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Barresi A, Boulet A, Wlazłowski G, Magierski P. Generation and decay of Higgs mode in a strongly interacting Fermi gas. Sci Rep 2023; 13:11285. [PMID: 37438452 DOI: 10.1038/s41598-023-38176-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/04/2023] [Indexed: 07/14/2023] Open
Abstract
We investigate the life cycle of the large amplitude Higgs mode in strongly interacting superfluid Fermi gas. Through numerical simulations with time-dependent density functional theory and the technique of the interaction quench, we verify the previous theoretical predictions on the mode's frequency. Next, we demonstrate that the mode is dynamically unstable against external perturbation and qualitatively examine the emerging state after the mode decays. The post-decay state is characterized by spatial fluctuations of the order parameter and density at scales comparable to the superfluid coherence length scale. We identify similarities with FFLO states, which become more prominent at higher dimensionalities and nonzero spin imbalances.
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Affiliation(s)
- Andrea Barresi
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662, Warsaw, Poland
| | - Antoine Boulet
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662, Warsaw, Poland
- ISMANS CESI, 44 Avenue Frédéric Auguste Bartholdi, 72000, Le Mans, France
| | - 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.
| | - Piotr Magierski
- 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
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Wlazłowski G, Xhani K, Tylutki M, Proukakis NP, Magierski P. Dissipation Mechanisms in Fermionic Josephson Junction. PHYSICAL REVIEW LETTERS 2023; 130:023003. [PMID: 36706420 DOI: 10.1103/physrevlett.130.023003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/10/2022] [Accepted: 12/12/2022] [Indexed: 06/18/2023]
Abstract
We characterize numerically the dominant dynamical regimes in a superfluid ultracold fermionic Josephson junction. Beyond the coherent Josephson plasma regime, we discuss the onset and physical mechanism of dissipation due to the superflow exceeding a characteristic speed, and provide clear evidence distinguishing its physical mechanism across the weakly and strongly interacting limits, despite qualitative dynamics of global characteristics being only weakly sensitive to the operating dissipative mechanism. Specifically, dissipation in the strongly interacting regime occurs through the phase-slippage process, caused by the emission and propagation of quantum vortices, and sound waves-similar to the Bose-Einstein condensation limit. Instead, in the weak interaction limit, the main dissipative channel arises through the pair-breaking mechanism.
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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, Washington 98195-1560, USA
| | - Klejdja Xhani
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO), 50019 Sesto Fiorentino, Italy
| | - Marek Tylutki
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
| | - Nikolaos P Proukakis
- Joint Quantum Centre (JQC) Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Piotr Magierski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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Chen HZ, Liu XP, Wang XQ, Wu YP, Wang YX, Yao XC, Chen YA, Pan JW. 30 W, sub-kHz frequency-locked laser at 532 nm. OPTICS EXPRESS 2018; 26:33756-33763. [PMID: 30650808 DOI: 10.1364/oe.26.033756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/01/2018] [Indexed: 06/09/2023]
Abstract
We report on the realization of a high-power, ultranarrow-linewidth, and frequency-locked 532 nm laser system. The laser system consists of single-pass and intra-cavity second harmonic generation of a continuous-wave Ytterbium doped fiber laser at 1064 nm in the nonlinear crystal of periodically poled lithium niobate and lithium triborate, respectively. With 47 W infrared input, 30 W green laser is generated through the type I critical phase matching in the intracavity lithium triborate crystal. The laser linewidth is measured to be on the order of sub-kHz, which is achieved by simultaneously locking the single-pass frequency doubling output onto the iodine absorption line R69 (36-1) at 532 nm. Furthermore, the phase locking between the laser system and another slave 1064 nm laser is demonstrated with relative frequency tunability being up to 10 GHz. Our results completely satisfy the requirements of 532 nm laser for quantum simulation with ultracold atoms.
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Wlazłowski G, Sekizawa K, Marchwiany M, Magierski P. Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas. PHYSICAL REVIEW LETTERS 2018; 120:253002. [PMID: 29979062 DOI: 10.1103/physrevlett.120.253002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Indexed: 06/08/2023]
Abstract
Cold atoms experiments offer invaluable information on superfluid dynamics, including decay cascades of topological defects. While the cascade properties are well established for Bose systems, our understanding of their behavior in Fermi counterparts is very limited, in particular in spin-imbalanced systems, where superfluid (paired) and normal (unpaired) particles naturally coexist giving rise to complex spatial structure of the atomic cloud. Here we show, based on a newly developed microscopic approach, that the decay cascades of topological defects are dramatically modified by the spin polarization. We demonstrate that decay cascades end up at different stages: "dark soliton," "vortex ring," or "vortex line," depending on the polarization. We reveal that it is caused by sucking of unpaired particles into the soliton's internal structure. As a consequence vortex reconnections are hindered and we anticipate that quantum turbulence phenomenon can be significantly affected, indicating new physics induced by polarization effects.
