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Wlazłowski G, Forbes MM, Sarkar SR, Marek A, Szpindler M. Fermionic quantum turbulence: Pushing the limits of high-performance computing. PNAS NEXUS 2024; 3:pgae160. [PMID: 38711809 PMCID: PMC11070604 DOI: 10.1093/pnasnexus/pgae160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Accepted: 03/29/2024] [Indexed: 05/08/2024]
Abstract
Ultracold atoms provide a platform for analog quantum computer capable of simulating the quantum turbulence that underlies puzzling phenomena like pulsar glitches in rapidly spinning neutron stars. Unlike other platforms like liquid helium, ultracold atoms have a viable theoretical framework for dynamics, but simulations push the edge of current classical computers. We present the largest simulations of fermionic quantum turbulence to date and explain the computing technology needed, especially improvements in the Eigenvalue soLvers for Petaflop Applications library that enable us to diagonalize matrices of record size (millions by millions). We quantify how dissipation and thermalization proceed in fermionic quantum turbulence by using the internal structure of vortices as a new probe of the local effective temperature. All simulation data and source codes are made available to facilitate rapid scientific progress in the field of ultracold Fermi gases.
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Affiliation(s)
- Gabriel Wlazłowski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
- Department of Physics, University of Washington, Seattle, WA 98195-1560, USA
| | - Michael McNeil Forbes
- Department of Physics, University of Washington, Seattle, WA 98195-1560, USA
- Department of Physics and Astronomy, Washington State University, Pullman, WA 99164, USA
| | - Saptarshi Rajan Sarkar
- Department of Physics and Astronomy, Washington State University, Pullman, WA 99164, USA
| | - Andreas Marek
- Max Planck Computing and Data Facility (MPCDF), 85741 Garching Near Munich, Germany
| | - Maciej Szpindler
- Academic Computer Centre CYFRONET, AGH University of Krakow, Ulica Nawojki 11, 30-950 Cracow, Poland
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Abstract
We report ab initio calculations of the S wave pairing gap in neutron matter calculated using realistic nuclear Hamiltonians that include two- and three-body interactions. We use a trial state, properly optimized to capture the essential pairing correlations, from which we extract ground state properties by means of auxiliary field diffusion Monte Carlo simulations. We extrapolate our results to the thermodynamic limit by studying the finite-size effects in the symmetry-restored projected Bardeen-Cooper-Schrieffer (PBCS) theory and compare our results to other ab initio studies done in the past. Our quantum Monte Carlo results for the pairing gap show a modest suppression with respect to the mean-field BCS values. These results can be connected to cold atom experiments, via the unitarity regime where fermionic superfluidity assumes a unified description, and they are important in the prediction of thermal properties and the cooling of neutron stars.
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Lu BN, Li N, Elhatisari S, Lee D, Drut JE, Lähde TA, Epelbaum E, Meißner UG. Ab Initio Nuclear Thermodynamics. PHYSICAL REVIEW LETTERS 2020; 125:192502. [PMID: 33216564 DOI: 10.1103/physrevlett.125.192502] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 08/06/2020] [Accepted: 09/29/2020] [Indexed: 05/28/2023]
Abstract
We propose a new Monte Carlo method called the pinhole trace algorithm for ab initio calculations of the thermodynamics of nuclear systems. For typical simulations of interest, the computational speedup relative to conventional grand-canonical ensemble calculations can be as large as a factor of one thousand. Using a leading-order effective interaction that reproduces the properties of many atomic nuclei and neutron matter to a few percent accuracy, we determine the location of the critical point and the liquid-vapor coexistence line for symmetric nuclear matter with equal numbers of protons and neutrons. We also present the first ab initio study of the density and temperature dependence of nuclear clustering.
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Affiliation(s)
- Bing-Nan Lu
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Ning Li
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Serdar Elhatisari
- Faculty of Engineering, Karamanoglu Mehmetbey University, Karaman 70100, Turkey
| | - Dean Lee
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA
| | - Joaquín E Drut
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599-3255, USA
| | - Timo A Lähde
- Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Evgeny Epelbaum
- Ruhr-Universität Bochum, Fakultät für Physik und Astronomie, Institut für Theoretische Physik II, D-44780 Bochum, Germany
| | - Ulf-G Meißner
- Institute for Advanced Simulation, Institut für Kernphysik, and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn, Germany
- Tbilisi State University, 0186 Tbilisi, Georgia
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Jensen S, Gilbreth CN, Alhassid Y. Contact in the Unitary Fermi Gas across the Superfluid Phase Transition. PHYSICAL REVIEW LETTERS 2020; 125:043402. [PMID: 32794813 DOI: 10.1103/physrevlett.125.043402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
A quantity known as the contact is a fundamental thermodynamic property of quantum many-body systems with short-range interactions. Determination of the temperature dependence of the contact for the unitary Fermi gas of infinite scattering length has been a major challenge, with different calculations yielding qualitatively different results. Here we use finite-temperature auxiliary-field quantum Monte Carlo (AFMC) methods on the lattice within the canonical ensemble to calculate the temperature dependence of the contact for the homogeneous spin-balanced unitary Fermi gas. We extrapolate to the continuum limit for 40, 66, and 114 particles, eliminating systematic errors due to finite-range effects. We observe a dramatic decrease in the contact as the superfluid critical temperature is approached from below, followed by a gradual weak decrease as the temperature increases in the normal phase. Our theoretical results are in excellent agreement with the most recent precision ultracold atomic gas experiments. We also present results for the energy as a function of temperature in the continuum limit.
