International Nuclear Information System (INIS)
Pushkarov, D.I.
2008-08-01
An analysis of previous theories of superfluidity of quantum solids is presented in relation to the nonclassical rotational moment of inertia (NCRM) found first in Kim and Chan experiments. A theory of supersolidity is proposed based on the presence of an additional conservation law. It is shown that the additional entropy or mass fluxes depend on the quasiparticle dispersion relation and vanish in the effective mass approximation. This implies that at low temperatures when the parabolic part of the dispersion relation predominates the supersolid properties should be less expressed. (author)
Dislocation-induced superfluidity in a model supersolid
Energy Technology Data Exchange (ETDEWEB)
Goswami, Debajit [Universitaet des Saarlandes, Saarbruecken (Germany); Dasbiswas, Kinjal; Dorsey, Alan [University of Florida, Gainesville, FL (United States); Yoo, Chi-Deuk [University of Minnesota, Minneapolis, MN (United States)
2012-07-01
Motivated by recent experiments on the supersolid behavior of {sup 4}He, we study the effect of an edge dislocation in promoting superfluidity in a Bose crystal. Using Landau theory, we couple the elastic strain field of the dislocation to the superfluid density, and use a linear analysis to show that superfluidity nucleates on the dislocation before occurring in the bulk of the solid. Moving beyond the linear analysis, we develop a systematic perturbation theory in the weakly nonlinear regime, and use this method to integrate out transverse degrees of freedom and derive a one-dimensional Landau equation for the superfluid order parameter. We then extend our analysis to a network of dislocation lines, and derive an XY model for the dislocation network by integrating over fluctuations in the order parameter. Our results show that the ordering temperature for the network has a sensitive dependence on the dislocation density, consistent with numerous experiments that find a clear connection between the sample quality and the supersolid response.
Defects in novel superfluids: Supersolid helium and cold gases
Dasbiswas, Kinjal
We investigate the role played by various topological defects, especially crystal dislocations and superfluid vortices, in some novel superfluids - such as the putative supersolid phase in solid helium-4 (4He) and in dilute Bose-Einstein condensates (BEC) in traps. The first part of this work addresses recent experimental findings in solid helium, such as the period shift in resonant oscillators that has been interpreted to be a signature of superfluidity coexisting with crystalline order in solid helium. We use Landau's phenomenological theory for phase transitions to establish that crystal defects such as dislocation lines and grain boundaries can induce local superfluid order and show that a network of dislocation lines can give rise to bulk superfluid order within a crystal. Our findings are also relevant to other phase transitions in the presence of crystal defects. The second part concerns the stability and dynamics of a single vortex in a rotating trap of a Bose-Einstein condensate (BEC) and the possibility of the macroscopic quantum tunneling of such a vortex from a metastable minimum at the trap center. The complete dynamics of such a vortex is derived by integrating out the phonon modes from a hydrodynamic action, and estimates for the tunneling rate are obtained using a variety of semiclassical methods. This is analogous to the problem of tunneling of a charged particle through a potential barrier in the presence of a very high magnetic field, the Magnus force on the vortex being analogous to the Lorentz force on a charge. We conclude that the vortex action has a complicated nonlocal form and further, that the Magnus-dominated dynamics of the vortex tends to suppress tunneling.
Supersolids: Solids Having Finite Volume and Infinite Surfaces.
Love, William P.
1989-01-01
Supersolids furnish an ideal introduction to the calculus topic of infinite series, and are useful for combining that topic with integration. Five examples of supersolids are presented, four requiring only a few basic properties of infinite series and one requiring a number of integration principles as well as infinite series. (MNS)
Energy Technology Data Exchange (ETDEWEB)
Balibar, Sebastien; Caupin, Frederic [Laboratoire de Physique Statistique de l' Ecole Normale Superieure, associe au CNRS et aux Universites Paris 6 et 7, 24 rue Lhomond, 75005 Paris (France)], E-mail: balibar@lps.ens.fr
2008-04-30
A solid is called 'supersolid' if it exhibits superfluid properties. Supersolidity is a paradoxical phenomenon whose understanding has become a major challenge since 2004, when Kim and Chan first observed what could be mass superflow through solid helium 4. In this review, we describe how successive experiments indicated that what was observed in helium 4 was not intrinsic properties of the crystalline state as originally proposed 35 years before. Disorder coming from how the solid is grown (dislocations, grain boundaries and other interfaces, liquid or glassy regions, impurities...) was shown to play an essential role. However, one does not know yet which type of disorder is involved or by which mechanism it leads to the observed properties. Furthermore, all the experimental features probably cannot be explained by a common mechanism. Recent measurements of the shear modulus of helium 4 crystals could even be explained without the need of any superfluidity. In fact, many theoretical predictions need to be checked experimentally, so the whole issue is far from understood. Even some crucial experiments would need to be repeated more systematically. The present review of the experimental observations and theoretical scenarios raises a series of questions which call for answers. (topical review)
Rittner, Ann Sophie C; Reppy, John D
2006-10-20
We have confirmed the existence, as first reported by Kim and Chan, of a supersolid state in solid 4He at temperatures below 250 mK. We have employed a torsional oscillator cell with a square cross section to insure a locking of the solid to the oscillating cell. We find that the nonclassical rotational inertia signal is not a universal property of solid 4He but can be eliminated through an annealing of the solid helium sample. This result has important implications for our understanding of the supersolid state.
Superfluidity at The Surface of Solid Hydrogen
Ceperley, David
1997-03-01
Over the last few decades, there has been a search for new bose-condensed systems. One of the likely candidates is molecular para-hydrogen, a boson with half the mass of helium. However, the interaction between hydrogen molecules is about four times as strong as between helium atoms, leading to a higher density, solid ground state, in which the hydrogen molecules are localized. Path integral Monte Carlo simulations have been carried out to examine to what extent hydrogen could become delocalized and hence superfluid. Imaginary-time path integrals are an exact method for computing the properties of bosonic systems at finite temperature (Ceperley, D.M. , Rev. Mod. Phys. 67), 279 (1995).. The thermodynamics of a quantum system are mapped onto a classical problem of exchanging ``ring-polymers'' which can then be simulated on a computer. Bose statistics correspond to the possibility ``cross-linking'' of polymers. Macroscopic exchanges are equivalent to superfluidity. Molecular para-hydrogen clusters have been examined. Cluster with fewer than 20 molecules have a non-zero superfluid density (Sindzingre,P., Ceperley, D. M., and Klein, M. L., Phys. Rev. Letts. 67), 1871 (1991).. The top layer of a clean planar hydrogen surface remains liquid (Wagner, M. and Ceperley, D. M., J. Low Temp. Phys. 94), 147 (1994); 102, 275 (1996). down to 5.5K in agreement with experiment and has very large zero point motion at lower temperatures. Systems with an incomplete topmost layer are superfluid at 1K but incomplete layers are not thermodynamically stable. The activation energy for a vacancy in the top layer is about 24K. This is too large for Bose condensation of vacancies to occur. Vacancy motion is however responsible for relaxation of hydrogen surfaces. It is possible that in ``dirty'' hydrogen films, the tendency for solidification is suppressed, allowing the film to undergo a Kosterlitz-Thouless transition at low temperatures. Recent simulations(Gordillo, M. C. and Ceperley, D. M
Superfluid-Quasicrystal in a Bose-Einstein Condensate
Hou, Junpeng; Hu, Haiping; Sun, Kuei; Zhang, Chuanwei
2018-02-01
A quasicrystal is a class of ordered structures defying conventional classification of solid crystals and may carry classically forbidden (e.g., fivefold) rotational symmetries. In view of long-sought supersolids, a natural question is whether a superfluid can spontaneously form quasicrystalline order that is not possessed by the underlying Hamiltonian, forming "superfluid-quasicrystals." Here we show that a superfluid-quasicrystal stripe state with the minimal fivefold rotational symmetry can be realized as the ground state of a Bose-Einstein condensate within a practical experimental scheme. There exists a rich phase diagram consisting of various superfluid-quasicrystal, supersolid, and plane-wave phases. Our scheme can be generalized for generating other higher-order (e.g., sevenfold) quasicrystal states, and provides a platform for investigating such new exotic quantum matter.
Driven-Dissipative Supersolid in a Ring Cavity
Mivehvar, Farokh; Ostermann, Stefan; Piazza, Francesco; Ritsch, Helmut
2018-03-01
Supersolids are characterized by the counterintuitive coexistence of superfluid and crystalline order. Here we study a supersolid phase emerging in the steady state of a driven-dissipative system. We consider a transversely pumped Bose-Einstein condensate trapped along the axis of a ring cavity and coherently coupled to a pair of degenerate counterpropagating cavity modes. Above a threshold pump strength the interference of photons scattered into the two cavity modes results in an emergent superradiant lattice, which spontaneously breaks the continuous translational symmetry towards a periodic atomic pattern. The crystalline steady state inherits the superfluidity of the Bose-Einstein condensate, thus exhibiting genuine properties of a supersolid. A gapless collective Goldstone mode correspondingly appears in the superradiant phase, which can be nondestructively monitored via the relative phase of the two cavity modes on the cavity output. Despite cavity-photon losses the Goldstone mode remains undamped, indicating the robustness of the supersolid phase.
Microscopic and hydrodynamic theory of superfluidity in periodic solids
International Nuclear Information System (INIS)
Saslow, W.M.
1977-01-01
The microscopic theory of fourth sound and of the superfluid fraction for perfect one-component periodic solids has been derived. It is applicable to finite temperatures and is restricted to the case of well-defined excitations. One finds that the superfluid fraction is a tensor rho/sub s//sub b//sub β//rho 0 and that the fourth-sound velocity C 4 is a tensor (C 2 4 )/sub b//sub β/ = (partialrho 0 /partialμ 0 ) -1 rho/sub s//sub b//sub β/, where μ 0 and rho 0 are the spatially averaged values of the chemical potential (per unit mass) and of the number density. In addition, the exact nonlinearized hydrodynamics is derived, and for fourth sound is found to give agreement with the microscopic theory. Because the superfluid velocity for a periodic solid cannot be generated by a Galilean transformation, it is found that elastic waves are loaded by the average mass density of the system. This is in contrast to the result of Andreev and Lifshitz, which involves only the superfluid fraction. Therefore one cannot look to (hydrodynamic) elastic waves for an obvious signature of superfluidity. A study of the effect of a transducer indicates that fourth sound will be generated to a non-negligible extent only when the crystal is imperfect (i.e., it has vacancies, interstitials, or impurities). On the other hand, a heater might be an effective generator of fourth sound, provided that the mean free path for umklapp processes is sufficiently small. In the limit of zero crystallinity the theory shows that second sound, rather than fourth sound, occurs. Detection of superflow by rotation experiments is also considered. It is pointed out that, because the superfluid velocity is not Galilean, two-fluid counterflow does not occur. Hence, it appears that rapid angular acceleration or deceleration would be the best technique for bringing the superfluid into rotation
Search for fourth sound propagation in supersolid 4He
International Nuclear Information System (INIS)
Aoki, Y.; Kojima, H.; Lin, X.