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Affiliation(s)
- Gabriel Wlazłowski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Kazuyuki Sekizawa
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Maciej Marchwiany
- Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw, A. Pawińskiego 5a, Warsaw 02-106, Poland
| | - Piotr Magierski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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Kinnunen JJ, Baarsma JE, Martikainen JP, Törmä P. The Fulde-Ferrell-Larkin-Ovchinnikov state for ultracold fermions in lattice and harmonic potentials: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:046401. [PMID: 29293087 DOI: 10.1088/1361-6633/aaa4ad] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We review the concepts and the present state of theoretical studies of spin-imbalanced superfluidity, in particular the elusive Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, in the context of ultracold quantum gases. The comprehensive presentation of the theoretical basis for the FFLO state that we provide is useful also for research on the interplay between magnetism and superconductivity in other physical systems. We focus on settings that have been predicted to be favourable for the FFLO state, such as optical lattices in various dimensions and spin-orbit coupled systems. These are also the most likely systems for near-future experimental observation of the FFLO state. Theoretical bounds, such as Bloch's and Luttinger's theorems, and experimentally important limitations, such as finite-size effects and trapping potentials, are considered. In addition, we provide a comprehensive review of the various ideas presented for the observation of the FFLO state. We conclude our review with an analysis of the open questions related to the FFLO state, such as its stability, superfluid density, collective modes and extending the FFLO superfluid concept to new types of lattice systems.
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Affiliation(s)
- Jami J Kinnunen
- COMP Center of Excellence, Department of Applied Physics, Aalto University, Fi-00076, Aalto, Finland
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Loheac AC, Braun J, Drut JE. Equation of state of non-relativistic matter from automated perturbation theory and complex Langevin. EPJ WEB OF CONFERENCES 2018. [DOI: 10.1051/epjconf/201817503007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We calculate the pressure and density of polarized non-relativistic systems of two-component fermions coupled via a contact interaction at finite temperature. For the unpolarized one-dimensional system with an attractive interaction, we perform a thirdorder lattice perturbation theory calculation and assess its convergence by comparing with hybrid Monte Carlo. In that regime, we also demonstrate agreement with real Langevin. For the repulsive unpolarized one-dimensional system, where there is a so-called complex phase problem, we present lattice perturbation theory as well as complex Langevin calculations. For our studies, we employ a Hubbard-Stratonovich transformation to decouple the interaction and automate the application of Wick’s theorem for perturbative calculations, which generates the diagrammatic expansion at any order. We find excellent agreement between the results from our perturbative calculations and stochastic studies in the weakly interacting regime. In addition, we show predictions for the strong coupling regime as well as for the polarized one-dimensional system. Finally, we show a first estimate for the equation of state in three dimensions where we focus on the polarized unitary Fermi gas.
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Li JR, Lee J, Huang W, Burchesky S, Shteynas B, Top FÇ, Jamison AO, Ketterle W. A stripe phase with supersolid properties in spin–orbit-coupled Bose–Einstein condensates. Nature 2017; 543:91-94. [DOI: 10.1038/nature21431] [Citation(s) in RCA: 304] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/14/2017] [Indexed: 11/09/2022]
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Wlazłowski G, Sekizawa K, Magierski P, Bulgac A, Forbes MM. Vortex Pinning and Dynamics in the Neutron Star Crust. PHYSICAL REVIEW LETTERS 2016; 117:232701. [PMID: 27982659 DOI: 10.1103/physrevlett.117.232701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Indexed: 06/06/2023]
Abstract
The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force per unit length of the vortex line as a function of the vortex element to the nucleus separation.
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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, Washington 98195-1560, USA
| | - Kazuyuki Sekizawa
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, POLAND
| | - Piotr Magierski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, 00-662 Warsaw, POLAND
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Aurel Bulgac
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Michael McNeil Forbes
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
- Department of Physics and Astronomy, Washington State University, Pullman, Washington 98164-2814, USA
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Bulgac A, Magierski P, Roche KJ, Stetcu I. Induced Fission of (240)Pu within a Real-Time Microscopic Framework. PHYSICAL REVIEW LETTERS 2016; 116:122504. [PMID: 27058076 DOI: 10.1103/physrevlett.116.122504] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Indexed: 06/05/2023]
Abstract
We describe the fissioning dynamics of ^{240}Pu from a configuration in the proximity of the outer fission barrier to full scission and the formation of the fragments within an implementation of density functional theory extended to superfluid systems and real-time dynamics. The fission fragments emerge with properties similar to those determined experimentally, while the fission dynamics appears to be quite complex, with many excited shape and pairing modes. The evolution is found to be much slower than previously expected, and the ultimate role of the collective inertia is found to be negligible in this fully nonadiabatic treatment of nuclear dynamics, where all collective degrees of freedom (CDOF) are included (unlike adiabatic treatments with a small number of CDOF).
