1
|
Fabritius P, Mohan J, Talebi M, Wili S, Zwerger W, Huang MZ, Esslinger T. Irreversible entropy transport enhanced by fermionic superfluidity. NATURE PHYSICS 2024; 20:1091-1096. [PMID: 39036649 PMCID: PMC11254751 DOI: 10.1038/s41567-024-02483-3] [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: 09/22/2023] [Accepted: 03/20/2024] [Indexed: 07/23/2024]
Abstract
The nature of particle and entropy flow between two superfluids is often understood in terms of reversible flow carried by an entropy-free, macroscopic wavefunction. While this wavefunction is responsible for many intriguing properties of superfluids and superconductors, its interplay with excitations in non-equilibrium situations is less understood. Here we observe large concurrent flows of both particles and entropy through a ballistic channel connecting two strongly interacting fermionic superfluids. Both currents respond nonlinearly to chemical potential and temperature biases. We find that the entropy transported per particle is much larger than the prediction of superfluid hydrodynamics in the linear regime and largely independent of changes in the channel's geometry. By contrast, the timescales of advective and diffusive entropy transport vary significantly with the channel geometry. In our setting, superfluidity counterintuitively increases the speed of entropy transport. Moreover, we develop a phenomenological model describing the nonlinear dynamics within the framework of generalized gradient dynamics. Our approach for measuring entropy currents may help elucidate mechanisms of heat transfer in superfluids and superconducting devices.
Collapse
Affiliation(s)
- Philipp Fabritius
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| | - Jeffrey Mohan
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| | - Mohsen Talebi
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| | - Simon Wili
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| | - Wilhelm Zwerger
- Physik Department, Technische Universität München, Garching, Germany
| | - Meng-Zi Huang
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| | - Tilman Esslinger
- Institute for Quantum Electronics & Quantum Center, ETH Zurich, Zurich, Switzerland
| |
Collapse
|
2
|
Adhikari R, Faina B, Ney V, Vorhauer J, Sterrer A, Ney A, Bonanni A. Effect of Impurity Scattering on Percolation of Bosonic Islands and Superconductivity in Fe Implanted NbN Thin Films. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3105. [PMID: 36144891 PMCID: PMC9505447 DOI: 10.3390/nano12183105] [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: 07/14/2022] [Revised: 08/25/2022] [Accepted: 09/03/2022] [Indexed: 06/16/2023]
Abstract
A reentrant temperature dependence of the thermoresistivity ρxx(T) between an onset local superconducting ordering temperature Tloconset and a global superconducting transition at T=Tglooffset has been reported in disordered conventional 3-dimensional (3D) superconductors. The disorder of these superconductors is a result of either an extrinsic granularity due to grain boundaries, or of an intrinsic granularity ascribable to the electronic disorder originating from impurity dopants. Here, the effects of Fe doping on the electronic properties of sputtered NbN layers with a nominal thickness of 100 nm are studied by means of low-T/high-μ0H magnetotransport measurements. The doping of NbN is achieved via implantation of 35 keV Fe ions. In the as-grown NbN films, a local onset of superconductivity at Tloconset=15.72K is found, while the global superconducting ordering is achieved at Tglooffset=15.05K, with a normal state resistivity ρxx=22μΩ·cm. Moreover, upon Fe doping of NbN, ρxx=40μΩ·cm is estimated, while Tloconset and Tglooffset are measured to be 15.1 K and 13.5 K, respectively. In Fe:NbN, the intrinsic granularity leads to the emergence of a bosonic insulator state and the normal-metal-to-superconductor transition is accompanied by six different electronic phases characterized by a N-shaped T dependence of ρxx(T). The bosonic insulator state in a s-wave conventional superconductor doped with dilute magnetic impurities is predicted to represent a workbench for emergent phenomena, such as gapless superconductivity, triplet Cooper pairings and topological odd frequency superconductivity.
