Observation of pair condensation in the quasi-2D BEC-BCS crossover

Abstract

The condensation of fermion pairs lies at the heart of superfluidity. However, for strongly correlated systems with reduced dimensionality the mechanisms of pairing and condensation are still not fully understood. In our experiment we use ultracold atoms as a generic model system to study the phase transition from a normal to a condensed phase in a strongly interacting quasi-two-dimensional Fermi gas. Using a novel method, we obtain the in situ pair momentum distribution of the strongly interacting system and observe the emergence of a low-momentum condensate at low temperatures. By tuning temperature and interaction strength we map out the phase diagram of the quasi-2D BEC-BCS crossover.

References in corpus (14)

• Many-Body Physics with Ultracold Gases
• Vortices and Superfluidity in a Strongly Interacting Fermi Gas
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Attractive and repulsive Fermi polarons in two dimensions
• Observation of scale invariance and universality in two-dimensional Bose gases
• Radiofrequency spectroscopy of a strongly interacting two-dimensional Fermi gas
• Strong saturation absorption imaging of dense clouds of ultracold atoms
• Superfluid behaviour of a two-dimensional Bose gas
• Observation of a two-dimensional Fermi gas of atoms
• Crossover from 2D to 3D in a weakly interacting Fermi gas
• Improved detection of small atom numbers through image processing
• Matter wave Fourier optics with a strongly interacting two-dimensional Fermi gas
• Quasi-two-dimensional Fermi gases at finite temperature
• Pseudogap phenomena in a two-dimensional ultracold Fermi gas near the Berezinskii-Kosterlitz-Thouless transition

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• Spin-Imbalanced Quasi-Two-Dimensional Fermi Gases
• Loading and compression of a single two-dimensional Bose gas in an optical accordion
• Connecting Berezinskii-Kosterlitz-Thouless and BEC phase transitions by tuning interactions in a trapped gas
• When Superconductivity Crosses Over: From BCS to BEC
• Nonperturbative renormalization group treatment of amplitude fluctuations for $|\phi {|}^4$ topological phase transitions
• Visualizing the BEC-BCS crossover in the two-dimensional Fermi gas: pairing gaps and dynamical response functions from ab initio computations
• Measuring pair correlations in Bose and Fermi gases via atom-resolved microscopy
• Dynamical structure factors of a two-dimensional Fermi superfluid within random phase approximation
• Quartet Superfluid in Two-dimensional Mass-imbalanced Fermi Mixtures
• BCS-BEC crossover of atomic Fermi superfluid in a spherical bubble trap
• Andreev reflection spectroscopy in strongly paired superconductors
• Precision Many-Body Study of the Berezinskii-Kosterlitz-Thouless Transition and Temperature-Dependent Properties in the Two-Dimensional Fermi Gas
• Superconductivity induced by strong electron-exciton coupling in doped atomically thin semiconductor heterostructures
• Enhancing $T_{\mathrm{c}}$ in a composite superconductor/metal bilayer system: a dynamical cluster approximation study
• Josephson effect with superfluid fermions in the two-dimensional BCS-BEC crossover
• Thermodynamic equivalence of two-dimensional imperfect attractive Fermi and repulsive Bose gases
• Berezinskii-Kosterlitz-Thouless phase transition with Rabi-coupled bosons
• Mobile impurity probing a two-dimensional superfluid phase transition
• Interaction and coherence in 2D bilayers
• Density correlation functions and the spatial structure of the two-dimensional BEC-BCS crossover
• What can we learn from diffusion about Anderson localization of a degenerate Fermi gas?
• Quantum fluctuations and vortex-antivortex unbinding in the 2D BCS-BEC crossover
• Brueckner $G$-matrix approach to two-dimensional Fermi gases with the finite-range attractive interaction
• Kosterlitz-Thouless transition and vortex-antivortex lattice melting in two-dimensional Fermi gases with $p$- or $d$-wave pairing
• Dynamical effects on superconductivity in BCS-BEC crossover
• Ground states of atomic Fermi gases in a two-dimensional optical lattice with and without population imbalance
• Pseudogap regime of a two-dimensional uniform Fermi gas
• Interplay between Rashba spin-orbit coupling and adiabatic rotation in a two-dimensional Fermi gas
• Pseudogap phenomena near the BKT transition of a two-dimensional ultracold Fermi gas in the crossover region
• Observing Spatial Charge and Spin Correlations in a Strongly-Interacting Fermi Gas
• Quantum Monte Carlo study of the metal-insulator crossover in the square-lattice Hubbard model
• First and second sound in two-dimensional bosonic and fermionic superfluids
• Triplet character of 2D-fermion dimers arising from $s$-wave attraction via spin-orbit coupling and Zeeman splitting
• Non-universal Fermi polaron in quasi two-dimensional quantum gases
• The normal state of attractive Fermi gases from coupled-cluster theory
• Precision thermodynamics of the strongly interacting Fermi gas in two dimensions
• BCS-BEC crossover in a quasi-two-dimensional Fermi superfluid
• Composite Bosons Superposition Ansatz Approach to One-Dimensional Trapped Few-Fermion Systems
• Strong Fulde-Ferrell Larkin-Ovchinnikov pairing fluctuations in polarized Fermi systems