean-field Bardeen-Cooper-Schrieffer theory for a true two-dimensional system. We find that the data for normal-fluid mixtures are reasonably well fit by a simple two-dimensional polaron model of the free energy. Not predicted by the model is a phase transition to a spin-balanced central core, which is observed above a critical value of $N_2/N_1$. Our observations provide important benchmarks for predictions of the phase structure of quasi-two-dimensional Fermi gases.

arXiv comment14 pages, 12 figures

References in corpus (59)

• Many-Body Physics with Ultracold Gases
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Feshbach Resonances in Ultracold Gases
• Observation of a Strongly-Interacting Degenerate Fermi Gas of Atoms
• Pairing and Phase Separation in a Polarized Fermi Gas
• Fermionic Superfluidity with Imbalanced Spin Populations and the Quantum Phase Transition to the Normal State
• Magnetism, superconductivity, and pairing symmetry in Fe-based superconductors
• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Spin-Imbalance in a One-Dimensional Fermi Gas
• Attractive and repulsive Fermi polarons in two dimensions
• Interatomic collisions in a tightly confined Bose gas
• The Challenge of Unconventional Superconductivity
• Observation of Phase Separation in a Strongly-Interacting Imbalanced Fermi Gas
• Universal phase diagram of a strongly interacting Fermi gas with unbalanced spin populations
• Heat Capacity of a Strongly-Interacting Fermi Gas
• Universal Quantum Viscosity in a Unitary Fermi Gas
• Phase diagram of a two-component Fermi gas with resonant interactions
• Precise determination of ${}^6$Li cold collision parameters by radio-frequency spectroscopy on weakly bound molecules
• BCS-BEC Crossover and the Unitary Fermi Gas
• Breathing Modes and Hidden Symmetry of Trapped Atoms in 2D
• Precise characterization of ^6Li Feshbach resonances using trap-sideband resolved RF spectroscopy of weakly bound molecules
• Trapped Fermi gases
• Observation of a pairing pseudogap in a two-dimensional Fermi gas
• The Superfluid State of Atomic Li6 in a Magnetic Trap
• Ultra-cold Polarized Fermi Gases
• Observation of a two-dimensional Fermi gas of atoms
• Evolution of Fermion Pairing from Three to Two Dimensions
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• BCS-BEC crossover in a two-dimensional Fermi gas
• Evidence of Andreev bound states as a hallmark of the FFLO phase in $\kappa$-(BEDT-TTF)${}_2$Cu(NCS)${}_2$
• Polarons in the radio-frequency spectrum of a quasi-two-dimensional Fermi gas
• Strongly interacting Fermi gases with density imbalance
• Ground-state pressure of quasi-2D Fermi and Bose gases
• Observation of Anomalous Spin Segregation in a Trapped Fermi Gas
• Highly polarized Fermi gases in two dimensions
• Vortex-Antivortex Lattice in Ultra-Cold Fermi Gases
• Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases
• Universal equation of state and pseudogap in the two-dimensional Fermi gas
• Super Efimov effect of resonantly interacting fermions in two dimensions
• Polarons and Molecules in a Two-Dimensional Fermi Gas
• Determination of the Equation of State of a Two-Component Fermi Gas at Unitarity
• Superfluidity at the BEC-BCS crossover in two-dimensional Fermi gases with population and mass imbalance
• Anomalous minimum in the shear viscosity of a Fermi gas
• Berezinskii-Kosterlitz-Thouless transition in trapped quasi-two-dimensional Fermi gas near a Feshbach resonance
• Pair Correlations in the Two-Dimensional Fermi Gas
• The effect of population imbalance on the Berezinskii-Kosterlitz-Thouless phase transition in a superfluid Fermi gas
• Phase Diagram of Cold Polarized Fermi Gas in Two Dimensions
• Density distribution of a trapped two-dimensional strongly interacting Fermi gas
• The Fermi-polaron in two dimensions: Importance of the two-body bound state
• Fulde-Ferrell states and Berezinskii-Kosterlitz-Thouless phase transition in two-dimensional imbalanced Fermi gases
• Pseudogap and preformed pairs in the imbalanced Fermi gas in two dimensions
• Pairing in a two-dimensional Fermi gas with population imbalance
• Quasi two-dimensional superfluid Fermi gases
• Fulde-Ferrell-Larkin-Ovchinnikov state of two-dimensional imbalanced Fermi gases
• A long-lived Higgs mode in a two-dimensional confined Fermi gas
• High-polarization limit of the quasi-two-dimensional Fermi gas
• Quasi-two-dimensional Fermi gases at finite temperature
• Finite Temperature Phase Diagram of Quasi-Two-Dimensional Imbalanced Fermi Gases Beyond Mean-Field
• Superfluidity in Two-Dimensional Imbalanced Fermi Gases