Collapse
Affiliation(s)
- Rajdeep Adhikari
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria
| | | | | | | | | | | | - Alberta Bonanni
- Institut für Halbleiter-und-Festkörperphysik, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria
| |
Collapse
|
3
|
Tan ZB, Laitinen A, Kirsanov NS, Galda A, Vinokur VM, Haque M, Savin A, Golubev DS, Lesovik GB, Hakonen PJ. Thermoelectric current in a graphene Cooper pair splitter. Nat Commun 2021; 12:138. [PMID: 33420055 PMCID: PMC7794233 DOI: 10.1038/s41467-020-20476-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 11/29/2020] [Indexed: 11/17/2022] Open
Abstract
Generation of electric voltage in a conductor by applying a temperature gradient is a fundamental phenomenon called the Seebeck effect. This effect and its inverse is widely exploited in diverse applications ranging from thermoelectric power generators to temperature sensing. Recently, a possibility of thermoelectricity arising from the interplay of the non-local Cooper pair splitting and the elastic co-tunneling in the hybrid normal metal-superconductor-normal metal structures was predicted. Here, we report the observation of the non-local Seebeck effect in a graphene-based Cooper pair splitting device comprising two quantum dots connected to an aluminum superconductor and present a theoretical description of this phenomenon. The observed non-local Seebeck effect offers an efficient tool for producing entangled electrons. Thermoelectricity due to the interplay of the nonlocal Cooper pair splitting and the elastic co-tunneling in normal metal-superconductor-normal metal structure is predicted. Here, the authors observe the non-local Seebeck effect in a graphene-based Cooper pair splitting device.
Collapse
Affiliation(s)
- Z B Tan
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.,Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - A Laitinen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - N S Kirsanov
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland.,Terra Quantum AG, St. Gallerstrasse 16A, 9400, Rorschach, Switzerland.,Moscow Institute of Physics and Technology, Institutskii Per. 9, Dolgoprudny, Moscow Distr., 141700, Russian Federation.,Consortium for Advanced Science and Engineering (CASE), University of Chicago, 5801 S Ellis Avenue, Chicago, IL, 60637, USA
| | - A Galda
- James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.,Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL, 60439, USA
| | - V M Vinokur
- Consortium for Advanced Science and Engineering (CASE), University of Chicago, 5801 S Ellis Avenue, Chicago, IL, 60637, USA.,Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL, 60439, USA
| | - M Haque
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - A Savin
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland
| | - D S Golubev
- QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland
| | - G B Lesovik
- Terra Quantum AG, St. Gallerstrasse 16A, 9400, Rorschach, Switzerland.,Moscow Institute of Physics and Technology, Institutskii Per. 9, Dolgoprudny, Moscow Distr., 141700, Russian Federation
| | - P J Hakonen
- Low Temperature Laboratory, Department of Applied Physics, Aalto University, Espoo, Finland. .,QTF Centre of Excellence, Department of Applied Physics, Aalto University, FI-00076, Aalto, Finland.
| |
Collapse
|
4
|
Hu J, Rigosi AF, Newell DB, Chen YP. Thermoelectric transport in coupled double layers with interlayer excitons and exciton condensation. PHYSICAL REVIEW. B 2020; 102:235304. [PMID: 34485786 PMCID: PMC8412176 DOI: 10.1103/physrevb.102.235304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Quantum Boltzmann formalism is employed to study the transport properties of strongly-coupled double layer systems that enable the formation of interlayer excitons and exciton condensation. The importance of exciton formation, dissociation, and condensation is highlighted in the context of thermoelectric power generation, and this mathematical inquiry provides an alternative methodology to calculate the thermoelectric efficiency given the conditions of exciton formation. The Onsager relation for the Coulomb drag resistivity is shown to be valid even when exciton condensation is present. In addition, it is found that the traditional thermoelectric figure of merit is no longer sufficient to predict the efficiency of thermoelectric power generation in the presented situations. This inquiry offers insights for designing double layer systems, including their interlayer interactions, with enhanced thermoelectric energy conversion efficiency.
