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Milner AA, Milner V. Controlled Excitation of Rotons in Superfluid Helium with an Optical Centrifuge. PHYSICAL REVIEW LETTERS 2023; 131:166001. [PMID: 37925729 DOI: 10.1103/physrevlett.131.166001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/12/2023] [Accepted: 09/20/2023] [Indexed: 11/07/2023]
Abstract
We experimentally demonstrate a controlled transfer of angular momentum to roton pairs in superfluid helium. The control is executed with an optical centrifuge and detected with coherent time- and frequency-resolved Raman scattering. We show that the sign of the Raman shift, and hence the orientation of the angular momentum transferred from the laser field to the rotons, is dictated by the centrifuge. The magnitude of the shift reflects the two-roton energy and indicates that the centrifuge-induced roton pairs are far from the equilibrium with the quantum bath. The observed decay of the coherent Raman signal suggests that the decoherence is governed by the scattering on thermal rotons and phonons. The demonstrated method offers ways of examining microscopic origins of superfluidity by controlling collective excitations in superfluids.
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Affiliation(s)
- Alexander A Milner
- Department of Physics & Astronomy, The University of British Columbia, V6T 2K9, Vancouver, Canada
| | - Valery Milner
- Department of Physics & Astronomy, The University of British Columbia, V6T 2K9, Vancouver, Canada
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Dornheim T, Moldabekov ZA, Vorberger J, Militzer B. Path integral Monte Carlo approach to the structural properties and collective excitations of liquid [Formula: see text] without fixed nodes. Sci Rep 2022; 12:708. [PMID: 35027602 PMCID: PMC8758733 DOI: 10.1038/s41598-021-04355-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/21/2021] [Indexed: 11/10/2022] Open
Abstract
Due to its nature as a strongly correlated quantum liquid, ultracold helium is characterized by the nontrivial interplay of different physical effects. Bosonic [Formula: see text] exhibits superfluidity and Bose-Einstein condensation. Its physical properties have been accurately determined on the basis of ab initio path integral Monte Carlo (PIMC) simulations. In contrast, the corresponding theoretical description of fermionic [Formula: see text] is severely hampered by the notorious fermion sign problem, and previous PIMC results have been derived by introducing the uncontrolled fixed-node approximation. In this work, we present extensive new PIMC simulations of normal liquid [Formula: see text] without any nodal constraints. This allows us to to unambiguously quantify the impact of Fermi statistics and to study the effects of temperature on different physical properties like the static structure factor [Formula: see text], the momentum distribution [Formula: see text], and the static density response function [Formula: see text]. In addition, the dynamic structure factor [Formula: see text] is rigorously reconstructed from imaginary-time PIMC data. From simulations of [Formula: see text], we derived the familiar phonon-maxon-roton dispersion function that is well-known for [Formula: see text] and has been reported previously for two-dimensional [Formula: see text] films (Nature 483:576-579 (2012)). The comparison of our new results for both [Formula: see text] and [Formula: see text] with neutron scattering measurements reveals an excellent agreement between theory and experiment.
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Affiliation(s)
- Tobias Dornheim
- Center for Advanced Systems Understanding (CASUS), 02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany
| | - Zhandos A. Moldabekov
- Center for Advanced Systems Understanding (CASUS), 02826 Görlitz, Germany
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany
| | - Jan Vorberger
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany
| | - Burkhard Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720 USA
- Department of Astronomy, University of California, Berkeley, CA 94720 USA
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The First Two Decades of Neutron Scattering at the Chalk River Laboratories. QUANTUM BEAM SCIENCE 2021. [DOI: 10.3390/qubs5010003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The early advances in neutron scattering at the Chalk River Laboratories of Atomic Energy of Canada are recorded. From initial nuclear physics measurements at the National Research Experimental (NRX) reactor came the realization that, with the flux available and improvements in monochromator technology, direct measurements of the normal modes of vibrations of solids and the structure and dynamics of liquids would be feasible. With further flux increases at the National Research Universal (NRU) reactor, the development of the triple-axis crystal spectrometer, and the invention of the constant-Q technique, the fields of lattice dynamics and magnetism and their interpretation in terms of the long-range forces between atoms and exchange interactions between spins took a major step forward. Experiments were performed over a seven-year period on simple metals such as potassium, complex metals such as lead, transition metals, semiconductors, and alkali halides. These were analyzed in terms of the atomic forces and demonstrated the long-range nature of the forces. The first measurements of spin wave excitations, in magnetite and in the 3D metal alloy CoFe, also came in this period. The first numerical estimates of the superfluid fraction of liquid helium II came from extensive measurements of the phonon–roton and multiphonon parts of the inelastic scattering. After the first two decades, neutron experiments continued at Chalk River until the shut-down of the NRU reactor in 2018 and the disbanding of the neutron effort in 2019, seventy years after the first experiments.
