Observation of Pair Condensation in the Quasi-2D BEC-BCS Crossover

2014/09/30 by M. G. Ries, A. N. Wenz, G. Zürn +13 · 169 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Condensation #Condensed matter physics #Cooper pair #Crossover #Fermi Gamma-ray Space Telescope #Fermion #Momentum (technical analysis) #Pairing #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum mechanics #Quantum, superfluid, helium dynamics #Superconductivity #Superfluidity #Thermodynamics #Ultracold atom #cond-mat.quant-gas

paper · pdf · doi:10.1103/physrevlett.114.230401

published in Physical Review Letters 114(23), 230401 (American Physical Society)

openalex publication_date 2015/06/08 · arxiv created 2015/06/10 · arxiv updated 2015/06/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

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.

Citations

• Many-body physics with ultracold gases
• Existence of Long-Range Order in One and Two Dimensions
• Observation of resonance condensation of fermionic atom pairs
• Absence of Ferromagnetism or Antiferromagnetism in One- or Two-Dimensional Isotropic Heisenberg Models
• The Challenge of Unconventional Superconductivity
• Vortices and superfluidity in a strongly interacting Fermi gas
• Collective Excitations of a Degenerate Gas at the BEC-BCS Crossover
• Berezinskii–Kosterlitz–Thouless crossover in a trapped atomic gas
• Ordering, metastability and phase transitions in two-dimensional systems
• Quasicondensation and coherence in the quasi-two-dimensional trapped Bose gas

Cited by

• Strong pairing in two dimensions: pseudogaps, domes, and other implications
• Topological superfluids on a square optical lattice with non-Abelian gauge fields: Effects of next-nearest-neighbor hopping in the BCS-BEC evolution