2008-01-01
A systematic study is carried out to search for fourth sound propagation solid 4 He samples below 500 mK down to 40 mK between 25 and 56 bar using the techniques of heat pulse generator and titanium superconducting transition edge bolometer. If solid 4 He is endowed with superfluidity below 200 mK, as indicated by recent torsional oscillator experiments, theories predict fourth sound propagation in such a supersolid state. If found, fourth sound would provide convincing evidence for superfluidity and a new tool for studying the new phase. The search for a fourth sound-like mode is based on the response of the bolometers to heat pulses traveling through cylindrical samples of solids grown with different crystal qualities. Bolometers with increasing sensitivity are constructed. The heater generator amplitude is reduced to the sensitivity limit to search for any critical velocity effects. The fourth sound velocity is expected to vary as ∞ √ Ρ s /ρ. Searches for a signature in the bolometer response with such a characteristic temperature dependence are made. The measured response signal has not so far revealed any signature of a new propagating mode within a temperature excursion of 5 μK from the background signal shape. Possible reasons for this negative result are discussed. Prior to the fourth sound search, the temperature dependence of heat pulse propagation was studied as it transformed from 'second sound' in the normal solid 4 He to transverse ballistic phonon propagation. Our work extends the studies of [V. Narayanamurti and R. C. Dynes, Phys. Rev. B 12, 1731 (1975)] to higher pressures and to lower temperatures. The measured transverse ballistic phonon propagation velocity is found to remain constant (within the 0.3% scatter of the data) below 100 mK at all pressures and reveals no indication of an onset of supersolidity. The overall dynamic thermal response of solid to heat input is found to depend strongly on the sample preparation procedure
Hydrodynamics of spatially ordered superfluids
Energy Technology Data Exchange (ETDEWEB)
Stoof, H.T. [Institute for Theoretical Physics, University of Utrecht, Princetonplein 5, P.O. Box 80.006, 3508 TA Utrecht (The Netherlands); Mullen, K. [Department of Physics, University of Oklahoma, Norman, Oklahoma 73019-0225 (United States); Wallin, M. [Department of Theoretical Physics, Royal Institute of Technology, S-100 44 Stockholm (Sweden); Girvin, S.M. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)
1996-03-01
We derive the hydrodynamic equations for the supersolid and superhexatic phases of a neutral two-dimensional Bose fluid. We find, assuming that the normal part of the fluid is clamped to an underlying substrate, that both phases can sustain third-sound modes and that in the supersolid phase there are additional modes due to the superfluid motion of point defects (vacancies and interstitials). {copyright} {ital 1996 The American Physical Society.}
NMR study of the dynamics of 3He impurities in the proposed supersolid state of solid 4He.
Kim, S S; Huan, C; Yin, L; Xia, J; Candela, D; Sullivan, N S
2011-05-06
The dynamics of (3)He atoms in solid (4)He have been investigated by measuring the NMR relaxation times T(1) and T(2) in the region where a significant nonclassical rotational inertia fraction has been reported. For (3)He concentrations x(3)=16 and 24 ppm, changes are observed for both the spin-lattice relaxation time T(1) and the spin-spin relaxation time T(2) at the temperatures corresponding to the onset of the nonclassical rotational inertia fraction and, at lower temperatures, to the (3)He-(4)He phase separation. The magnitudes of T(1) and T(2) at temperatures above the phase separation agree roughly with existing theory based on the tunneling of (3)He impurities in the elastic strain field due to isotopic mismatch. However, a distinct peak in T(1) and a less well-resolved feature in T(2) are observed near the reported nonclassical rotational inertia fraction onset temperature, in contrast to the temperature-independent relaxation times predicted by the tunneling theory.
Supersolidity of lattice bosons immersed in strongly correlated Rydberg dressed atoms
Li, Yongqiang; Geißler, Andreas; Hofstetter, Walter; Li, Weibin
2018-02-01
Recent experiments have illustrated that long-range two-body interactions can be induced by laser coupling atoms to highly excited Rydberg states. Stimulated by this achievement, we study the supersolidity of lattice bosons in an experimentally relevant situation. In our setup, we consider two-component atoms on a square lattice, where one species is weakly dressed to an electronically high-lying (Rydberg) state, generating a tunable, soft-core shape long-range interaction. Interactions between atoms of the second species and between the two species are characterized by local inter- and intraspecies interactions. Using a dynamical mean-field calculation, we find that interspecies on-site interactions can stabilize a pronounced region of supersolid phases. This is characterized by two distinctive types of supersolids, where the bare species forms supersolid phases that are immersed in strongly correlated quantum phases, i.e., a crystalline solid or supersolid of the dressed atoms. We show that the interspecies interaction leads to a rotonlike instability in the bare species and therefore is crucially important to the supersolid formation. We provide a detailed calculation of the interaction potential to show how our results can be explored under current experimental conditions.
Superfluid--Solid Quantum Phase Transitions and Landau-Ginzburg-Wilson Paradigm
Kuklov, A. B.; Prokof'ev, N. V.
2005-03-01
We study superfluid (SF)--solid zero-temperature transitions in 2d lattice boson/spin models by Worm-Algorithm Monte Carlo simulations. The SF -- Valence Bond Solid (VBS) transition was recently argued to be generically of II order in violation of the Ginzburg-Landau- Wilson (GLW) paradigm [1]. We simulate the J-current model on lattices up to 64x64x64, and observe that SF- columnar VBS and SF-checkerboard solid transitions are typically weak I-order ones and in small systems they may be confused with the continuous or high-symmetry points [2]. Thus, in the simulated model, the SF-VBS transition proceeds in agreement with the GLW paradigm. We explain this by dominance of standard particle and hole excitations, as opposed to fractionalized (spinon) excitations [1]. We developed a technique based on tunneling events (instantons) in the insulating phase which reveals charges of the revelant long-wave modes. While in 1d systems spinons are clearly seen in tunneling events, in two spatial dimensions tunneling is solely controlled by particles and holes in our system. This work is supported by NSF grant ITR-405460001 and PSC-CUNY- 665560035. [1] T. Senthil, A. Vishwanath, L. Balents, S. Sachdev, and M.P.A. Fisher, Science 303, 1490 (2004); [2] A.B. Kuklov, N.V. Prokof'ev, B.V. Svistunov, condmat/0406061; PRL, to be published.
A compact copper nuclear demagnetization cryostat and a search for superfluidity in solid 4He
International Nuclear Information System (INIS)
Haar, P.G. van de.
1991-01-01
The subject of this thesis is the theoretical and experimental study of matter at low temperatures, and the development of techniques to reach and measure these temperatures. A copper nuclear demagnetization cryostat was developed in order to reach low temperatures. This system distinguishes itself from other cryostats by its compact construction. The lowest temperature recorded by a pulsed Pt-NMR thermometer was 115 μK. This system was used to search for superfluidity in solid 4 He. Due to the large zero-point motion of the atoms, 4He remains liquid down to zero temperature; a pressure of 25.3 bar is needed to force the atoms in a lattice. Even in solid state, the 4 He atoms remain very mobile, changing lattice sites at a frequency of approximately 10 7 Hz. It is possible that solid 4 He contains vacancies at zero temperature. These zero point vacancies are expected to behave like a gas of bosons, and should Bose-condense at some temperature. From experiments the upper limit to the vacancy concentration is set of 4·10-5. (author). 217 refs.; 46 figs.; 2 tabs
International Nuclear Information System (INIS)
Ramesh, S.
1985-01-01
This thesis constitutes the first precise, quantitative experimental study of layering transitions, two-dimensional critical temperatures, and their relation to surface roughening. The experiments used superfluid fourth sound to probe the liquid solid 4 He interface, by coupling with surface waves unique to this interface. An annular resonator with electric transducers was used to measure the fourth sound velocity c 4 in an exfoliated graphite (Grafoil) superleak. Measurements of the pressure dependence of the fourth sound resonance frequencies (and attenuation) from ∼6 bar to ∼26 bar were made along eight isotherms from 1.0 K to 1.7 K. Plots of fourth sound resonance frequency versus coverage clearly indicate layer-by-layer solid nucleation and epitaxal growth of hcp solid 4 He on the basal plane of graphite. Further analysis yielded solid adsorption isotherms and a kinetic growth coefficient for the 4 He crystal surface and also indicated the existence of a critical temperature region and also indicated the existence of a critical temperature region around 1.0-1.2 K (the region of a bulk roughening transition). The acoustical theory for the experimental system was worked out using a parallel waveguide model; Landau's thermohydrodynamic equations were reformulated by including the mass- and heat-exchange effects occurring in the system; the equations were solved to obtain expressions for the velocity of sound propagation and attenuation
Nonclassical rotational inertia of a supersolid.
Aftalion, Amandine; Blanc, Xavier; Jerrard, Robert L
2007-09-28
As proposed by Leggett [Phys. Rev. Lett. 25, 1543 (1970)10.1103/PhysRevLett.25.1543], the supersolidity of a crystal is characterized by the nonclassicalical Rotational Inertia (NCRI) property. Using a model of quantum crystal introduced by Josserand, Pomeau, and Rica [Phys. Rev. Lett. 72, 2426 (1994)10.1103/PhysRevLett.72.2426], we prove that NCRI occurs. This is done by analyzing the ground state of the aforementioned model, which is related to a sphere packing problem, and then deriving a theoretical formula for the moment of inertia. We infer a lower estimate for the NCRI fraction, which is a landmark of supersolidity.
Analysis of motion of solid hydrogen tracer particles in oscillating superfluid flows
Czech Academy of Sciences Publication Activity Database
Zemma, E.; Luzuriaga, J.; Babuin, Simone
2014-01-01
Roč. 568, Part 1 (2014), s. 1-5, č. článku 012029. ISSN 1742-6588 Institutional support: RVO:68378271 Keywords : quantum turbulence * liquide helium * visualization * He-4 Subject RIV: BM - Solid Matter Physics ; Magnetism http://iopscience.iop.org/article/10.1088/1742-6596/568/1/012029/meta
Ketterson, John B
This book reports on the latest developments in the field of Superfluidity. The phenomenon has had a tremendous impact on the fundamental sciences as well as a host of technologies. It began with the discovery of superconductivity in mercury in 1911, which was ultimately described theoretically by the theory of Bardeen Cooper and Schriever (BCS) in 1957. The analogous phenomena, superfluidity, was discovered in helium in 1938 and tentatively explained shortly thereafter as arising from a Bose-Einstein Condensation (BEC) by London. But the importance of superfluidity, and the range of systems in which it occurs, has grown enormously. In addition to metals and the helium liquids the phenomena has now been observed for photons in cavities, excitons in semiconductors, magnons in certain materials, and cold gasses trapped in high vacuum. It very likely exist for neutrons in a neutron star and, possibly, in a conjectured quark state at their center. Even the Universe itself can be regarded as being in a kind of sup...
