1
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Biagioni G, Antolini N, Donelli B, Pezzè L, Smerzi A, Fattori M, Fioretti A, Gabbanini C, Inguscio M, Tanzi L, Modugno G. Measurement of the superfluid fraction of a supersolid by Josephson effect. Nature 2024; 629:773-777. [PMID: 38720083 PMCID: PMC11111407 DOI: 10.1038/s41586-024-07361-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 03/27/2024] [Indexed: 05/24/2024]
Abstract
A new class of superfluids and superconductors with spatially periodic modulation of the superfluid density is arising1-12. It might be related to the supersolid phase of matter, in which the spontaneous breaking of gauge and translational symmetries leads to a spatially modulated macroscopic wavefunction13-16. This relation was recognized only in some cases1,2,5-9 and there is the need for a universal property quantifying the differences between supersolids and ordinary matter, such as the superfluid fraction, which measures the reduction in superfluid stiffness resulting from the spatial modulation16-18. The superfluid fraction was introduced long ago16, but it has not yet been assessed experimentally. Here we demonstrate an innovative method to measure the superfluid fraction based on the Josephson effect, a ubiquitous phenomenon associated with the presence of a physical barrier between two superfluids or superconductors19, which might also be expected for supersolids20, owing to the spatial modulation. We demonstrate that individual cells of a supersolid can sustain Josephson oscillations and we show that, from the current-phase dynamics, we can derive directly the superfluid fraction. Our study of a cold-atom dipolar supersolid7 reveals a relatively large sub-unity superfluid fraction that makes realistic the study of previously unknown phenomena such as partially quantized vortices and supercurrents16-18. Our results open a new direction of research that may unify the description of all supersolid-like systems.
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Affiliation(s)
- G Biagioni
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Pisa, Pisa, Italy
| | - N Antolini
- CNR-INO, Sede di Pisa, Pisa, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
| | - B Donelli
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Firenze, Firenze, Italy
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy
- Università degli Studi di Napoli Federico II, Napoli, Italy
| | - L Pezzè
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Firenze, Firenze, Italy
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy
| | - A Smerzi
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy.
- CNR-INO, Sede di Firenze, Firenze, Italy.
- Quantum Science and Technology in Arcetri (QSTAR), Firenze, Italy.
| | - M Fattori
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- CNR-INO, Sede di Sesto Fiorentino, Sesto Fiorentino, Italy
| | | | | | - M Inguscio
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
- Dipartimento di Ingegneria, Università Campus Bio-Medico di Roma, Roma, Italy
| | - L Tanzi
- CNR-INO, Sede di Pisa, Pisa, Italy
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy
| | - G Modugno
- Dipartimento di Fisica e Astronomia, Università degli studi di Firenze, Sesto Fiorentino, Italy.
- CNR-INO, Sede di Pisa, Pisa, Italy.
- European Laboratory for Non-Linear Spectroscopy, Università degli studi di Firenze, Sesto Fiorentino, Italy.
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2
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Tao J, Zhao M, Spielman IB. Observation of Anisotropic Superfluid Density in an Artificial Crystal. PHYSICAL REVIEW LETTERS 2023; 131:163401. [PMID: 37925735 DOI: 10.1103/physrevlett.131.163401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 08/07/2023] [Indexed: 11/07/2023]
Abstract
We experimentally and theoretically investigate the anisotropic speed of sound of an atomic superfluid (SF) Bose-Einstein condensate in a 1D optical lattice. Because the speed of sound derives from the SF density, this implies that the SF density is itself anisotropic. We find that the speed of sound is decreased by the optical lattice, and the SF density is concomitantly reduced. This reduction is accompanied by the appearance of a zero entropy normal fluid in the purely Bose condensed phase. The reduction in SF density-first predicted [A. J. Leggett, Phys. Rev. Lett. 25, 1543 (1970).PRLTAO0031-900710.1103/PhysRevLett.25.1543] in the context of supersolidity-results from the coexistence of superfluidity and density modulations, but is agnostic about the origin of the modulations. We additionally measure the moment of inertia of the system in a scissors mode experiment, demonstrating the existence of rotational flow. As such we shed light on some supersolid properties using imposed, rather than spontaneously formed, density order.
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Affiliation(s)
- J Tao
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - M Zhao
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
| | - I B Spielman
- Joint Quantum Institute, University of Maryland and National Institute of Standards and Technology, College Park, Maryland 20742, USA
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3
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Chauveau G, Maury C, Rabec F, Heintze C, Brochier G, Nascimbene S, Dalibard J, Beugnon J, Roccuzzo SM, Stringari S. Superfluid Fraction in an Interacting Spatially Modulated Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2023; 130:226003. [PMID: 37327429 DOI: 10.1103/physrevlett.130.226003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/07/2023] [Accepted: 05/09/2023] [Indexed: 06/18/2023]
Abstract
At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity.
