Yean-an Liao1,4, Ann Sophie C. Rittner1,4, Tobias Paprotta1, Wenhui Li1,3, Guthrie B. Partridge1,5, Randall G. Hulet1, Stefan K. Baur2 & Erich J. Mueller2
- Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77251, USA
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore
- These authors contributed equally to this work.
- Present address: Laboratoire Charles Fabry de l’Institut d’Optique, UMR CNRS 8501, Palaiseau, France.
Correspondence to: Randall G. Hulet1 Email: randy@rice.edu
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Abstract
Superconductivity and magnetism generally do not coexist. Changing the relative number of up and down spin electrons disrupts the basic mechanism of superconductivity, where atoms of opposite momentum and spin form Cooper pairs. Nearly forty years ago Fulde and Ferrell1 and Larkin and Ovchinnikov2 (FFLO) proposed an exotic pairing mechanism in which magnetism is accommodated by the formation of pairs with finite momentum. Despite intense theoretical and experimental efforts, however, polarized superconductivity remains largely elusive3. Unlike the three-dimensional (3D) case, theories predict that in one dimension (1D) a state with FFLO correlations occupies a major part of the phase diagram4, 5, 6, 7, 8, 9, 10, 11, 12. Here we report experimental measurements of density profiles of a two-spin mixture of ultracold 6Li atoms trapped in an array of 1D tubes (a system analogous to electrons in 1D wires). At finite spin imbalance, the system phase separates with an inverted phase profile, as compared to the 3D case. In 1D, we find a partially polarized core surrounded by wings which, depending on the degree of polarization, are composed of either a completely paired or a fully polarized Fermi gas. Our work paves the way to direct observation and characterization of FFLO pairing.
- Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77251, USA
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore
- These authors contributed equally to this work.
- Present address: Laboratoire Charles Fabry de l’Institut d’Optique, UMR CNRS 8501, Palaiseau, France.
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