Baker, C A; Green, K; Grinten, M G D; Iaydjiev, P S; Ivanov, S N; Pendlebury, J M; Shiers, D B; Tucker, M A H; Yoshiki, H; Geltenbort, P
2003-01-01
As part of an R and D programme for the development of a next-generation experiment to measure the neutron electric dipole moment, in which ultra-cold neutrons (UCN) are produced and stored in superfluid sup 4 He (superthermal source), we have developed cryogenic detectors of UCN that can operate in situ within the superfluid. Surface barrier detectors and PIN diode detectors have been tested and proven to work well at temperatures as low as 80 mK. When combined with a layer of sup 6 LiF which converts neutrons to charged particles, these detectors form a reliable UCN detection system which has been tested in liquid helium down to 430 mK. The detectors have operated within superfluid helium for periods of up to 30 days with no signs of degradation. The development of this detection system has enabled us to measure the flux of UCN from a superthermal UCN source with no intervening transmission windows which can attenuate the flux. The addition of thin films of magnetically aligned iron also enables these detec...
Electric response in superfluid helium
Czech Academy of Sciences Publication Activity Database
Chagovets, Tymofiy
2016-01-01
Roč. 488, May (2016), s. 62-66 ISSN 0921-4526 R&D Projects: GA ČR GP13-03806P Institutional support: RVO:68378271 Keywords : superfluid helium * electric response * second sound * ions in He II Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2016
Hydrodynamics of spatially ordered superfluids
Stoof, H.T.C.; Mullen, K.; Wallin, M.; Girvin, S.M.
1996-01-01
We derive the hydrodynamic equations for the supersolid and superhexatic phases of a neutral two-dimensional Bose fluid. We find, assuming that the normal part of the fluid is clamped to an underlying substrate, that both phases can sustain third-sound modes and that in the supersolid phase there
Nonclassical rotational inertia for a supersolid under rotation
Aftalion, Amandine; Blanc, Xavier; Jerrard, Robert L.
2007-01-01
As proposed by Leggett [4], the supersolidity of a crystal is characterized by the Non Classical Rotational Inertia (NCRI) property. Using a model of quantum crystal introduced by Josserand, Pomeau and Rica [5], we prove that NCRI occurs. This is done by analyzing the ground state of the aforementioned model, which is related to a sphere packing problem, and then deriving a theoretical formula for the inertia momentum. We infer a lower estimate for the NCRI fraction, which is a landmark of su...
Hexatically ordered superfluids
Mullen, K.; Stoof, H.T.C.; Wallin, M.; Girvin, S.M.
1994-01-01
We develop a theory for a novel state of 4He films that possesses off-diagonal order (as in the superfluid state) as well as hexatic or bond orientational order. Within our description, both the hexatic and superfluid transitions are still on the Kosterlitz-Thouless type, but the superfluid
Instability of superfluid flow in the neutron star inner crust
Link, B.
2012-05-01
Pinning of superfluid vortices to the nuclear lattice of the inner crust of a neutron star supports a velocity difference between the superfluid and the solid as the star spins down. Under the Magnus force that arises on the vortex lattice, vortices undergo vortex creep through thermal activation or quantum tunnelling. We examine the hydrodynamic stability of this situation. Vortex creep introduces two low-frequency modes, one of which is unstable above a critical wavenumber for any non-zero flow velocity of the superfluid with respect to the solid. For typical pinning parameters of the inner crust, the superfluid flow is unstable over length scales ≲10 m and over time-scales as fast as months. The vortex lattice could degenerate into a tangle, and the superfluid flow could become turbulent. Unexpectedly large dissipation would suppress this instability.
Classification of a Supersolid: Trial Wavefunctions, Symmetry Breakings and Excitation Spectra
Chen, Yu; Ye, Jinwu; Tian, Guangshan
2012-11-01
A state of matter is characterized by its symmetry breaking and elementary excitations. A supersolid is a state which breaks both translational symmetry and internal U(1) symmetry. Here, we review some past and recent works in phenomenological Ginsburg-Landau theories, ground state trial wavefunctions and microscopic numerical calculations. We also write down a new effective supersolid Hamiltonian on a lattice. The eigenstates of the Hamiltonian contains both the ground state wavefunction and all the excited states (supersolidon) wavefunctions. We contrast various kinds of supersolids in both continuous systems and on lattices, both condensed matter and cold atom systems. We provide additional new insights in studying their order parameters, symmetry breaking patterns, the excitation spectra and detection methods.
Hydrodynamics of superfluid crystals
International Nuclear Information System (INIS)
Vardanyan, G.A.; Papoyan, K.V.; Sedrakyan, D.M.
1984-01-01
It is shown that three-velocity hydrodynamics equations describing the properties of a two-condensate crystal determine the low-frequency spectrum with allowance for superfluid drag. The drag on one superfluid component of density rho/sup( s/) 12 from another component of density rho/sup( s/) 22 , gives rise to two branches of vibrations of frequencies ω 1 and ω 2 , unlike the case of a one-condensate crystal. The absorption coefficient for transverse sound in a one-condensate crystal is expressed in terms of the quantum-mechanical characteristic quantity that describes the tunneling of atoms
Probable Observation of Quantized Vortex Lines Through Solid He Under DC Rotation
Yagi, Masahiko; Kitamura, Akira; Shimizu, Nobutaka; Yasuta, Yoshinori; Kubota, Minoru
2011-03-01
We report how one can detect quantized vortices in superfluids contained in cylindrical vessels in well-designed torsional oscillator (TO) experiments under DC rotation. We show the case of an artificial 3D superfluid (Fukuda et al. in Phys. Rev. B 71:212502, 2005) which is made of Kosterlits-Thouless 2D He film condensed on a porous glass substrate with a 3D connected surface of well-controlled pore size. We understand the TO experimental results with an extra energy dissipation peak under DC rotation by considering the circular quantized superflow around each of the vortex lines and interaction with thermally excited 2D vortices as discussed in Fukuda et al. (Phys. Rev. B 71:212502, 2005) and in Nemirovskii and Sonin (Phys. Rev. B 76: 224507, 2007). We discuss here the case of hcp solid 4He (see for ex. Balibar and Caupin in J. Phys., Condens. Matter 20:173201-1-19, 2008) and show the evidence of observation of the vortex lines penetration below a supersolid transition temperature (Kubota et al. in J. Low Temp. Phys. 158:572, 2010), T c , where macroscopic phase coherence is realized. It is found at exactly the same temperature T c , below which the hysteresis occurrs (Shimizu et ail. in arXiv:0903.1326, 2009). For hcp solid 4He we have reported the vortex fluid (VF) state onset temperature (Penzev et al. in Phys. Rev. Lett. 101:065301, 2008) T o =˜500 mK, by detailed drive velocity, V ac dependence study using TO technique. The TO response of the hcp 4He is characterized by the energy dissipation peaked at T p near 100 mK similar to the behavior in a KT transition. The real supersolid (SS) state occurs at T c below T p and much lower than T o . Our observation of the evidence of vortex lines penetration just below T c together with the VF state properties gives support for the idea that hcp 4He shares some features with the "new type of superconductors", where the vortex state, involving the VF as well as various vortex solid states, has been commonly discussed
Superfluid thermodynamic cycle refrigerator
Swift, Gregory W.; Kotsubo, Vincent Y.
1992-01-01
A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.
Modern trends in superconductivity and superfluidity
Kagan, M Yu
2013-01-01
This book concisely presents the latest trends in the physics of superconductivity and superfluidity and magnetism in novel systems, as well as the problem of BCS-BEC crossover in ultracold quantum gases and high-Tc superconductors. It further illuminates the intensive exchange of ideas between these closely related fields of condensed matter physics over the last 30 years of their dynamic development. The content is based on the author’s original findings obtained at the Kapitza Institute, as well as advanced lecture courses he held at the Moscow Engineering Physical Institute, Amsterdam University, Loughborough University and LPTMS Orsay between 1994 and 2011. In addition to the findings of his group, the author discusses the most recent concepts in these fields, obtained both in Russia and in the West. The book consists of 16 chapters which are divided into four parts. The first part describes recent developments in superfluid hydrodynamics of quantum fluids and solids, including the fashionable subject...
Energy Technology Data Exchange (ETDEWEB)
Roberts, David C [Los Alamos National Laboratory
2008-01-01
The article considers the dramatic phenomenon of seemingly frictionless flow of slow-moving superfluids. Specifically the question of whether an object in a superfluid flow experiences any drag force is addressed. A brief account is given of the history of this problem and it is argued that recent advances in ultracold atomic physics can shed much new light on this problem. The article presents the commonly held notion that sufficiently slow-moving superfluids can flow without drag and also discusses research suggesting that scattering quantum fluctuations might cause drag in a superfluid moving at any speed.
Fragmented-condensate solid of dipolar excitons
Andreev, S. V.
2017-05-01
We discuss a possible link between the recently observed macroscopic ordering of ultracold dipolar excitons (MOES) and the phenomenon of supersolidity. In the dilute limit we predict a stable supersolid state for a quasi-one-dimensional system of bosonic dipoles characterized by two- and three-body contact repulsion. We phenomenologically extend our theory to the strongly-correlated regime and find a critical value of the contact interaction parameter at which the supersolid exhibits a quantum phase transition to a fragmented state. The wavelength of the fragmented-condensate solid is defined by the balance between the quantum pressure and the entropy due to fluctuations of the relative phases between the fragments. Our model appears to be in good agreement with the relevant experimental data, including the very recent results on commensurability effect and wavelength of the MOES.
Hennigar, Robie A; Mann, Robert B; Tjoa, Erickson
2017-01-13
We present what we believe is the first example of a "λ-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid ^{4}He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically anti-de Sitter hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.
Vortices in superfluids. Les tourbillons dans les superfluides
Energy Technology Data Exchange (ETDEWEB)
Williams, G.