Collapse
Affiliation(s)
- Jiuning Hu
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Albert F. Rigosi
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - David B. Newell
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Yong P. Chen
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| |
Collapse
|
5
|
Abstract
Recent work done on the time reversal symmetry (TRS) breaking superconductors is reviewed in this paper. The special attention is paid to Sr 2 RuO 4 believed to be spin triplet chiral p-wave superconductor which break TRS and is expected to posses non-trivial topological properties. The family of TRS breaking superconductors is growing relatively fast, with many of its newly discovered members being non-centrosymmetric. However not only Sr 2 RuO 4 but also many other superconductors which possess center of inversion also break TRS. The TRS is often identified by means of the muon spin relaxation ( μ SR) and the Kerr effect. Both methods effectively measure the appearance of the spontaneous bulk magnetic field below superconducting transition temperature. This compound provides an example of the material whose many band, multi-condensate modeling has enjoyed a number of successes, but the full understanding has not been achieved yet. We discuss in some details the properties of the material. Among them is the Kerr effect and by understanding has resulted in the discovery of the novel mechanism of the phenomenon. The mechanism is universal and thus applicable to all systems with multi-orbital character of states at the Fermi energy.
Collapse
|
6
|
Hari R, Baillet S, Barnes G, Burgess R, Forss N, Gross J, Hämäläinen M, Jensen O, Kakigi R, Mauguière F, Nakasato N, Puce A, Romani GL, Schnitzler A, Taulu S. IFCN-endorsed practical guidelines for clinical magnetoencephalography (MEG). Clin Neurophysiol 2018; 129:1720-1747. [PMID: 29724661 PMCID: PMC6045462 DOI: 10.1016/j.clinph.2018.03.042] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 03/18/2018] [Accepted: 03/24/2018] [Indexed: 12/22/2022]
Abstract
Magnetoencephalography (MEG) records weak magnetic fields outside the human head and thereby provides millisecond-accurate information about neuronal currents supporting human brain function. MEG and electroencephalography (EEG) are closely related complementary methods and should be interpreted together whenever possible. This manuscript covers the basic physical and physiological principles of MEG and discusses the main aspects of state-of-the-art MEG data analysis. We provide guidelines for best practices of patient preparation, stimulus presentation, MEG data collection and analysis, as well as for MEG interpretation in routine clinical examinations. In 2017, about 200 whole-scalp MEG devices were in operation worldwide, many of them located in clinical environments. Yet, the established clinical indications for MEG examinations remain few, mainly restricted to the diagnostics of epilepsy and to preoperative functional evaluation of neurosurgical patients. We are confident that the extensive ongoing basic MEG research indicates potential for the evaluation of neurological and psychiatric syndromes, developmental disorders, and the integrity of cortical brain networks after stroke. Basic and clinical research is, thus, paving way for new clinical applications to be identified by an increasing number of practitioners of MEG.
Collapse
Affiliation(s)
- Riitta Hari
- Department of Art, Aalto University, Helsinki, Finland.
| | - Sylvain Baillet
- McConnell Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Gareth Barnes
- Wellcome Centre for Human Neuroimaging, University College of London, London, UK
| | - Richard Burgess
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Nina Forss
- Clinical Neuroscience, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Joachim Gross
- Centre for Cognitive Neuroimaging, University of Glasgow, Glasgow, UK; Institute for Biomagnetism and Biosignalanalysis, University of Muenster, Germany
| | - Matti Hämäläinen
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Harvard Medical School, Boston, MA, USA; NatMEG, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Ole Jensen
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Ryusuke Kakigi
- Department of Integrative Physiology, National Institute of Physiological Sciences, Okazaki, Japan
| | - François Mauguière
- Department of Functional Neurology and Epileptology, Neurological Hospital & University of Lyon, Lyon, France
| | | | - Aina Puce
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Gian-Luca Romani
- Department of Neuroscience, Imaging and Clinical Sciences, Università degli Studi G. D'Annunzio, Chieti, Italy
| | - Alfons Schnitzler
- Institute of Clinical Neuroscience and Medical Psychology, and Department of Neurology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Samu Taulu
- Institute for Learning & Brain Sciences, University of Washington, Seattle, WA, USA; Department of Physics, University of Washington, Seattle, WA, USA