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Affiliation(s)
- G Chauveau
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - C Maury
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - F Rabec
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - C Heintze
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - G Brochier
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - S Nascimbene
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Dalibard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Beugnon
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - S M Roccuzzo
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Trento, Italy
| | - S Stringari
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Trento, Italy
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4
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Sánchez-Baena J, Politi C, Maucher F, Ferlaino F, Pohl T. Heating a dipolar quantum fluid into a solid. Nat Commun 2023; 14:1868. [PMID: 37015907 PMCID: PMC10073146 DOI: 10.1038/s41467-023-37207-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/06/2023] [Indexed: 04/06/2023] Open
Abstract
Raising the temperature of a material enhances the thermal motion of particles. Such an increase in thermal energy commonly leads to the melting of a solid into a fluid and eventually vaporises the liquid into a gaseous phase of matter. Here, we study the finite-temperature physics of dipolar quantum fluids and find surprising deviations from this general phenomenology. In particular, we describe how heating a dipolar superfluid from near-zero temperatures can induce a phase transition to a supersolid state with a broken translational symmetry. We discuss the observation of this effect in experiments on ultracold dysprosium atoms, which opens the door for exploring the unusual thermodynamics of dipolar quantum fluids.
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Affiliation(s)
- J Sánchez-Baena
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark.
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, 08034, Barcelona, Spain.
| | - C Politi
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
| | - F Maucher
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark
- Departament de Física, Universitat de les Illes Balears & IAC-3, Campus UIB, E-07122, Palma de Mallorca, Spain
| | - F Ferlaino
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
| | - T Pohl
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C, Denmark.
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5
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Chomaz L, Ferrier-Barbut I, Ferlaino F, Laburthe-Tolra B, Lev BL, Pfau T. Dipolar physics: a review of experiments with magnetic quantum gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 86:026401. [PMID: 36583342 DOI: 10.1088/1361-6633/aca814] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Since the achievement of quantum degeneracy in gases of chromium atoms in 2004, the experimental investigation of ultracold gases made of highly magnetic atoms has blossomed. The field has yielded the observation of many unprecedented phenomena, in particular those in which long-range and anisotropic dipole-dipole interactions (DDIs) play a crucial role. In this review, we aim to present the aspects of the magnetic quantum-gas platform that make it unique for exploring ultracold and quantum physics as well as to give a thorough overview of experimental achievements. Highly magnetic atoms distinguish themselves by the fact that their electronic ground-state configuration possesses a large electronic total angular momentum. This results in a large magnetic moment and a rich electronic transition spectrum. Such transitions are useful for cooling, trapping, and manipulating these atoms. The complex atomic structure and large dipolar moments of these atoms also lead to a dense spectrum of resonances in their two-body scattering behaviour. These resonances can be used to control the interatomic interactions and, in particular, the relative importance of contact over dipolar interactions. These features provide exquisite control knobs for exploring the few- and many-body physics of dipolar quantum gases. The study of dipolar effects in magnetic quantum gases has covered various few-body phenomena that are based on elastic and inelastic anisotropic scattering. Various many-body effects have also been demonstrated. These affect both the shape, stability, dynamics, and excitations of fully polarised repulsive Bose or Fermi gases. Beyond the mean-field instability, strong dipolar interactions competing with slightly weaker contact interactions between magnetic bosons yield new quantum-stabilised states, among which are self-bound droplets, droplet assemblies, and supersolids. Dipolar interactions also deeply affect the physics of atomic gases with an internal degree of freedom as these interactions intrinsically couple spin and atomic motion. Finally, long-range dipolar interactions can stabilise strongly correlated excited states of 1D gases and also impact the physics of lattice-confined systems, both at the spin-polarised level (Hubbard models with off-site interactions) and at the spinful level (XYZ models). In the present manuscript, we aim to provide an extensive overview of the various related experimental achievements up to the present.
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Affiliation(s)
- Lauriane Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - Igor Ferrier-Barbut
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127 Palaiseau, France
| | - Francesca Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - Bruno Laburthe-Tolra
- Université Sorbonne Paris Nord, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France
- CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - Benjamin L Lev
- Departments of Physics and Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA 94305, United States of America
| | - Tilman Pfau
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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6
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Steinberg AB, Maucher F, Gurevich SV, Thiele U. Exploring bifurcations in Bose-Einstein condensates via phase field crystal models. CHAOS (WOODBURY, N.Y.) 2022; 32:113112. [PMID: 36456347 DOI: 10.1063/5.0101401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/03/2022] [Indexed: 06/17/2023]
Abstract
To facilitate the analysis of pattern formation and the related phase transitions in Bose-Einstein condensates, we present an explicit approximate mapping from the nonlocal Gross-Pitaevskii equation with cubic nonlinearity to a phase field crystal (PFC) model. This approximation is valid close to the superfluid-supersolid phase transition boundary. The simplified PFC model permits the exploration of bifurcations and phase transitions via numerical path continuation employing standard software. While revealing the detailed structure of the bifurcations present in the system, we demonstrate the existence of localized states in the PFC approximation. Finally, we discuss how higher-order nonlinearities change the structure of the bifurcation diagram representing the transitions found in the system.