1991-12-01
Cooled near the absolute zero limits, liquid helium becomes superfluid. Since its discovery in 1937, this phenomenon has given rise to the interest of numerous Nobel prices, and today we know that superfluidity is a quantum property of matter, next to superconductivity, which allows some fluids to flow without apparent viscosity. However, a simple physical description was still missing of what's going on when heated superfluid helium is becoming a normal viscous liquid. Here, Gary Williams describes the scenario of this state change. Vortices, hydrodynamic remarkable structure, play the first role. Their importance, in supraconductivity, in magnetism or in cosmology should be greater than it was thought until now.
A Neutron Scattering Study of Collective Excitations in Superfluid Helium
DEFF Research Database (Denmark)
Graf, E. H.; Minkiewicz, V. J.; Bjerrum Møller, Hans
1974-01-01
Extensive inelastic-neutron-scattering experiments have been performed on superfluid helium over a wide range of energy and momentum transfers. A high-resolution study has been made of the pressure dependence of the single-excitation scattering at the first maximum of the dispersion curve over...... of the multiexcitation scattering was also studied. It is shown that the multiphonon spectrum of a simple Debye solid with the phonon dispersion and single-excitation cross section of superfluid helium qualitatively reproduces these data....
Superfluid helium tanker instrumentation
Energy Technology Data Exchange (ETDEWEB)
Woodhouse, C.E. (Johns Hopkins Univ., Baltimore, MD (USA). School of Medicine); Kashani, A. (Sterling Federal Systems, Inc., NASA/Ames Research Center, Moffett Field, CA (US)); Lukemire, A.T. (National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center)
1990-02-01
An instrumentation system for a 1992 space shuttle flight demonstration of a superfluid helium (SFHe) tanker and transfer technology is presented. This system provides measurement of helium temperatures, pressures, flow rates, mass, and the presence of liquid or vapor. The instrumentation system described consists of analog and digital portions which provide a space qualified electronics system that is fault tolerant, compact, and relatively lightweight. The data processing hardware and software are ground commandable, perform measurements asynchronously, and format telemetry for transmission to the ground. The novel heat pulse mass gaging technique is described. A new liquid/vapor sensor is presented. Flowmeters for SFHe are discussed. A SFHe fountain effect pump is described. Results of tests to date are presented.
Competition between the superfluidity and the slippage of 4He films adsorbed on porous gold
International Nuclear Information System (INIS)
Ideura, K; Kobayashi, H; Taniguchi, J; Suzuki, M; Hosomi, N
2009-01-01
We have carried out QCM measurements for 4 He films adsorbed on porous gold in the crossover region between the superfluidity and slippage. In relative low areal densities, the resonance frequency increases gradually below T S due to the slippage of solid film, while the superfluid onset is observed in high areal densities. In the crossover region, we observed a peculiar behavior: The increase in the resonance frequency below T S is suddenly suppressed at a certain temperature T D . From these observations, it is concluded that the superfluidity and the slippage of 4 He competes with each other.
Non Classical Rotational Inertia Fraction in a One Dimensional Model of Supersolid
Sepulveda, Néstor; Josserand, Christophe; Rica, Sergio
2011-01-01
We study the rotational inertia of a model of supersolid in the frame of the mean field Gross-Pitaevskii theory in one space dimension. We discuss the ground state of the model and the existence of a non classical inertia (NCRI) under rotation that models an annular geometry. An explicit formula for the NCRI is deduced. It depends on the density profil of the ground state, in full agreement with former theories. We compare the NCRI computed through this theory with direct numerical simulation...
On Kelvin-Helmholtz instability in superfluids
International Nuclear Information System (INIS)
Volovik, G.E.
2002-01-01
The problem of the Kelvin-Helmholtz (KH) instability in superfluids is discussed. The classical KH instability and the KH instability in superfluids at low temperature are considered. The results of experimental observations of such instabilities at the interface between superfluid 3 He-A and superfluid 3 He-B are analyzed. The causes of the disagreement of values for the instability threshold obtained by means of the Kelvin Helmholtz criterion and the modified Landau criterion are discussed [ru
Bifundamental superfluids from holography
Areán, Daniel; Tarrío, Javier
2015-04-01
We study the holographic dual of a (2 + 1)-dimensional s-wave superfluid that breaks an abelian U(1) × U(1) global symmetry group to the diagonal U(1) V . The model is inspired by Sen's tachyonic action, and the operator that condenses transforms in the bifundamental representation of the symmetry group. We focus on two configurations: the first one describes a marginal operator, and the phase diagram at finite temperature contains a first or a second order phase transition, depending on the parameters that determine the theory. In the second model the operator is relevant and the finite temperature transitions are always second order. In the latter case the conductivity for the current associated to the broken symmetry shows quasiparticle excitations at low temperatures, with mass given by the width of the superconducting gap. The suppression of spectral weight at low frequencies is also observed in the conductivity associated to the conserved symmetry, for which the DC value decreases as the temperature is reduced.
Bifundamental superfluids from holography
Energy Technology Data Exchange (ETDEWEB)
Areán, Daniel [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805, Munich (Germany); Tarrío, Javier [Departament de Física Fonamental andInstitut de Ciències del Cosmos, Universitat de Barcelona,Martí i Franquès 1, ES-08028, Barcelona (Spain)
2015-04-15
We study the holographic dual of a (2+1)-dimensional s-wave superfluid that breaks an abelian U(1)×U(1) global symmetry group to the diagonal U(1){sub V}. The model is inspired by Sen’s tachyonic action, and the operator that condenses transforms in the bifundamental representation of the symmetry group. We focus on two configurations: the first one describes a marginal operator, and the phase diagram at finite temperature contains a first or a second order phase transition, depending on the parameters that determine the theory. In the second model the operator is relevant and the finite temperature transitions are always second order. In the latter case the conductivity for the current associated to the broken symmetry shows quasiparticle excitations at low temperatures, with mass given by the width of the superconducting gap. The suppression of spectral weight at low frequencies is also observed in the conductivity associated to the conserved symmetry, for which the DC value decreases as the temperature is reduced.
Non-classical rotational inertia in the supersolid state
Koh, Shun-ichiro
2004-01-01
An abrupt drop in the moment of inertia recently found in solid helium 4 is explained in terms of dynamics of zero-point vacancies (ZPV). Mechanical decoupling of ZPV from the motion of the container due to Bose statistics is developed to a macroscopic phenomenon by repulsive interaction. It gives a negative answer to the question whether BEC is a necessary condition for non-classical rotational inertia in a bulk three-dimensional system.
Neutron scattering study of the excitation spectrum of solid helium at ...
Indian Academy of Sciences (India)
Abstract. There has been a resurgence of interest in the properties of solid helium due to the recent discovery of non-classical rotational inertia (NCRI) in solid 4He by Chan and coworkers below 200 mK which they have interpreted as a transition to a 'supersolid' phase. We have carried out a series of elastic and inelastic ...
Superconducting superfluids in neutron stars
International Nuclear Information System (INIS)
Carter, B.
2002-01-01
For treatment of the layers below the crust of a neutron star it is useful to employ a relativistic model involving three independently moving constituents, representing superfluid neutrons, superfluid protons, and degenerate negatively charged leptons. A Kalb-Ramond type formulation is used here to develop such a model for the specific purpose of application at the semi macroscopic level characterised by lengthscales that are long compared with the separation between the highly localised and densely packed proton vortices of the Abrikosov type lattice that carries the main part of the magnetic flux, but that are short compared with the separation between the neutron vortices. (orig.)
Collective excitations in unconventional superconductors and superfluids
Brusov, Peter
2009-01-01
This is the first monograph that strives to give a complete and detailed description of the collective modes (CMs) in unconventional superfluids and superconductors (UCSF&SC). Using the most powerful method of modern theoretical physics - the path (functional) integral technique - authors build the three- and two-dimensional models for s -, p - and d -wave pairing in neutral as well as in charged Fermi-systems, models of superfluid Bose-systems and Fermi-Bose-mixtures. Within these models they study the collective properties of such systems as superfluid 3 He, superfluid 4 He, superfluid 3 He-
Propagative modes along a superfluid helium-4 meniscus
International Nuclear Information System (INIS)
Poujade, M.; Guthmann, C.; Rolley, E.
2002-01-01
We have studied the dynamics of a superfluid helium-4 meniscus on a solid substrate. In a pseudo-non-wetting situation, there is no hysteresis of the contact angle. We show that distortions of a liquid meniscus do propagate along the contact line. We have analyzed the propagation of pulses. We find a good agreement with theoretical predictions by Brochard for the dispersion relation of oscillation modes of the contact line. (authors)
Boundary effects on sound propagation in superfluids
International Nuclear Information System (INIS)
Jensen, H.H.; Smith, H.; Woelfle, P.
1983-01-01
The attenuation of fourth sound propagating in a superfluid confined within a channel is determined on a microscopic basis, taking into account the scatter of the quasiparticles from the walls. The Q value of a fourth-sound resonance is shown to be inversely proportional to the stationary flow of thermal excitations through the channel due to an external force. Our theoretical estimates of Q are compared with experimentally observed values for 3 He. The transition between first and fourth sound is studied in detail on the basis of two-fluid hydrodynamics, including the slip of the normal component at the walls. The slip is shown to have a strong influence on the velocity and attenuation in the transition region between first and fourth sound, offering a means to examine the interaction of quasiparticles with a solid surface
Searching for Supersolidity in Ultracold Atomic Bose Condensates with Rashba Spin-Orbit Coupling
Liao, Renyuan
2018-04-01
We developed a functional integral formulation for the stripe phase of spinor Bose-Einstein condensates with Rashba spin-orbit coupling. The excitation spectrum is found to exhibit double gapless band structures, identified to be two Goldstone modes resulting from spontaneously broken internal gauge symmetry and translational invariance symmetry. The sound velocities display anisotropic behavior with the lower branch vanishing in the direction perpendicular to the stripe in the x -y plane. At the transition point between the plane-wave phase and the stripe phase, physical quantities such as fluctuation correction to the ground-state energy and quantum depletion of the condensates exhibit discontinuity, characteristic of the first-order phase transition. Despite strong quantum fluctuations induced by Rashba spin-orbit coupling, we show that the supersolid phase is stable against quantum depletion. Finally, we extend our formulation to finite temperatures to account for interactions between excitations.
Monitoring and manipulating Higgs and Goldstone modes in a supersolid quantum gas.