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Glyde HR. Quantum liquids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:374002. [PMID: 31226701 DOI: 10.1088/1361-648x/ab2ba6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/21/2019] [Indexed: 06/09/2023]
Abstract
This article is dedicated to Roger A Cowley and his seminal contributions to our understanding of quantum liquids, both liquid4He and3He. Roger Cowley's neutron scattering measurements of the collective and independent particle response of liquid4He were made at Chalk River Laboratories in 1965-74 chiefly with A D B (Dave) Woods. They measured the phonon-roton (P-R) mode energy, intensity and width with new precision. Particularly, they extended the measurements to higher wave vector and identified both collective and single particle response regimes. They showed that the P-R mode terminated at a finite energy as predicted by Pitaeskii rather than continuing as predicted by Feynman and Feynman and Cohen. They determined both the single P-R mode and multimode contributions to the dynamics. They made direct comparison with theory which Roger understood well. They observed the Bose-Einstein condensate (BEC) fraction in liquid4He for the first time. This appears to be the first ever observation of BEC in any Bose gas or liquid. Roger Cowley's pioneering measurements of the density excitations of liquid3He were made at the Institut Laue Langevin (ILL) in the period 1973-80. Roger, Reinhard Scherm, W G (Bill) Stirling and collaborators showed for the first time that the density response of this highly neutron absorbing liquid could indeed be observed with neutrons. They documented with others the dynamic response as a function of temperature and pressure stimulating extensive theoretical and experimental interest that continues today.
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Affiliation(s)
- H R Glyde
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716-2593, United States of America
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Lopes R, Eigen C, Barker A, Viebahn KGH, Robert-de-Saint-Vincent M, Navon N, Hadzibabic Z, Smith RP. Quasiparticle Energy in a Strongly Interacting Homogeneous Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2017; 118:210401. [PMID: 28598671 DOI: 10.1103/physrevlett.118.210401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 06/07/2023]
Abstract
Using two-photon Bragg spectroscopy, we study the energy of particlelike excitations in a strongly interacting homogeneous Bose-Einstein condensate, and observe dramatic deviations from Bogoliubov theory. In particular, at large scattering length a the shift of the excitation resonance from the free-particle energy changes sign from positive to negative. For an excitation with wave number q, this sign change occurs at a≈4/(πq), in agreement with the Feynman energy relation and the static structure factor expressed in terms of the two-body contact. For a≳3/q we also see a breakdown of this theory, and better agreement with calculations based on the Wilson operator product expansion. Neither theory explains our observations across all interaction regimes, inviting further theoretical efforts.
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Affiliation(s)
- Raphael Lopes
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Christoph Eigen
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Adam Barker
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Konrad G H Viebahn
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | | | - Nir Navon
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Zoran Hadzibabic
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Robert P Smith
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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Affiliation(s)
- F. J. Webb
- Atomic Energy Research Establishment, Harwell, England
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Observation of dynamic atom-atom correlation in liquid helium in real space. Nat Commun 2017; 8:15294. [PMID: 28469252 PMCID: PMC5418607 DOI: 10.1038/ncomms15294] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 03/17/2017] [Indexed: 11/09/2022] Open
Abstract
Liquid 4He becomes superfluid and flows without resistance below temperature 2.17 K. Superfluidity has been a subject of intense studies and notable advances were made in elucidating the phenomenon by experiment and theory. Nevertheless, details of the microscopic state, including dynamic atom–atom correlations in the superfluid state, are not fully understood. Here using a technique of neutron dynamic pair-density function (DPDF) analysis we show that 4He atoms in the Bose–Einstein condensate have environment significantly different from uncondensed atoms, with the interatomic distance larger than the average by about 10%, whereas the average structure changes little through the superfluid transition. DPDF peak not seen in the snap-shot pair-density function is found at 2.3 Å, and is interpreted in terms of atomic tunnelling. The real space picture of dynamic atom–atom correlations presented here reveal characteristics of atomic dynamics not recognized so far, compelling yet another look at the phenomenon. Liquid helium can be treated as an ideal gas or a condensed liquid and displays intriguing features like Bose–Einstein condensation. Here the authors show that roton excitation reveals information on real space dynamic atom-atom correlations in superfluid helium, which could be used to benchmark models.