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Affiliation(s)
- A B Steinberg
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
| | - F Maucher
- Departament de Física, Universitat de les Illes Balears and IAC-3, Campus UIB, E-07122 Palma de Mallorca, Spain
| | - S V Gurevich
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
| | - U Thiele
- Institut für Theoretische Physik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
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7
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Norcia MA, Poli E, Politi C, Klaus L, Bland T, Mark MJ, Santos L, Bisset RN, Ferlaino F. Can Angular Oscillations Probe Superfluidity in Dipolar Supersolids? PHYSICAL REVIEW LETTERS 2022; 129:040403. [PMID: 35939003 DOI: 10.1103/physrevlett.129.040403] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/03/2022] [Accepted: 06/06/2022] [Indexed: 06/15/2023]
Abstract
Angular oscillations can provide a useful probe of the superfluid properties of a system. Such measurements have recently been applied to dipolar supersolids, which exhibit both density modulation and phase coherence, and for which robust probes of superfluidity are particularly interesting. So far, these investigations have been confined to linear droplet arrays, which feature relatively simple excitation spectra, but limited sensitivity to the effects of superfluidity. Here, we explore angular oscillations in systems with 2D structure which, in principle, have greater sensitivity to superfluidity. In both experiment and simulation, we find that the interplay of superfluid and crystalline excitations leads to a frequency of angular oscillations that remains nearly unchanged even when the superfluidity of the system is altered dramatically. This indicates that angular oscillation measurements do not always provide a robust experimental probe of superfluidity with typical experimental protocols.
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Affiliation(s)
- Matthew A Norcia
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
| | - Elena Poli
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Claudia Politi
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Lauritz Klaus
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Thomas Bland
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Manfred J Mark
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Luis Santos
- Institut für Theoretische Physik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | - Russell N Bisset
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
| | - Francesca Ferlaino
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck 6020, Austria
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck 6020, Austria
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8
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Hertkorn J, Schmidt JN, Guo M, Böttcher F, Ng KSH, Graham SD, Uerlings P, Büchler HP, Langen T, Zwierlein M, Pfau T. Supersolidity in Two-Dimensional Trapped Dipolar Droplet Arrays. PHYSICAL REVIEW LETTERS 2021; 127:155301. [PMID: 34678009 DOI: 10.1103/physrevlett.127.155301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/03/2021] [Indexed: 06/13/2023]
Abstract
We theoretically investigate the ground states and the spectrum of elementary excitations across the superfluid to droplet crystallization transition of an oblate dipolar Bose-Einstein condensate. We systematically identify regimes where spontaneous rotational symmetry breaking leads to the emergence of a supersolid phase with characteristic collective excitations, such as the Higgs amplitude mode. Furthermore, we study the dynamics across the transition and show how these supersolids can be realized with standard protocols in state-of-the-art experiments.
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Affiliation(s)
- J Hertkorn
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - J-N Schmidt
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M Guo
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - F Böttcher
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - K S H Ng
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - S D Graham
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - P Uerlings
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - H P Büchler
- Institute for Theoretical Physics III and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - T Langen
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M Zwierlein
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - T Pfau
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
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9
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Tanzi L, Maloberti JG, Biagioni G, Fioretti A, Gabbanini C, Modugno G. Evidence of superfluidity in a dipolar supersolid from nonclassical rotational inertia. Science 2021; 371:1162-1165. [PMID: 33602866 DOI: 10.1126/science.aba4309] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 02/02/2021] [Indexed: 11/02/2022]
Abstract
A key manifestation of superfluidity in liquids and gases is a reduction of the moment of inertia under slow rotations. Nonclassical rotational effects have also been considered in the context of the elusive supersolid phase of matter, in which superfluidity coexists with a lattice structure. Here, we show that the recently discovered supersolid phase in dipolar quantum gases features a reduced moment of inertia. Using a dipolar gas of dysprosium atoms, we studied a peculiar rotational oscillation mode in a harmonic potential, the scissors mode, previously investigated in ordinary superfluids. From the measured moment of inertia, we deduced a superfluid fraction that is different from zero and of order of unity, providing direct evidence of the superfluid nature of the dipolar supersolid.
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Affiliation(s)
- L Tanzi
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy.,LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - J G Maloberti
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy.,LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - G Biagioni
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy.,LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
| | - A Fioretti
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy
| | - C Gabbanini
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy
| | - G Modugno
- CNR-INO, Sede Secondaria di Pisa, 56124 Pisa, Italy. .,LENS and Dipartimento di Fisica e Astronomia, Università di Firenze, 50019 Sesto Fiorentino, Italy
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