Cited by in corpus (65)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Two-Dimensional Homogeneous Fermi Gases
• Equation of State of Ultracold Fermions in the 2D BEC-BCS Crossover Region
• Quantum fluctuations in the BCS-BEC crossover of two-dimensional Fermi gases
• An ideal Josephson junction in an ultracold two-dimensional Fermi gas
• Pressure, compressibility, and contact of the two-dimensional attractive Fermi gas
• Observation of coherent multiorbital polarons in a two-dimensional Fermi gas
• Quasiparticle lifetime of the repulsive Fermi polaron
• Fate of the Bose polaron at finite temperature
• Observation of superfluidity in a strongly correlated two-dimensional Fermi gas
• Phase separation and pair condensation in a spin-imbalanced 2D Fermi gas
• Many-body interferometry of magnetic polaron dynamics
• Diffusion Monte Carlo study of strongly interacting two-dimensional Fermi gases
• Quantum anomaly and thermodynamics of one-dimensional fermions with three-body interactions
• Fermi-to-Bose crossover in a trapped quasi-2D gas of fermionic atoms
• Superfluid density and critical velocity near the fermionic Berezinskii-Kosterlitz-Thouless transition
• Dynamic density and spin responses of a superfluid Fermi gas in the BCS-BEC crossover: Path integral formulation and pair fluctuation theory
• Fermi Gases in the Two-Dimensional to Quasi-Two-Dimensional Crossover
• Ground state of the two-dimensional attractive Fermi gas: essential properties from few- to many-body
• Visualizing the BEC-BCS crossover in the two-dimensional Fermi gas: pairing gaps and dynamical response functions from ab initio computations
• Unconventional superconductivity in low density electron systems and conventional superconductivity in hydrogen metallic alloys under pressure
• FFLO strange metal and quantum criticality in two dimensions: theory and application to organic superconductors
• Effect of fermion indistinguishability on optical absorption of doped two-dimensional semiconductors
• Pseudopotential for the 2D contact interaction
• Fermi-Fermi crossover in the ground state of 1D few-body systems with anomalous three-body interactions
• Larkin-Ovchinnikov superfluidity in a two-dimensional imbalanced atomic Fermi gas
• Dimensional crossover in a strongly interacting ultracold atomic Fermi gas
• Universal Properties of Fermi Gases in One-dimension
• Thermodynamics and static response of anomalous 1D fermions via quantum Monte Carlo in the worldline representation
• Dimensional Crossover in a Spin-imbalanced Fermi gas
• Fermi polaron in low-density spin-polarized neutron matter
• Breathing mode frequency of a strongly interacting Fermi gas across the 2D-3D dimensional crossover
• Effects of quantum fluctuations on the low-energy collective modes of two-dimensional superfluid Fermi gases from the BCS to the Bose Limit
• A Quantum Field-Theoretical Perspective on Scale Anomalies in 1D systems with Three-Body Interactions
• Rabi oscillations and magnetization of a mobile spin-1/2 impurity in a Fermi sea
• Fermions in Two Dimensions: Scattering and Many-Body Properties
• Thermodynamic equivalence of two-dimensional imperfect attractive Fermi and repulsive Bose gases
• Variational approach to the two-dimensional Bose polaron
• Effective potential and quantum criticality for imbalanced Fermi mixtures
• Harmonically trapped fermions in two dimensions: ground-state energy and contact of SU(2) and SU(4) systems via nonuniform lattice Monte Carlo
• Equation of state and Kosterlitz-Thouless transition temperature in two-dimensional Fermi gases: An analytical approach
• Pairing in two-dimensional Fermi gases with a coordinate-space potential
• Unusual destruction and enhancement of superfluidity of atomic Fermi gases by population imbalance in a one-dimensional optical lattice
• Formation of droplets of the order parameter and superconductivity in inhomogeneous Fermi-Bose mixtures (Brief review)
• Finite-range effects in the two-dimensional repulsive Fermi polaron
• Dimensional crossover in ultracold Fermi gases from Functional Renormalisation
• Non-relativistic trace anomaly and equation of state in dense fermionic matter
• Higher-Harmonic Collective Modes in a Trapped Gas from Second-Order Hydrodynamics
• Anomalous superconductivity and superfluidity in repulsive fermion systems
• Kosterlitz-Thouless transition and vortex-antivortex lattice melting in two-dimensional Fermi gases with $p$- or $d$-wave pairing
• Probing polaron clouds by Rydberg atom spectroscopy
• Two-dimensional Fermi gas in antiparallel magnetic fields
• Ground states of atomic Fermi gases in a two-dimensional optical lattice with and without population imbalance
• Superfluidity and pairing phenomena in ultracold atomic Fermi gases in one-dimensional optical lattices, Part II: Effects of population imbalance
• Two-dimensional spin-imbalanced Fermi gases at non-zero temperature: Phase separation of a non-condensate
• Damping of the Anderson-Bogolyubov mode by spin and mass imbalance in Fermi mixtures
• Repulsive Fermi and Bose Polarons in Quantum Gases
• Quantum anomaly and thermodynamics of one-dimensional fermions with antisymmetric two-body interactions
• Medium-enhanced polaron repulsion in a dilute Bose mixture
• Momentum distribution of Cooper-pairs and strong-coupling effects in a two-dimensional Fermi gas near the Berezinskii-Kosterlitz-Thouless transition
• Superfluid-Normal Quantum Phase Transitions in an Imbalanced Fermi Gas
• Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting
• Signatures of the orthogonality catastrophe in a coherently driven impurity
• Properties of a static dipolar impurity in a 2D dipolar BEC
• Repulsive fermions and shell effects on the surface of a sphere