Léonard, Julian; Morales, Andrea; Zupancic, Philip; Donner, Tobias; Esslinger, Tilman
2017-12-15
Higgs and Goldstone modes are collective excitations of the amplitude and phase of an order parameter that is related to the breaking of a continuous symmetry. We directly studied these modes in a supersolid quantum gas created by coupling a Bose-Einstein condensate to two optical cavities, whose field amplitudes form the real and imaginary parts of a U(1)-symmetric order parameter. Monitoring the cavity fields in real time allowed us to observe the dynamics of the associated Higgs and Goldstone modes and revealed their amplitude and phase nature. We used a spectroscopic method to measure their frequencies, and we gave a tunable mass to the Goldstone mode by exploring the crossover between continuous and discrete symmetry. Our experiments link spectroscopic measurements to the theoretical concept of Higgs and Goldstone modes. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.
Novel sound phenomena in superfluid helium in aerogel and other impure superfluids
International Nuclear Information System (INIS)
Brusov, Peter; Brusov, Paul; Lawes, Gavin; Lee, Chong; Matsubara, Akira; Ishikawa, Osamu; Majumdar, Pinaki
2003-01-01
During the last decade new techniques for producing impure superfluids with unique properties have been developed. This new class of systems includes superfluid helium confined to aerogel, HeII with different impurities (D 2 , N 2 , Ne, Kr), superfluids in Vycor glasses, and watergel. These systems exhibit very unusual properties including unexpected acoustic features. We discuss the sound properties of these systems and show that sound phenomena in impure superfluids are modified from those in pure superfluids. We calculate the coupling between temperature and pressure oscillations for impure superfluids and for superfluid He in aerogel. We show that the coupling between these two sound modes is governed either by c∂ρ/∂c or σρ a ρ s (for aerogel) rather than thermal expansion coefficient ∂ρ/∂T, which is enormously small in pure superfluids. This replacement plays a fundamental role in all sound phenomena in impure superfluids. It enhances the coupling between the two sound modes that leads to the existence of such phenomena as the slow mode and heat pulse propagation with the velocity of first sound observed in superfluids in aerogel. This means that it is possible to observe in impure superfluids such unusual sound phenomena as slow pressure (density) waves and fast temperature (entropy) waves. The enhancement of the coupling between the two sound modes decreases the threshold values for nonlinear processes as compared to pure superfluids. Sound conversion, which has been observed in pure superfluids only by shock waves should be observed at moderate sound amplitude in impure superfluids. Cerenkov emission of second sound by first sound (which never been observed in pure superfluids) could be observed in impure superfluids
International Nuclear Information System (INIS)
Niyaz, P.
1993-01-01
Quantum Monte Carlo techniques were used to study two quantum many-body systems, the one-dimensional extended boson-Hubbard Hamiltonian, a model of superfluid-insulator quantum phase transitions, and the two-dimensional Holstein Model, a model for electron-phonon interactions. For the extended boson-Hubbard model, the authors studied the ground state properties at commensurate filling (density = 1) and half-integer filling (density = 1/2). At commensurate filling, the system has two possible insulating phases for strong coupling. If the on-site repulsion dominates, the system freezes into an insulating phase where each site is singly occupied. If the intersite repulsion dominates, doubly occupied and empty sites alternate. At weak coupling, the system becomes a superfluid. The authors investigated the order of phase transitions between these different phases. At half-integer filling, the authors found one strong coupling insulating phase, where singly occupied and empty sites alternate, and a weak coupling superfluid phase. The authors also investigated the possibility of a supersolid phase and found no clear evidence of such a new phase. For the electron-phonon (Holstein) model, the authors focused on the finite temperature phase transition from a metallic state to an insulating charge density wave (CDW) state as the temperature is lowered. The authors present the first calculation of the spectral density from Monte Carlo data for this system. The authors also investigated the formation of a CDW state as a function of various parameters characterizing the electron-phonon interactions. Using these numerical results as benchmarks, the authors then investigated different levels of Migdal approximations. The authors found the solutions of a set of gapped Migdal-Eliashberg equations agreed qualitatively with the Monte Carlo results
Intrinsic topological superfluidity - fluctuations and response
Levin, K.; Wu, Chien-Te; Anderson, Brandon; Boyack, Rufus
Recent interest in topological superconductivity is based primarily on exploiting proximity effects to obtain this important phase. However, in cold gases it is possible to contemplate ``intrinsic'' topological superfluidity produced with a synthetic spin-orbit coupling and Zeeman field. It is important for such future experiments to establish how low in temperature one needs to go to reach the ordered phase. Similarly, it will be helpful to have a probe of the normal (pseudogap) phase to determine if the ultimate superfluid order will be topological or trivial. In this talk, we address these issues by considering fluctuation effects in such a superfluid, and calculate the critical transition temperature and response functions. We see qualitative signatures of topological superfluidity in spin and charge response functions. We also explore the suppression of superfluidity due to fluctuations, and importantly find that the temperature scales necessary to reach topological superfluidity are reasonably accessible
Penetration of superfluid turbulence through porous filters
International Nuclear Information System (INIS)
Foreman, L.R.; Snyder, H.A.
1979-01-01
The equilibrium concentration of superfluid turbulence on two sides of small-pore filters is studied as a function of pore size. The filter forms a common wall between two second-sound resonance cavities. The attenuation of standing waves of second sound is used to detect the turbulence which is created in the superfluid with a rotating paddle. We find that superfluid turbulence does not pass through filters of 7.5 nm diameter, but penetrates filters with 50-nm pores
International Nuclear Information System (INIS)
Theodorakis, S.
1988-01-01
This paper presents a phenomenological Lagrangian that fully describes the dynamics of any homogeneous phase of superfluid 3 He, unitary or not, omitting relaxation. This Lagrangian is built by using the concept of a local SO(3) x SO(3) x U(1) symmetry. The spin and angular momentum play the role of gauge fields. We derive the Leggett equations for spin and orbital dynamics from the equations of motion, for both the A and the B phase. This Lagrangian not only enables us to describe both the spin and orbital dynamics of superfluid 3 He in a unified fashion, but can also be used for finding the dynamics in any experimental situation. Furthermore, it can describe the dynamics of the magnitude, as well as of the orientation of the order parameter, and thus it can be used to describe the dynamics of the A-B phase transition
Simplicity works for superfluid helium
Energy Technology Data Exchange (ETDEWEB)
Bowley, Roger [University of Nottingham, Nottingham (United Kingdom)
2000-02-01
The famous philosopher Karl Popper once said that ''science is the art of systematic oversimplification''. Indeed, when faced with a new puzzle the trick is to simplify it without losing the essential physics - something that is easier said than done. However, this approach has paid off recently in low-temperature physics. Last year Richard Packard, Seamus Davis and co-workers at the University of California at Berkeley encountered a puzzling new phenomenon in superfluid helium-3, a quantum fluid that remains a liquid close to absolute zero and exhibits unusual properties such as the ability to flow without friction (A Machenkov et al. 1999 Phys. Rev. Lett. 83 3860). Previous experiments had revealed that certain effects in liquid helium are analogous to effects observed in superconductors, materials that lose all resistance to electric current at low temperatures. When the Berkeley researchers connected two reservoirs of superfluid helium-3, the superfluid flowed back and forth through apertures that formed a ''weak link'' between the two containers. This behaviour is similar to the oscillatory current of electrons that can flow across an insulating gap separating two superconductors - a device that is known as a Josephson junction. What was puzzling about the Berkeley results was that the helium-3 had two different stable configurations, both of which behaved in an unconventional way compared with a Josephson junction. This puzzle has now been solved independently by Sidney Yip at the National Center for Theoretical Sciences in Taiwan, and by Janne Viljas and Erkki Thuneberg at the Helsinki University of Technology in Finland (Phys. Rev. Lett. 1999 83 3864 and 3868). In this article the author describes the latest research on superfluid helium. (UK)
Berkeley Experiments on Superfluid Macroscopic Quantum Effects
International Nuclear Information System (INIS)
Packard, Richard
2006-01-01
This paper provides a brief history of the evolution of the Berkeley experiments on macroscopic quantum effects in superfluid helium. The narrative follows the evolution of the experiments proceeding from the detection of single vortex lines to vortex photography to quantized circulation in 3He to Josephson effects and superfluid gyroscopes in both 4He and 3He
Radioactive ions and atoms in superfluid helium
Dendooven, P.G.; Purushothaman, S.; Gloos, K.; Aysto, J.; Takahashi, N.; Huang, W.; Harissopulos, S; Demetriou, P; Julin, R
2006-01-01
We are investigating the use of superfluid helium as a medium to handle and manipulate radioactive ions and atoms. Preliminary results on the extraction of positive ions from superfluid helium at temperatures close to 1 K are described. Increasing the electric field up to 1.2 kV/cm did not improve
Dark matter superfluidity and galactic dynamics
Directory of Open Access Journals (Sweden)
Lasha Berezhiani
2016-02-01
Full Text Available We propose a unified framework that reconciles the stunning success of MOND on galactic scales with the triumph of the ΛCDM model on cosmological scales. This is achieved through the physics of superfluidity. Dark matter consists of self-interacting axion-like particles that thermalize and condense to form a superfluid in galaxies, with ∼mK critical temperature. The superfluid phonons mediate a MOND acceleration on baryonic matter. Our framework naturally distinguishes between galaxies (where MOND is successful and galaxy clusters (where MOND is not: dark matter has a higher temperature in clusters, and hence is in a mixture of superfluid and normal phase. The rich and well-studied physics of superfluidity leads to a number of striking observational signatures.
Dynamics of quantised vortices in superfluids
Sonin, Edouard B
2016-01-01
A comprehensive overview of the basic principles of vortex dynamics in superfluids, this book addresses the problems of vortex dynamics in all three superfluids available in laboratories (4He, 3He, and BEC of cold atoms) alongside discussions of the elasticity of vortices, forces on vortices, and vortex mass. Beginning with a summary of classical hydrodynamics, the book guides the reader through examinations of vortex dynamics from large scales to the microscopic scale. Topics such as vortex arrays in rotating superfluids, bound states in vortex cores and interaction of vortices with quasiparticles are discussed. The final chapter of the book considers implications of vortex dynamics to superfluid turbulence using simple scaling and symmetry arguments. Written from a unified point of view that avoids complicated mathematical approaches, this text is ideal for students and researchers working with vortex dynamics in superfluids, superconductors, magnetically ordered materials, neutron stars and cosmological mo...
Path-integral computation of superfluid densities
International Nuclear Information System (INIS)
Pollock, E.L.; Ceperley, D.M.
1987-01-01
The normal and superfluid densities are defined by the response of a liquid to sample boundary motion. The free-energy change due to uniform boundary motion can be calculated by path-integral methods from the distribution of the winding number of the paths around a periodic cell. This provides a conceptually and computationally simple way of calculating the superfluid density for any Bose system. The linear-response formulation relates the superfluid density to the momentum-density correlation function, which has a short-ranged part related to the normal density and, in the case of a superfluid, a long-ranged part whose strength is proportional to the superfluid density. These facts are discussed in the context of path-integral computations and demonstrated for liquid 4 He along the saturated vapor-pressure curve. Below the experimental superfluid transition temperature the computed superfluid fractions agree with the experimental values to within the statistical uncertainties of a few percent in the computations. The computed transition is broadened by finite-sample-size effects
Hydrogen-bond memory and water-skin supersolidity resolving the Mpemba paradox.