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Bramwell ST, Keimer B. Neutron scattering from quantum condensed matter. NATURE MATERIALS 2014; 13:763-767. [PMID: 25191684 DOI: 10.1038/nmat4045] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
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Kukushkin IV, Smet JH, Scarola VW, Umansky V, von Klitzing K. Dispersion of the Excitations of Fractional Quantum Hall States. Science 2009; 324:1044-7. [DOI: 10.1126/science.1171472] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Igor V. Kukushkin
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
- Institute of Solid State Physics, Russian Academy of Science, Chernogolovka 142432, Russia
| | - Jurgen H. Smet
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | - Vito W. Scarola
- Department of Chemistry and Pitzer Center for Theoretical Chemistry, University of California at Berkeley, Berkeley, CA 94720, USA
- Theoretische Physik, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - Vladimir Umansky
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Klaus von Klitzing
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
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Yoshiki H, Sakai K, Ogura M, Kawai T, Masuda Y, Nakajima T, Takayama T, Tanaka S, Yamaguchi A. Observation of ultracold-neutron production by 9-Å cold neutrons in superfluid helium. PHYSICAL REVIEW LETTERS 1992; 68:1323-1326. [PMID: 10046137 DOI: 10.1103/physrevlett.68.1323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Talbot EF, Glyde HR, Stirling WG, Svensson EC. Temperature dependence of S(Q, omega ) in liquid 4He under pressure. PHYSICAL REVIEW. B, CONDENSED MATTER 1988; 38:11229-11244. [PMID: 9946000 DOI: 10.1103/physrevb.38.11229] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Tanatar B, Talbot EF, Glyde HR. Dynamics of quantum liquids at high momentum. PHYSICAL REVIEW. B, CONDENSED MATTER 1987; 36:8376-8392. [PMID: 9942655 DOI: 10.1103/physrevb.36.8376] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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13. Solid and Liquid Helium. ACTA ACUST UNITED AC 1987. [DOI: 10.1016/s0076-695x(08)60573-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Brown GV, Coopersmith MH. Excitation Spectrum for a Bose Gas with Repulsive Core and Attractive Well. ACTA ACUST UNITED AC 1969. [DOI: 10.1103/physrev.178.327] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Whitney WM, Chase CE. Ultrasonic Velocity and Dispersion in Liquid Helium II from 0.15 to 1.8°K. ACTA ACUST UNITED AC 1967. [DOI: 10.1103/physrev.158.200] [Citation(s) in RCA: 46] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Springett BE. Effects of Pressure on the Transport of Ions through Rotating Helium II. ACTA ACUST UNITED AC 1967. [DOI: 10.1103/physrev.155.139] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Henshaw DG, Woods ADB. Modes of Atomic Motions in Liquid Helium by Inelastic Scattering of Neutrons. ACTA ACUST UNITED AC 1961. [DOI: 10.1103/physrev.121.1266] [Citation(s) in RCA: 343] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Buckingham M, Fairbank W. Chapter III The Nature of the λ-Transition in Liquid Helium. ACTA ACUST UNITED AC 1961. [DOI: 10.1016/s0079-6417(08)60134-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Henshaw DG. Effect of theλTransition on the Atomic Distribution in Liquid Helium by Neutron Diffraction. ACTA ACUST UNITED AC 1960. [DOI: 10.1103/physrev.119.9] [Citation(s) in RCA: 96] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Cohen M. Relation between Inelastic Neutron Scattering and Thermodynamic Functions of Liquid Helium. ACTA ACUST UNITED AC 1960. [DOI: 10.1103/physrev.118.27] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Bendt PJ, Cowan RD, Yarnell JL. Excitations in Liquid Helium: Thermodynamic Calculations. ACTA ACUST UNITED AC 1959. [DOI: 10.1103/physrev.113.1386] [Citation(s) in RCA: 125] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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