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Autti S, Haley RP, Jennings A, Pickett GR, Poole M, Schanen R, Soldatov AA, Tsepelin V, Vonka J, Zavjalov VV, Zmeev DE. Transport of bound quasiparticle states in a two-dimensional boundary superfluid. Nat Commun 2023; 14:6819. [PMID: 37919295 PMCID: PMC10622538 DOI: 10.1038/s41467-023-42520-y] [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: 03/17/2023] [Accepted: 10/13/2023] [Indexed: 11/04/2023] Open
Abstract
The B phase of superfluid 3He can be cooled into the pure superfluid regime, where the thermal quasiparticle density is negligible. The bulk superfluid is surrounded by a quantum well at the boundaries of the container, confining a sea of quasiparticles with energies below that of those in the bulk. We can create a non-equilibrium distribution of these states within the quantum well and observe the dynamics of their motion indirectly. Here we show that the induced quasiparticle currents flow diffusively in the two-dimensional system. Combining this with a direct measurement of energy conservation, we conclude that the bulk superfluid 3He is effectively surrounded by an independent two-dimensional superfluid, which is isolated from the bulk superfluid but which readily interacts with mechanical probes. Our work shows that this two-dimensional quantum condensate and the dynamics of the surface bound states are experimentally accessible, opening the possibility of engineering two-dimensional quantum condensates of arbitrary topology.
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Affiliation(s)
- Samuli Autti
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
| | - Richard P Haley
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Asher Jennings
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
- RIKEN Center for Quantum Computing, RIKEN, Wako, 351-0198, Japan
| | - George R Pickett
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Malcolm Poole
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Roch Schanen
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Arkady A Soldatov
- P.L. Kapitza Institute for Physical Problems of RAS, 119334, Moscow, Russia
| | - Viktor Tsepelin
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - Jakub Vonka
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
- Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
| | | | - Dmitry E Zmeev
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
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Abstract
A time crystal is a macroscopic quantum system in periodic motion in its ground state. In our experiments, two coupled time crystals consisting of spin-wave quasiparticles (magnons) form a macroscopic two-level system. The two levels evolve in time as determined intrinsically by a nonlinear feedback, allowing us to construct spontaneous two-level dynamics. In the course of a level crossing, magnons move from the ground level to the excited level driven by the Landau-Zener effect, combined with Rabi population oscillations. We demonstrate that magnon time crystals allow access to every aspect and detail of quantum-coherent interactions in a single run of the experiment. Our work opens an outlook for the detection of surface-bound Majorana fermions in the underlying superfluid system, and invites technological exploitation of coherent magnon phenomena – potentially even at room temperature. Recent work has reported a realization of a time crystal in the form of the Bose-Einstein condensate of magnons in superfluid 3He. Here, the authors study the dynamics of a pair of such quantum time crystals and show that it closely resembles the evolution of a two-level system, modified by nonlinear feedback.
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3
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Autti S, Ahlstrom SL, Haley RP, Jennings A, Pickett GR, Poole M, Schanen R, Soldatov AA, Tsepelin V, Vonka J, Wilcox T, Woods AJ, Zmeev DE. Fundamental dissipation due to bound fermions in the zero-temperature limit. Nat Commun 2020; 11:4742. [PMID: 32958764 PMCID: PMC7506006 DOI: 10.1038/s41467-020-18499-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 08/26/2020] [Indexed: 11/12/2022] Open
Abstract
The ground state of a fermionic condensate is well protected against perturbations in the presence of an isotropic gap. Regions of gap suppression, surfaces and vortex cores which host Andreev-bound states, seemingly lift that strict protection. Here we show that in superfluid 3He the role of bound states is more subtle: when a macroscopic object moves in the superfluid at velocities exceeding the Landau critical velocity, little to no bulk pair breaking takes place, while the damping observed originates from the bound states covering the moving object. We identify two separate timescales that govern the bound state dynamics, one of them much longer than theoretically anticipated, and show that the bound states do not interact with bulk excitations.