Zhang, Xi; Huang, Yongli; Ma, Zengsheng; Zhou, Yichun; Zhou, Ji; Zheng, Weitao; Jiang, Qing; Sun, Chang Q
2014-11-14
The Mpemba paradox, that is, hotter water freezes faster than colder water, has baffled thinkers like Francis Bacon, René Descartes, and Aristotle since B.C. 350. However, a commonly accepted understanding or theoretical reproduction of this effect remains challenging. Numerical reproduction of observations, shown herewith, confirms that water skin supersolidity [Zhang et al., Phys. Chem. Chem. Phys., DOI: ] enhances the local thermal diffusivity favoring heat flowing outwardly in the liquid path. Analysis of experimental database reveals that the hydrogen bond (O:H-O) possesses memory to emit energy at a rate depending on its initial storage. Unlike other usual materials that lengthen and soften all bonds when they absorb thermal energy, water performs abnormally under heating to lengthen the O:H nonbond and shorten the H-O covalent bond through inter-oxygen Coulomb coupling [Sun et al., J. Phys. Chem. Lett., 2013, 4, 3238]. Cooling does the opposite to release energy, like releasing a coupled pair of bungees, at a rate of history dependence. Being sensitive to the source volume, skin radiation, and the drain temperature, the Mpemba effect proceeds only in the strictly non-adiabatic 'source-path-drain' cycling system for the heat "emission-conduction-dissipation" dynamics with a relaxation time that drops exponentially with the rise of the initial temperature of the liquid source.
Collective excitations and supersolid behavior of bosonic atoms inside two crossed optical cavities
Lang, J.; Piazza, F.; Zwerger, W.
2017-12-01
We discuss the nature of symmetry breaking and the associated collective excitations for a system of bosons coupled to the electromagnetic field of two optical cavities. For the specific configuration realized in a recent experiment at ETH [1, 2], we show that, in absence of direct intercavity scattering and for parameters chosen such that the atoms couple symmetrically to both cavities, the system possesses an approximate U(1) symmetry which holds asymptotically for vanishing cavity field intensity. It corresponds to the invariance with respect to redistributing the total intensity I={I}1+{I}2 between the two cavities. The spontaneous breaking of this symmetry gives rise to a broken continuous translation-invariance for the atoms, creating a supersolid-like order in the presence of a Bose-Einstein condensate. In particular, we show that atom-mediated scattering between the two cavities, which favors the state with equal light intensities {I}1={I}2 and reduces the symmetry to {{Z}}2\\otimes {{Z}}2, gives rise to a finite value ˜ \\sqrt{I} of the effective Goldstone mass. For strong atom driving, this low energy mode is clearly separated from an effective Higgs excitation associated with changes of the total intensity I. In addition, we compute the spectral distribution of the cavity light field and show that both the Higgs and Goldstone mode acquire a finite lifetime due to Landau damping at non-zero temperature.
Observation of non-classical rotational inertia in bulk solid 4He
Kondo, Motoshi; Takada, Shunichi; Shibayama, Yoshiyuki; Shirahama, Keiya
2006-01-01
In recent torsional oscillator experiments by Kim and Chan (KC), a decrease of rotational inertia has been observed in solid 4He in porous materials and in a bulk annular channel. This observation strongly suggests the existence of "non-classical rotational inertia" (NCRI), i.e. superflow, in solid 4He. In order to study such a possible "supersolid" phase, we perform torsional oscillator experiments for cylindrical solid 4He samples. We have observed decreases of rotational inertia below 200 ...
Fourth sound in relativistic superfluidity theory
International Nuclear Information System (INIS)
Vil'chinskij, S.I.; Fomin, P.I.
1995-01-01
The Lorentz-covariant equations describing propagation of the fourth sound in the relativistic theory of superfluidity are derived. The expressions for the velocity of the fourth sound are obtained. The character of oscillation in sound is determined
Superfluidity and Superconductivity in Neutron Stars
Indian Academy of Sciences (India)
Neutron stars, the compact stellar remnants of core-collapse supernova explosions, are unique cosmic laboratories for exploring novel phases of matter under extreme conditions. In particular, the occurrence of superfluidity and superconductivity in neutron stars will be briefly reviewed.
Effective theory of bosonic superfluids
International Nuclear Information System (INIS)
Schakel, A.M.J.
1994-01-01
The authors discuss the effective theory of a bosonic superfluid whose microscopic behavior is described by a nonrelativistic, weak-coupling φ 4 theory in the phase with broken particle number symmetry, both at zero temperature and in the vicinity of the phase transition. In the zero-temperature regime, the theory is governed by the gapless Goldstone mode resulting from the broken symmetry. Although this mode is gapless, the effective theory turns out to be Gallilei invariant. The regime just below the critical temperature is approached in a high-temperature expansion which is shown to be consistent with the weak-coupling assumption of the theory. The authors calculate the critical temperature, the coefficients of the Landau theory, and the finite-temperature sound velocity. A comparison with BCS theory is given
Two-dimensional superfluid transition in Hdown
International Nuclear Information System (INIS)
Mello, E.V.L.; Carneiro, G.M.
1984-11-01
The surface density as function of temperature for Hdown adsorbed on superfluid helium film is studied for several gas densities. The theory used is exact in the low density limit and predict Kosterlitz-thouless transition temperatures lower than previous calculation and also lower saturation density. The results confirm the possibility of a 2D superfluid transition under conditions close to those achieved experimentally. (Author) [pt
Neutron stars with outbursts from superfluid crust
Kaminker, A. D.; Chaikin, E. A.; Kaurov, A. A.; Yakovlev, D. G.
2017-12-01
We model heat propagation and the thermal surface luminosity L{s}^∞ ≤ft( t \\right) of a neutron star after an internal outburst in its crust. Simulations take into account superfluidity of free neutrons and the thickness of the outbursting layer (heater) in the crust. Crustal superfluidity can shorten and intensify variations of L{s}^∞ ≤ft( t \\right).
Superfluid helium three: some hydrodynamic measurements
International Nuclear Information System (INIS)
Lyden, J.K.
1979-01-01
An oscillating viscometer was designed to measure the superfluid fraction and normal fraction viscosity of 3 He in the A and B phases above two millikelvin. A basically parallel plate geometry, low flow velocities, and magnetic shielding were used to obtain the conditions necessary for measuring only one selected component of the superfluid fraction and normal fraction viscosity tensors in the A phase. The apparatus was successfully cooled through the superfluid transition at nine pressures from 10 bar to greater than 30 bar. Pendulum data were obtained in both the A and B phases, and the T/sub AB/ transition was observed at 23, 25, and 29 bar. However, the period and damping data in the superfluid phases displayed prominent resonance phenomena that make the data interpretation problematic. Superfluid fraction initial slope values (K) and values of the strong coupling parameter (S) were determined. The resonance pattern was repeatable on temperature cycling at 23 bar and displayed a similar pattern from pressure to pressure. A model of the resonances being due to second sound propagating between the cell plates displayed qualitatively correct pressure dependence of a particular mode's temperature location and approximately correct temperature spacings for the different modes at a particular pressure. Within the model, the distribution of plate spacings implied the correct relative temperature widths for the large resonances at the different pressures. If this model is correct, then this resonance phenomenon (present in both phases) would represent the first observation of second sound in superfluid 3 He
Directory of Open Access Journals (Sweden)
D. V. Kuis
2010-01-01
Full Text Available The mechanism of structure formation in super-solid carbon phase in nanocomposite on the basis of iron and nano-disperse carbon, which can be used at development of technology and composition of creation of new materials using inexpensive nano-carbon materials is offered.
Prediction of a Mobile Solid State in Dense Hydrogen under High Pressures
Geng, Hua Y.; Wu, Q.; Sun, Y.
2017-01-01
Solid rigidity and liquid-scale mobility are thought incompatible in elemental substances. One cannot have an elemental solid that is long-range positionally ordered wherein the atoms flow like in a liquid simultaneously. The only exception might be the hypothetical supersolid state of 4He. In this work, we demonstrate that such exotic state could exist even in the classical regime. Using ab initio molecular dynamics (AIMD) and ab initio path integral molecular dynamics (AI-PIMD), a novel sta...
Apparent de-wetting due to superfluid flow
Poujade, M; Rolley, E
2002-01-01
We have investigated the wetting behaviour of superfluid helium-4 on silicon. Surprisingly, we observe pseudo-de-wetting: though a thick superfluid film covers the substrate, the meniscus displays a finite contact angle which decreases from about 5 deg C at low temperature down to zero at the superfluid transition. We show that this behaviour can be explained by a pressure decrease due to a superfluid flow, closely related to the Kontorovich effect. (authors)
Magnon condensation and spin superfluidity
Bunkov, Yury M.; Safonov, Vladimir L.
2018-04-01
We consider the Bose-Einstein condensation (BEC) of quasi-equilibrium magnons which leads to spin superfluidity, the coherent quantum transfer of magnetization in magnetic material. The critical conditions for excited magnon density in ferro- and antiferromagnets, bulk and thin films, are estimated and discussed. It was demonstrated that only the highly populated region of the spectrum is responsible for the emergence of any BEC. This finding substantially simplifies the BEC theoretical analysis and is surely to be used for simulations. It is shown that the conditions of magnon BEC in the perpendicular magnetized YIG thin film is fulfillied at small angle, when signals are treated as excited spin waves. We also predict that the magnon BEC should occur in the antiferromagnetic hematite at room temperature at much lower excited magnon density compared to that of ferromagnetic YIG. Bogoliubov's theory of Bose-Einstein condensate is generalized to the case of multi-particle interactions. The six-magnon repulsive interaction may be responsible for the BEC stability in ferro- and antiferromagnets where the four-magnon interaction is attractive.
International Nuclear Information System (INIS)
Holm, D.D.; Kupershmidt, B.A.