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Affiliation(s)
- S Jensen
- Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520, USA
| | - C N Gilbreth
- Department of Physics, Central Washington University, Ellensburg, Washington 98926, USA
| | - Y Alhassid
- Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520, USA
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Dawkins WG, Carlson J, van Kolck U, Gezerlis A. Clustering of Four-Component Unitary Fermions. PHYSICAL REVIEW LETTERS 2020; 124:143402. [PMID: 32338952 DOI: 10.1103/physrevlett.124.143402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/13/2020] [Indexed: 06/11/2023]
Abstract
Ab initio nuclear physics tackles the problem of strongly interacting four-component fermions. The same setting could foreseeably be probed experimentally in ultracold atomic systems, where two- and three-component experiments have led to major breakthroughs in recent years. Both due to the problem's inherent interest and as a pathway to nuclear physics, in this Letter we study four-component fermions at unitarity via the use of quantum Monte Carlo methods. We explore novel forms of the trial wave function and find one which leads to a ground state of the eight-particle system whose energy is almost equal to that of two four-particle systems. We investigate the clustering properties involved and also extrapolate to the zero-range limit. In addition to being experimentally testable, our results impact the prospects of developing nuclear physics as a perturbation around the unitary limit.
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Affiliation(s)
- William G Dawkins
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - J Carlson
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - U van Kolck
- Institut de Physique Nucléaire, CNRS-IN2P3, Université Paris-Sud, Université Paris-Saclay, 91406 Orsay, France
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
| | - Alexandros Gezerlis
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Hoinka S, Lingham M, Fenech K, Hu H, Vale CJ, Drut JE, Gandolfi S. Precise determination of the structure factor and contact in a unitary Fermi gas. PHYSICAL REVIEW LETTERS 2013; 110:055305. [PMID: 23414031 DOI: 10.1103/physrevlett.110.055305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 12/09/2012] [Indexed: 06/01/2023]
Abstract
We present a high-precision determination of the universal contact parameter in a strongly interacting Fermi gas. In a trapped gas at unitarity, we find the contact to be 3.06±0.08 at a temperature of 0.08 of the Fermi temperature in a harmonic trap. The contact governs the high-momentum (short-range) properties of these systems, and this low-temperature measurement provides a new benchmark for the zero-temperature homogeneous contact. The experimental measurement utilizes Bragg spectroscopy to obtain the dynamic and static structure factors of ultracold Fermi gases at high momentum in the unitarity and molecular Bose-Einstein condensate regimes. We have also performed quantum Monte Carlo calculations of the static properties, extending from the weakly coupled BCS regime to the strongly coupled Bose-Einstein condensate case, that show agreement with experiment at the level of a few percent.
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Affiliation(s)
- Sascha Hoinka
- Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, Melbourne, Victoria 3122, Australia
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Bakr W, Cheuk L, Ku MH, Park J, Sommer A, Will S, Wu CH, Yefsah T, Zwierlein M. Strongly interacting Fermi gases. EPJ WEB OF CONFERENCES 2013. [DOI: 10.1051/epjconf/20135701002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Blume D. Few-body physics with ultracold atomic and molecular systems in traps. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2012; 75:046401. [PMID: 22790507 DOI: 10.1088/0034-4885/75/4/046401] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Few-body physics has played a prominent role in atomic, molecular and nuclear physics since the early days of quantum mechanics. It is now possible-thanks to tremendous progress in cooling, trapping and manipulating ultracold samples-to experimentally study few-body phenomena in trapped atomic and molecular systems with unprecedented control. This review summarizes recent studies of few-body phenomena in trapped atomic and molecular gases, with an emphasis on small trapped systems. We start by introducing the free-space scattering properties and then investigate what happens when two particles, bosons or fermions, are placed in an external confinement. Next, various three-body systems are treated analytically in limiting cases. Our current understanding of larger two-component Fermi systems and Bose systems is reviewed, and connections with the corresponding bulk systems are established. Lastly, future prospects and challenges are discussed. Throughout this review, commonalities with other systems such as nuclei or quantum dots are highlighted.
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Affiliation(s)
- D Blume
- Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814, USA
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Ku MJH, Sommer AT, Cheuk LW, Zwierlein MW. Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas. Science 2012; 335:563-7. [DOI: 10.1126/science.1214987] [Citation(s) in RCA: 498] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Mark J. H. Ku
- Department of Physics, Massachusetts Institute of Technology (MIT), MIT Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA
| | - Ariel T. Sommer
- Department of Physics, Massachusetts Institute of Technology (MIT), MIT Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA
| | - Lawrence W. Cheuk
- Department of Physics, Massachusetts Institute of Technology (MIT), MIT Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA
| | - Martin W. Zwierlein
- Department of Physics, Massachusetts Institute of Technology (MIT), MIT Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA
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The BCS–BEC Crossover and the Unitary Fermi Gas. THE BCS-BEC CROSSOVER AND THE UNITARY FERMI GAS 2012. [DOI: 10.1007/978-3-642-21978-8_1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Tan S. Universal energy functional for trapped Fermi gases with short range interactions. PHYSICAL REVIEW LETTERS 2011; 107:145302. [PMID: 22107206 DOI: 10.1103/physrevlett.107.145302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Indexed: 05/31/2023]
Abstract
Alhassid conjectured that the total energy of a harmonically trapped two-component Fermi gas with a short range interaction is a linear functional of the occupation probabilities of single-particle energy eigenstates. We confirm his conjecture and derive the functional explicitly. We show that the functional applies to all smooth (namely, differentiable) potentials having a minimum, not just harmonic traps. We also calculate the occupation probabilities of high energy states.
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Affiliation(s)
- Shina Tan
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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