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Affiliation(s)
- S Autti
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK.
| | - S L Ahlstrom
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - R P Haley
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - A Jennings
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - G R Pickett
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - M Poole
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - R Schanen
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - A A Soldatov
- P.L. Kapitza Institute for Physical Problems of RAS, Moscow, 119334, Russia
| | - V Tsepelin
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - J Vonka
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
- Paul Scherrer Institute, Forschungsstrasse 111, 5232, Villigen PSI, Switzerland
| | - T Wilcox
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
| | - A J Woods
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
- Department of Physics and NHMFL High B/T Facility, University of Florida, Gainesville, FL, 32611, USA
| | - D E Zmeev
- Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
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4
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Shook AJ, Vadakkumbatt V, Senarath Yapa P, Doolin C, Boyack R, Kim PH, Popowich GG, Souris F, Christani H, Maciejko J, Davis JP. Stabilized Pair Density Wave via Nanoscale Confinement of Superfluid ^{3}He. PHYSICAL REVIEW LETTERS 2020; 124:015301. [PMID: 31976679 DOI: 10.1103/physrevlett.124.015301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Indexed: 06/10/2023]
Abstract
Superfluid ^{3}He under nanoscale confinement has generated significant interest due to the rich spectrum of phases with complex order parameters that may be stabilized. Experiments have uncovered a variety of interesting phenomena, but a complete picture of superfluid ^{3}He under confinement has remained elusive. Here, we present phase diagrams of superfluid ^{3}He under varying degrees of uniaxial confinement, over a wide range of pressures, which elucidate the progressive stability of both the A phase, as well as a growing region of stable pair density wave state.
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Affiliation(s)
- A J Shook
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - V Vadakkumbatt
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - P Senarath Yapa
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - C Doolin
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - R Boyack
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - P H Kim
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - G G Popowich
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - F Souris
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - H Christani
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J Maciejko
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
- Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J P Davis
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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5
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Vorontsov AB. Andreev bound states in superconducting films and confined superfluid 3He. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2015.0144. [PMID: 29941623 PMCID: PMC6030148 DOI: 10.1098/rsta.2015.0144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
This paper reviews confinement-driven phase transitions in superconductors and Bardeen-Cooper-Schrieffer superfluids, and the appearance in thin films of new phases that break the time-reversal or translational symmetry. The origins of the new phases are closely tied to the Andreev scattering processes involving particle-hole conversions that create surface quasiparticle states with energies inside the superconducting gap. Restructuring of the low-energy spectrum in the surface region of several coherence lengths ξ0 results in large spatial variations of the superconducting order parameter. In confined geometry, such as slabs, films, pores or nano-dots, with one or more physical dimensions D∼10ξ0, the Andreev bound states can dominate properties of a superconductor, leading to modified experimental signatures. They can significantly change the energy landscape, and drive transitions into new superconducting phases. The new phases are expected in a variety of materials, from singlet d-wave superconductors to multi-component triplet superfluid 3He, but properties of the new phases will depend on the symmetry of the parent state. I will highlight the connection between the Andreev surface states and confinement-stabilized phases with additional broken symmetries, describe recent progress and open questions in the theoretical and experimental investigation of superfluids in confined geometry.This article is part of the theme issue 'Andreev bound states'.