1987-01-01
Four levels of nonlinear hydrodynamic description are presented for a nondissipative multicondensate solution of superfluids with vorticity. First, the multivelocity superfluid (MVSF) theory is extended to the case of a multivelocity superfluid plasma (MVSP), in which some of the superfluid condensates (protons, say) are charged and coupled electromagnetically to an additional, normal, charged fluid (electrons). The resulting drag-current density is derived due to the electromagnetic coupling of the condensates with the normal fluids. For the case of one charged condensate, the MVSP equations simplify to what we call superfluid Hall magnetohydrodynamics (SHMHD) in the approximation that displacement current and electron inertia are negligible, and local charge neutrality is imposed. The contribution of the charged condensate to the Hall drift force is determined. In turn, neglecting the Hall effect in SHMHD gives the equations of superfluid magnetohydrodynamics (SMHD). Each set of equations (MVSF, MVSP, SHMHD, and SMHD) is shown to be Hamiltonian and to possess a Poisson bracket associated with the dual space of a corresponding semidirect-product Lie algebra with a generalized two-cocycle defined on it. Topological conservation laws (helicities) associated with the kernels of these Lie algebras are also discussed as well as those associated physically with generalized Kelvin theorems for conservation of superfluid circulation around closed loops moving with the normal fluid
Holographic thermal relaxation in superfluid turbulence
Energy Technology Data Exchange (ETDEWEB)
Du, Yiqiang [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); Niu, Chao [Institute of High Energy Physics, Chinese Academy of Sciences,Beijing 100049 (China); Tian, Yu [School of Physics, University of Chinese Academy of Sciences,Beijing 100049 (China); State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Sciences,Beijing 100190 (China); Zhang, Hongbao [Department of Physics, Beijing Normal University,Beijing 100875 (China); Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes,Pleinlaan 2, B-1050 Brussels (Belgium)
2015-12-02
Holographic duality provides a first-principles approach to investigate real time processes in quantum many-body systems, in particular at finite temperature and far-from-equilibrium. We use this approach to study the dynamical evolution of vortex number in a two-dimensional (2D) turbulent superfluid through numerically solving its gravity dual. We find that the temporal evolution of the vortex number can be well fit statistically by two-body decay due to the vortex pair annihilation featured relaxation process, thus confirm the previous suspicion based on the experimental data for turbulent superfluid in highly oblate Bose-Einstein condensates. Furthermore, the decay rate near the critical temperature is in good agreement with the recently developed effective theory of 2D superfluid turbulence.
Wave processes in a superfluid liquid
International Nuclear Information System (INIS)
Sanikidze, D.G.
1981-01-01
The monograph is devoted to theory of sound wave propagation in superfluid He 4 and He 3 -He 4 solutions. Hydrodynamic theory of sound oscillation propagation in superfluid liquid under conditions of confined geometry is given. In particular considered are problems of propagation of the first, second and fourth sounds, dispersion, attenuation and absorption, sound propagation in films, channels and waveguides. The monograph summarizes a certain stage of studying different sound oscillations in superfluid liquid and along with original results contains also results obtained by other investigators. The theory and experimental investigations carried on both in the Soviet Union and abroad are compared. The monograph is intended for specialists working in the area of low temperature physics and for students of the given speciality [ru
Realization of mechanical rotation in superfluid helium
Gordon, E. B.; Kulish, M. I.; Karabulin, A. V.; Matyushenko, V. I.; Dyatlova, E. V.; Gordienko, A. S.; Stepanov, M. E.
2017-09-01
The possibility of using miniaturized low-power electric motors submerged in superfluid helium for organization of rotation inside a cryostat has been investigated. It has been revealed that many of commercial micromotors can operate in liquid helium consuming low power. Turret with 5 sample holders, assembled on the base of stepper motor, has been successfully tested in experiments on the nanowire production in quantized vortices of superfluid helium. Application of the stepper motor made it possible in a single experiment to study the effect of various experimental parameters on the yield and quality of the nanowires. The promises for continuous fast rotation of the bath filled by superfluid helium by using high-speed brushless micromotor were outlined and tested. Being realized, this approach will open new possibility to study the guest particles interaction with the array of parallel linear vortices in He II.
Indian Academy of Sciences (India)
particles out of which the solid is made. For bosons, they may form a condensate, giving rise to a superfluid coexisting with the solid. This supersolid phase is discussed in certain bosonic models [2]. ..... If one looks at the distribution of the angles θi of the local currents, one can see more precisely in figure 7 how the currents ...
Superfluid helium at subcritical active core
International Nuclear Information System (INIS)
Vasil'ev, V.V.; Lopatkin, A.V.; Muratov, V.G.; Rakhno, I.L.
2002-01-01
Power range and neutron flux wherein super thermal source was realized at high volume of superfluid helium were investigated. MCU, BRAND, MCNP codes were used for the calculation of reactors. It is shown that the availability of full-size diameter for cryogenic source of ultracold neutrons, as the source with superfluid helium is considered, is possible in the reflector of subcritical assembly. Results obtained from the MCNP-4B code application demonstrated that the density of thermal neutron flux in helium must be not higher than 2.3 x 10 11 s -1 cm -2 [ru
Superfluid helium-4: An introductory review
International Nuclear Information System (INIS)
Vinen, W.F.
1983-01-01
Helium was first liquefied by Kamerlingh Onnes in Leiden in July 1908, an achievement that followed much careful and painstaking work. On the same day Onnes reduced the temperature of his helium to a value approaching lK, and he must therefore have produced and observed the superfluid phase. These experimental discoveries led very quickly to a series of remarkable theoretical contributions that laid the foundations for all subsequent work. The period since the second world war has of course seen an enormous amount of work on superfluid helium-4. In reviewing it the author tries to see it in terms of two threads: one originating from Landau; the other from London
Majorana-Fermi-Segre, E.-L.; Antonoff-Overhauser-Salam, Marvin-Albert-Abdus; Siegel, Edward Carl-Ludwig
2013-03-01
Majorana-fermions, being their own antiparticles, following non-Abelian anyon/semion quantum-statistics: in Zhang et.al.-...-Detwiler et.al.-...``Worlds-in-Collision'': solid-state/condensed-matter - physics spin-orbit - coupled topological-excitations in superconductors and/or superfluids -to- particle-physics neutrinos: ``When `Worlds' Collide'', analysis via Siegel[Schrodinger Centenary Symp., Imperial College, London (1987); in The Copenhagen-Interpretation Fifty-Years After the Como-Lecture, Symp. Fdns. Mod.-Phys., Joensu(1987); Symp. on Fractals, MRS Fall-Mtg., Boston(1989)-5-papers!!!] ``complex quantum-statistics in fractal-dimensions'', which explains hidden-dark-matter(HDM) IN Siegel ``Sephirot'' scenario for The Creation, uses Takagi[Prog.Theo.Phys. Suppl.88,1(86)]-Ooguri[PR D33,357(85)] - Picard-Lefschetz-Arnol'd-Vassil'ev[``Principia Read After 300 Years'', Not.AMS(1989); quantum-theory caveats comment-letters(1990); Applied Picard-Lefschetz Theory, AMS(2006)] - theorem quantum-statistics, which via Euler- formula becomes which via de Moivre- -formula further becomes which on unit-circle is only real for only, i.e, for, versus complex with imaginary-damping denominator for, i.e, for, such that Fermi-Dirac quantum-statistics for
Convectively driven superfluid turbulence in dilute solutions of 3He in superfluid 4He
International Nuclear Information System (INIS)
Ecke, R.E.; Haucke, H.; Wheatley, J.
1986-10-01
A dilute solution of 3 He in superfluid 4 He usually behaves as a single component classical fluid in the context of hydrodynamic convection. However, certain convective states can be excited which do not seem to exist in classical convection. These states are characterized by noisy temperature fluctuations and a pronounced decrease in thermal conductance relative to the classical convecting states. Critical convective flow fields are observed analogous to critical velocities for superfluid turbulence in pipes. The magnitude of the average critical velocities for these two types of superfluid turbulence are in good agreement. Also, a quantitative estimate of energy dissipation due to the interaction of normal fluid and quantized vortex lines appears to account for the large decrease in thermal heat transport for the turbulent states. These states are identified as states of convectively driven superfluid turbulence. 23 refs., 5 figs
Spin Superfluidity and Magnone BEC in He-3
Bunkov, Yury
2011-03-01
The spin superfluidity -- superfluidity in the magnetic subsystem of a condensed matter -- is manifested as the spontaneous phase-coherent precession of spins first discovered in 1984 in 3 He-B. This superfluid current of spins -- spin supercurrent -- is one more representative of superfluid currents known or discussed in other systems, such as the superfluid current of mass and atoms in superfluid 4 He; superfluid current of electric charge in superconductors; superfluid current of hypercharge in Standard Model of particle physics; superfluid baryonic current and current of chiral charge in quark matter; etc. Spin superfluidity can be described in terms of the Bose condensation of spin waves -- magnons. We discuss different states of magnon superfluidity with different types of spin-orbit coupling: in bulk 3 He-B; magnetically traped `` Q -balls'' at very low temperatures; in 3 He-A and 3 He-B immerged in deformed aerogel; etc. Some effects in normal 3 He can also be treated as a magnetic BEC of fermi liquid. A very similar phenomena can be observed also in a magnetic systems with dinamical frequensy shift, like MnC03 . We will discuss the main experimental signatures of magnons superfluidity: (i) spin supercurrent, which transports the magnetization on a macroscopic distance more than 1 cm long; (ii) spin current Josephson effect which shows interference between two condensates; (iii) spin current vortex -- a topological defect which is an analog of a quantized vortex in superfluids, of an Abrikosov vortex in superconductors, and cosmic strings in relativistic theories; (iv) Goldstone modes related to the broken U (1) symmetry -- phonons in the spin-superfluid magnon gas; etc. For recent review see Yu. M. Bunkov and G. E. Volovik J. Phys. Cond. Matter. 22, 164210 (2010) This work is partly supported by the Ministry of Education and Science of the Russian Federation (contract N 02.740.11.5217).
Small objects in superfluid 3He
International Nuclear Information System (INIS)
Rainer, D.; Vuorio, M.
1977-02-01
Distortions in the superfluid order parameter around a small object in 3 He are calculated together with the supercurrents and the angular momentum induced by it in the liquid. The forces acting on the impurity by the liquid texture structure are also considered. (author)
Excitations in Topological Superfluids and Superconductors
Wu, Hao
In this thesis I present the theoretical work on Fermionic surface states, and %the bulk Bosonic collective excitations in topological superfluids and superconductors. Broken symmetries %Bulk-edge correspondence in topological condensed matter systems have implications for the spectrum of Fermionic excitations confined on surfaces or topological defects. (Abstract shortened by ProQuest.).
Sounds in one-dimensional superfluid helium
International Nuclear Information System (INIS)
Um, C.I.; Kahng, W.H.; Whang, E.H.; Hong, S.K.; Oh, H.G.; George, T.F.
