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Dupont N, Gabardos L, Arrouas F, Chatelain G, Arnal M, Billy J, Schlagheck P, Peaudecerf B, Guéry-Odelin D. Emergence of tunable periodic density correlations in a Floquet-Bloch system. Proc Natl Acad Sci U S A 2023; 120:e2300980120. [PMID: 37527345 PMCID: PMC10410701 DOI: 10.1073/pnas.2300980120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/16/2023] [Indexed: 08/03/2023] Open
Abstract
In quantum gases, two-body interactions are responsible for a variety of instabilities that depend on the characteristics of both trapping and interactions. These instabilities can lead to the appearance of new structures or patterns. We report on the Floquet engineering of such a parametric instability, on a Bose-Einstein condensate held in a time-modulated optical lattice. The modulation triggers a destabilization of the condensate into a state exhibiting a density modulation with a new spatial periodicity. This new crystal-like order, which shares characteristic correlation properties with a supersolid, directly depends on the modulation parameters: The interplay between the Floquet spectrum and interactions generates narrow and adjustable instability regions, leading to the growth, from quantum or thermal fluctuations, of modes with a density modulation noncommensurate with the lattice spacing. This study demonstrates the production of metastable exotic states of matter through Floquet engineering and paves the way for further studies of dissipation in the resulting phase and of similar phenomena in other geometries.
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Affiliation(s)
- Nathan Dupont
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Lucas Gabardos
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Floriane Arrouas
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Gabriel Chatelain
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Maxime Arnal
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Juliette Billy
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - Peter Schlagheck
- Complex and Entangled Systems from Atoms to Materials Research Unit, University of Liège, 4000Liège, Belgium
| | - Bruno Peaudecerf
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
| | - David Guéry-Odelin
- Laboratoire Collisions Agrégats Réactivité, UMR 5589, Fédération de Recherche Matière et Interactions, Université Toulouse 3, CNRS, Toulouse, CEDEX 0931062, France
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Observation of Cooper pairs in a mesoscopic two-dimensional Fermi gas. Nature 2022; 606:287-291. [PMID: 35676427 DOI: 10.1038/s41586-022-04678-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/23/2022] [Indexed: 11/08/2022]
Abstract
The formation of strongly correlated fermion pairs is fundamental for the emergence of fermionic superfluidity and superconductivity1. For instance, Cooper pairs made of two electrons of opposite spin and momentum at the Fermi surface of the system are a key ingredient of Bardeen-Cooper-Schrieffer (BCS) theory-the microscopic explanation of the emergence of conventional superconductivity2. Understanding the mechanism behind pair formation is an ongoing challenge in the study of many strongly correlated fermionic systems3. Controllable many-body systems that host Cooper pairs would thus be desirable. Here we directly observe Cooper pairs in a mesoscopic two-dimensional Fermi gas. We apply an imaging scheme that enables us to extract the full in situ momentum distribution of a strongly interacting Fermi gas with single-particle and spin resolution4. Our ultracold gas enables us to freely tune between a completely non-interacting, unpaired system and weak attractions, where we find Cooper pair correlations at the Fermi surface. When increasing the attractive interactions even further, the pairs gradually turn into deeply bound molecules that break up the Fermi surface. Our mesoscopic system is closely related to the physics of nuclei, superconducting grains or quantum dots5-7. With the precise control over the interactions, particle number and potential landscape in our experiment, the observables we establish in this work provide an approach for answering longstanding questions concerning not only such mesoscopic systems but also their connection to the macroscopic world.
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