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Affiliation(s)
- Aurel Bulgac
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Piotr Magierski
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
- Faculty of Physics, Warsaw University of Technology, ulica Koszykowa 75, 00-662 Warsaw, Poland
| | - Kenneth J Roche
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Ionel Stetcu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Braun J, Finkbeiner S, Karbstein F, Roscher D. Search for inhomogeneous phases in fermionic models. Int J Clin Exp Med 2015. [DOI: 10.1103/physrevd.91.116006] [Citation(s) in RCA: 7] [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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Yefsah T, Sommer AT, Ku MJH, Cheuk LW, Ji W, Bakr WS, Zwierlein MW. Heavy solitons in a fermionic superfluid. Nature 2013; 499:426-30. [DOI: 10.1038/nature12338] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 05/28/2013] [Indexed: 11/09/2022]
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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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Forbes MM, Gandolfi S, Gezerlis A. Resonantly interacting fermions in a box. PHYSICAL REVIEW LETTERS 2011; 106:235303. [PMID: 21770516 DOI: 10.1103/physrevlett.106.235303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 04/06/2011] [Indexed: 05/31/2023]
Abstract
We use two fundamental theoretical frameworks to study the finite-size (shell) properties of the unitary gas in a periodic box: (1) an ab initio quantum Monte Carlo (QMC) calculation for boxes containing 4 to 130 particles provides a precise and complete characterization of the finite-size behavior, and (2) a new density functional theory (DFT) fully encapsulates these effects. The DFT predicts vanishing shell structure for systems comprising more than 50 particles, and allows us to extrapolate the QMC results to the thermodynamic limit, providing the tightest bound to date on the ground-state energy of the unitary gas: ξ(S)≤0.383(1). We also apply the new functional to few-particle harmonically trapped systems, comparing with previous calculations.
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Affiliation(s)
- Michael McNeil Forbes
- Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195-1560, USA
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Spin-imbalance in a one-dimensional Fermi gas. Nature 2010; 467:567-9. [DOI: 10.1038/nature09393] [Citation(s) in RCA: 428] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 08/03/2010] [Indexed: 11/08/2022]
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Gubbels KB, Baarsma JE, Stoof HTC. Lifshitz point in the phase diagram of resonantly interacting 6Li-40K mixtures. PHYSICAL REVIEW LETTERS 2009; 103:195301. [PMID: 20365934 DOI: 10.1103/physrevlett.103.195301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 10/16/2009] [Indexed: 05/29/2023]
Abstract
We consider a strongly interacting 6Li-40K mixture, which is imbalanced both in the masses and the densities of the two fermionic species. At present, it is the experimentalist's favorite for reaching the superfluid regime. We construct an effective thermodynamic potential that leads to excellent agreement with Monte Carlo results for the normal state. We use it to determine the universal phase diagram of the mixture in the unitarity limit, where we find, in contrast to the mass-balanced case, the presence of a Lifshitz point. This point is characterized by the effective mass of the Cooper pairs becoming negative, which signals an instability towards a supersolid phase.
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Affiliation(s)
- K B Gubbels
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
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Gezerlis A, Gandolfi S, Schmidt KE, Carlson J. Heavy-light fermion mixtures at unitarity. PHYSICAL REVIEW LETTERS 2009; 103:060403. [PMID: 19792545 DOI: 10.1103/physrevlett.103.060403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 06/29/2009] [Indexed: 05/28/2023]
Abstract
We investigate fermion pairing in the unitary regime for a mass ratio corresponding to a ;{6}Li-;{40}K mixture using quantum Monte Carlo methods. The ground-state energy and the average light- and heavy-particle excitation spectrum for the unpolarized superfluid state are nearly independent of the mass ratio. In the majority light system, the polarized superfluid is close to the energy of a phase separated mixture of nearly fully polarized normal and unpolarized superfluid. For a majority of heavy particles, we find an energy minimum for a normal state with a ratio of approximately 3ratio1 heavy to light particles. A slight increase in attraction to k_{F}a approximately 2.5 yields a ground state energy of nearly zero for this ratio. A cold unpolarized system in a harmonic trap at unitarity should phase separate into three regions, with a shell of unpolarized superfluid in the middle.
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Affiliation(s)
- Alexandros Gezerlis
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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Bulgac A, Yoon S. Large amplitude dynamics of the pairing correlations in a unitary fermi gas. PHYSICAL REVIEW LETTERS 2009; 102:085302. [PMID: 19257749 DOI: 10.1103/physrevlett.102.085302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 01/23/2009] [Indexed: 05/27/2023]
Abstract
A unitary Fermi gas has a surprisingly rich spectrum of large amplitude modes of the pairing field alone, which defies a description within a formalism involving only a reduced set of degrees of freedom, such as quantum hydrodynamics or a Landau-Ginzburg-like description. These modes are very slow, with oscillation frequencies well below the pairing gap, which makes their damping through quasiparticle excitations quite ineffective. In atomic traps these modes couple naturally with the density oscillations, and the corresponding oscillations of the atomic cloud are an example of a new type of collective mode in superfluid Fermi systems. They have lower frequencies than the compressional collective hydrodynamic oscillations, have a nonspherical momentum distribution, and could be excited by a quick time variation of the scattering length.
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Affiliation(s)
- Aurel Bulgac
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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