| |
Collapse
|
7
|
Boto E, Meyer SS, Shah V, Alem O, Knappe S, Kruger P, Fromhold TM, Lim M, Glover PM, Morris PG, Bowtell R, Barnes GR, Brookes MJ. A new generation of magnetoencephalography: Room temperature measurements using optically-pumped magnetometers. Neuroimage 2017; 149:404-414. [PMID: 28131890 PMCID: PMC5562927 DOI: 10.1016/j.neuroimage.2017.01.034] [Citation(s) in RCA: 153] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 01/11/2017] [Accepted: 01/15/2017] [Indexed: 11/29/2022] Open
Abstract
Advances in the field of quantum sensing mean that magnetic field sensors, operating at room temperature, are now able to achieve sensitivity similar to that of cryogenically cooled devices (SQUIDs). This means that room temperature magnetoencephalography (MEG), with a greatly increased flexibility of sensor placement can now be considered. Further, these new sensors can be placed directly on the scalp surface giving, theoretically, a large increase in the magnitude of the measured signal. Here, we present recordings made using a single optically-pumped magnetometer (OPM) in combination with a 3D-printed head-cast designed to accurately locate and orient the sensor relative to brain anatomy. Since our OPM is configured as a magnetometer it is highly sensitive to environmental interference. However, we show that this problem can be ameliorated via the use of simultaneous reference sensor recordings. Using median nerve stimulation, we show that the OPM can detect both evoked (phase-locked) and induced (non-phase-locked oscillatory) changes when placed over sensory cortex, with signals ~4 times larger than equivalent SQUID measurements. Using source modelling, we show that our system allows localisation of the evoked response to somatosensory cortex. Further, source-space modelling shows that, with 13 sequential OPM measurements, source-space signal-to-noise ratio (SNR) is comparable to that from a 271-channel SQUID system. Our results highlight the opportunity presented by OPMs to generate uncooled, potentially low-cost, high SNR MEG systems.
Collapse
Affiliation(s)
- Elena Boto
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Sofie S Meyer
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom
| | - Vishal Shah
- QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA
| | - Orang Alem
- QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA
| | - Svenja Knappe
- QuSpin Inc., 2011 Cherry Street, Unit 112, Louisville, CO 80027, USA
| | - Peter Kruger
- Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - T Mark Fromhold
- Midlands Ultracold Atom Research Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Mark Lim
- Chalk Studios Ltd., 14 Windsor Street, London N1 8QG, United Kingdom
| | - Paul M Glover
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Peter G Morris
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Richard Bowtell
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Gareth R Barnes
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, United Kingdom
| | - Matthew J Brookes
- Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
| |
Collapse
|
8
|
Kleeorin Y, Meir Y, Giazotto F, Dubi Y. Large Tunable Thermophase in Superconductor - Quantum Dot - Superconductor Josephson Junctions. Sci Rep 2016; 6:35116. [PMID: 27734919 PMCID: PMC5062082 DOI: 10.1038/srep35116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/22/2016] [Indexed: 11/09/2022] Open
Abstract
In spite of extended efforts, detecting thermoelectric effects in superconductors has proven to be a challenging task, due to the inherent superconducting particle-hole symmetry. Here we present a theoretical study of an experimentally attainable Superconductor - Quantum Dot - Superconductor (SC-QD-SC) Josephson Junction. Using Keldysh Green's functions we derive the exact thermo-phase and thermal response of the junction, and demonstrate that such a junction has highly tunable thermoelectric properties and a significant thermal response. The origin of these effects is the QD energy level placed between the SCs, which breaks particle-hole symmetry in a gradual manner, allowing, in the presence of a temperature gradient, for gate controlled appearance of a superconducting thermo-phase. This thermo-phase increases up to a maximal value of ±π/2 after which thermovoltage is expected to develop. Our calculations are performed in realistic parameter regimes, and we suggest an experimental setup which could be used to verify our predictions.
Collapse
Affiliation(s)
- Yaakov Kleeorin
- Department of Physics, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
| | - Yigal Meir
- Department of Physics, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
| | - Francesco Giazotto
- NEST Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa, Italy
| | - Yonatan Dubi
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
- Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva, 84105, Israel
| |
Collapse
|