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Affiliation(s)
- Anton B Vorontsov
- Department of Physics, Montana State University, Bozeman, MT 59717, USA
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Zhelev N, Abhilash TS, Bennett RG, Smith EN, Ilic B, Parpia JM, Levitin LV, Rojas X, Casey A, Saunders J. Fabrication of microfluidic cavities using Si-to-glass anodic bonding. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:073902. [PMID: 30068088 DOI: 10.1063/1.5031837] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We demonstrate the fabrication of ∼1.08 μm deep microfluidic cavities with characteristic size as large as 7 mm × 11 mm or 11 mm diameter, using a silicon-glass anodic bonding technique that does not require posts to act as separators to define cavity height. Since the phase diagram of 3He is significantly altered under confinement, posts might act as pinning centers for phase boundaries. The previous generation of cavities relied on full wafer-bonding which is more prone to failure and requires dicing post-bonding, whereas these cavities are made by bonding a pre-cut piece of Hoya SD-2 glass to a patterned piece of silicon in which the cavity is defined by etching. Anodic bonding was carried out at 425 °C with 200 V, and we observe that pressurizing the cavity to failure (>30 bars pressure) results in glass breaking, rather than the glass-silicon bond separation. In this article, we discuss the detailed fabrication of the cavity, its edges, and details of the junction between the coin silver fill line and the silicon base of the cavity that enables a low internal-friction joint. This feature is important for mass coupling torsional oscillator experimental assays of the superfluid inertial contribution where a high quality factor (Q) improves frequency resolution. The surface preparation that yields well-characterized smooth surfaces to eliminate pinning sites, the use of transparent glass as a cover permitting optical access, low temperature capability, and attachment of pressure-capable ports for fluid access may be features that are important in other applications.
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Affiliation(s)
- N Zhelev
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - T S Abhilash
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - R G Bennett
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - E N Smith
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - B Ilic
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - J M Parpia
- Department of Physics, Cornell University, Ithaca, New York 14853, USA
| | - L V Levitin
- Department of Physics, Royal Holloway University of London, Egham TW20 0EX, Surrey, United Kingdom
| | - X Rojas
- Department of Physics, Royal Holloway University of London, Egham TW20 0EX, Surrey, United Kingdom
| | - A Casey
- Department of Physics, Royal Holloway University of London, Egham TW20 0EX, Surrey, United Kingdom
| | - J Saunders
- Department of Physics, Royal Holloway University of London, Egham TW20 0EX, Surrey, United Kingdom
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The A-B transition in superfluid helium-3 under confinement in a thin slab geometry. Nat Commun 2017; 8:15963. [PMID: 28671184 PMCID: PMC5500879 DOI: 10.1038/ncomms15963] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 05/16/2017] [Indexed: 11/09/2022] Open
Abstract
The influence of confinement on the phases of superfluid helium-3 is studied using the torsional pendulum method. We focus on the transition between the A and B phases, where the A phase is stabilized by confinement and a spatially modulated stripe phase is predicted at the A–B phase boundary. Here we discuss results from superfluid helium-3 contained in a single 1.08-μm-thick nanofluidic cavity incorporated into a high-precision torsion pendulum, and map the phase diagram between 0.1 and 5.6 bar. We observe only small supercooling of the A phase, in comparison to bulk or when confined in aerogel, with evidence for a non-monotonic pressure dependence. This suggests that an intrinsic B-phase nucleation mechanism operates under confinement. Both the phase diagram and the relative superfluid fraction of the A and B phases, show that strong coupling is present at all pressures, with implications for the stability of the stripe phase. Superfluid helium-3 provides a clean testing ground for the understanding of quantum phases and their transitions. Here the authors show that when helium is confined in a nanofluidic cavity supercooling across the first-order A–B transition is suppressed, indicating an intrinsic nucleation mechanism.
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Zheng P, Jiang WG, Barquist CS, Lee Y, Chan HB. Critical Velocity in the Presence of Surface Bound States in Superfluid ^{3}He-B. PHYSICAL REVIEW LETTERS 2017; 118:065301. [PMID: 28234542 DOI: 10.1103/physrevlett.118.065301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Indexed: 06/06/2023]
Abstract
A microelectromechanical oscillator with a gap of 1.25 μm was immersed in superfluid ^{3}He-B and cooled below 250 μK at various pressures. Mechanical resonances of its shear motion were measured at various levels of driving force. The oscillator enters into a nonlinear regime above a certain threshold velocity. The damping increases rapidly in the nonlinear region and eventually prevents the velocity of the oscillator from increasing beyond the critical velocity which is much lower than the Landau critical velocity. We propose that this peculiar nonlinear behavior stems from the escape of quasiparticles from the surface bound states into the bulk fluid.
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Affiliation(s)
- P Zheng
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - W G Jiang
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - C S Barquist
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - Y Lee
- Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA
| | - H B Chan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
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