1989-01-01
The temperature variations of first-, second-, and third-sound velocity and attenuation coefficients in one-dimensional superfluid helium are evaluated explicitly for very low temperatures and frequencies (ω/sub s/tau 2 , and the ratio of second sound to first sound becomes unity as the temperature decreases to absolute zero
Measurements with a recuperative superfluid stirling refrigerator
International Nuclear Information System (INIS)
Watanabe, A.; Swift, G.W.; Brisson, J.G.
1996-01-01
A superfluid Stirling refrigerator cooled to 168 mK using a 4.9 % 3 He- 4 He mixture and exhausting its waste heat at 383 mK. Cooling power versus temperature and speed is presented for 4.9%, 17%, and 36% mixtures. At the highest concentration, a dissipation mechanism of unknown origin is observed
Probing the upper limit of nonclassical rotational inertia in solid helium 4.
Rittner, Ann Sophie C; Reppy, John D
2008-10-10
We study the effect of confinement on solid 4He's nonclassical rotational inertia fraction (NCRIF) in a torsional oscillator by constraining it to narrow annular cells of various widths. The NCRIF exhibits an observed maximum value of 20% for annuli of approximately 100 microm width. Samples constrained to porous media or to larger geometries both have smaller NCRIF, mostly below approximately 1%. In addition, we extend the blocked-annulus experiment of Kim and Chan to solid samples with large supersolid fractions. Blocking the annulus suppresses the nonclassical decoupling from 17.1% to below the limit of our detection of 0.8%. This result demonstrates the nonlocal nature of the supersolid phenomena. At 20 mK, NCRIF depends on velocity history showing a closed hysteresis loop in different thin annular cells.
Nonsuperfluid origin of the nonclassical rotational inertia in a bulk sample of solid 4He.
Reppy, John D
2010-06-25
The torsional oscillator experiments described here examine the effect of disorder on the nonclassical rotational inertia (NCRI) of a solid 4He sample. The NCRI increases with increasing disorder, but the period changes responsible for this increase occur primarily at higher temperatures. Contrary to expectations based on a supersolid scenario, the oscillator period remains relatively unaffected at the lowest temperatures. This result points to a nonsuperfluid origin for the NCRI.
Counter-flow Induced Decoupling in Super-Fluid Turbulence
Khomenko, Dmytro; L'vov, Victor S.; Pomyalov, Anna; Procaccia, Itamar
2015-01-01
In mechanically driven superfluid turbulence the mean velocities of the normal- and superfluid components are known to coincide: $\\mathbf U_{\\text{n}} =\\mathbf U_{\\text{s}}$. Numerous laboratory, numerical and analytical studies showed that under these conditions the mutual friction between the normal- and superfluid velocity components couples also their fluctuations: $\\mathbf u'_{\\text{n}}(\\mathbf r,t) \\approx \\mathbf u'_{\\text{s}}(\\mathbf r,t)$ almost at all scales. In this paper we show t...
Superfluid Stirling-cycle refrigeration below 1 Kelvin
International Nuclear Information System (INIS)
Kotsubo, V.; Swift, G.W.
1991-01-01
A new method for cooling below 1 K, the superfluid Stirling cycle, uses the gaslike thermodynamic properties of the 3 He solute in a superfluid 3 He- 4 He solution. The first prototype superfluid Stirling-cycle refrigerator cools to 0.6 K from a starting temperature of 1.2 K, with cooling powers at the lowest temperatures of a few tens of microwatts. The cycle works in both classical-gas and Fermi-gas regimes
High temperature superconductors and other superfluids
Alexandrov, A S
2017-01-01
Written by eminent researchers in the field, this text describes the theory of superconductivity and superfluidity starting from liquid helium and a charged Bose-gas. It also discusses the modern bipolaron theory of strongly coupled superconductors, which explains the basic physical properties of high-temperature superconductors. This book will be of interest to fourth year graduate and postgraduate students, specialist libraries, information centres and chemists working in high-temperature superconductivity.
Vortices and sound waves in superfluids
Lee, Kimyeong
1994-01-01
We consider the dynamics of vortex strings and sound waves in superfluids in the phenomenological Landau-Ginzburg equation. We first derive the vortex equation where the velocity of a vortex is determined by the average fluid velocity and the density gradient near the vortex. We then derive the effective action for vortex strings and sound waves by the dual formulation. The effective action might be useful in calculating the emission rate of sound waves by moving vortex strings.
Superfluid response in heavy fermion superconductors
Zhong, Yin; Zhang, Lan; Shao, Can; Luo, Hong-Gang
2017-10-01
Motivated by a recent London penetration depth measurement [H. Kim, et al., Phys. Rev. Lett. 114, 027003 (2015)] and novel composite pairing scenario [O. Erten, R. Flint, and P. Coleman, Phys. Rev. Lett. 114, 027002 (2015)] of the Yb-doped heavy fermion superconductor CeCoIn5, we revisit the issue of superfluid response in the microscopic heavy fermion lattice model. However, from the literature, an explicit expression for the superfluid response function in heavy fermion superconductors is rare. In this paper, we investigate the superfluid density response function in the celebrated Kondo-Heisenberg model. To be specific, we derive the corresponding formalism from an effective fermionic large- N mean-field pairing Hamiltonian whose pairing interaction is assumed to originate from the effective local antiferromagnetic exchange interaction. Interestingly, we find that the physically correct, temperature-dependent superfluid density formula can only be obtained if the external electromagnetic field is directly coupled to the heavy fermion quasi-particle rather than the bare conduction electron or local moment. Such a unique feature emphasizes the key role of the Kondo-screening-renormalized heavy quasi-particle for low-temperature/energy thermodynamics and transport behaviors. As an important application, the theoretical result is compared to an experimental measurement in heavy fermion superconductors CeCoIn5 and Yb-doped Ce1- x Yb x CoIn5 with fairly good agreement and the transition of the pairing symmetry in the latter material is explained as a simple doping effect. In addition, the requisite formalism for the commonly encountered nonmagnetic impurity and non-local electrodynamic effect are developed. Inspired by the success in explaining classic 115-series heavy fermion superconductors, we expect the present theory will be applied to understand other heavy fermion superconductors such as CeCu2Si2 and more generic multi-band superconductors.
Superfluidity of bosons on a deformable lattice
International Nuclear Information System (INIS)
Jackeli, G.; Ranninger, J.
2001-01-01
We study the superfluid properties of a system of interacting bosons on a lattice, which, moreover, are coupled to the vibrational modes of this lattice, treated here in terms of Einstein phonon modes. The ground state corresponds to two correlated condensates: that of the bosons and that of the phonons. Two competing effects determine the common collective sound-wave-like mode with sound velocity v, arising from gauge symmetry breaking. (i) The sound velocity v 0 (corresponding to a weakly interacting Bose system on a rigid lattice) in the lowest-order approximation is reduced due to reduction of the repulsive boson-boson interaction, arising from the attractive part of the phonon-mediated interaction in the static limit. (ii) The second-order correction to the sound velocity is enhanced as compared to that of bosons on a rigid lattice when the boson-phonon interaction is switched on due to the retarded nature of the phonon-mediated interaction. The overall effect is that the sound velocity is essentially unaffected by the coupling with phonons, indicating the robustness of the superfluid state. The induction of a coherent state in the phonon system driven by the condensation of the bosons could be of experimental significance, permitting spectroscopic detection of superfluid properties of bosons. Our results are based on an extension of the Beliaev-Popov formalism for a weakly interacting Bose gas on a rigid lattice to one on a deformable lattice with which it interacts
Classical rotational inertia of solid 4He.
Dash, J G; Wettlaufer, J S
2005-06-17
The observation of reduced rotational inertia in a cell containing solid 4He has been interpreted as evidence for superfluidity of the solid. We propose an alternative explanation: slippage of the solid, due to grain boundary premelting between the solid and dense adsorbed layers at the container wall. We calculate the range of film thickness, and determine the viscosity that will account for the missing rotational inertia. Grain boundary premelting also explains inertial anomalies in an earlier study of solid helium in porous glass and indicates that the liquid is partially superfluid.
Induced interactions in a superfluid Bose-Fermi mixture
DEFF Research Database (Denmark)
Kinnunen, Jami; Bruun, Georg
2015-01-01
We analyze a Bose-Einstein condensate (BEC) mixed with a superfluid two-component Fermi gas in the whole BCS-BEC crossover. Using a quasiparticle random-phase approximation combined with Beliaev theory to describe the Fermi superfluid and the BEC, respectively, we show that the single...
Induced interactions in a superfluid Bose-Fermi mixture
DEFF Research Database (Denmark)
Kinnunen, Jami; Bruun, Georg
2015-01-01
We analyze a Bose-Einstein condensate (BEC) mixed with a superfluid two-component Fermi gas in the whole BCS-BEC crossover. Using a quasiparticle random-phase approximation combined with Beliaev theory to describe the Fermi superfluid and the BEC, respectively, we show that the single-particle an......We analyze a Bose-Einstein condensate (BEC) mixed with a superfluid two-component Fermi gas in the whole BCS-BEC crossover. Using a quasiparticle random-phase approximation combined with Beliaev theory to describe the Fermi superfluid and the BEC, respectively, we show that the single......-particle and collective excitations of the Fermi gas give rise to an induced interaction between the bosons, which varies strongly with momentum and frequency. It diverges at the sound mode of the Fermi superfluid, resulting in a sharp avoided crossing feature and a corresponding sign change of the interaction energy...
Atomic Evolution and Entanglement of Two Qubits in Photon Superfluid
Yin, Miao; Zhang, Xiongfeng; Deng, Yunlong; Deng, Huaqiu
2018-03-01
By using reservoir theory, we investigate the evolution of an atom placed in photon superfluid and study the entanglement properties of two qubits interacting with photon superfluid. It is found that the atomic decay rate in photon superfluid changes periodically with position of the atom and the decay rate can be inhibited compared to that in usual electromagnetic environment without photon superfluid. It is also found that when two atoms are separately immersed in their own local photon-superfluid reservoir, the entanglement sudden death or birth occurs or not only depends on the initial state of the qubits. What is more, we find a possible case that the concurrence between two qubits can remain a constant value by choosing proper values of parameters of the system, which may provide a new way to preserve quantum entanglement.
Vortex Lattices in the Bose-Fermi Superfluid Mixture.
Jiang, Yuzhu; Qi, Ran; Shi, Zhe-Yu; Zhai, Hui
2017-02-24
In this Letter we show that the vortex lattice structure in the Bose-Fermi superfluid mixture can undergo a sequence of structure transitions when the Fermi superfluid is tuned from the BCS regime to the BEC regime. This is due to the difference in the vortex core structure of a Fermi superfluid in the BCS regime and in the BEC regime. In the BCS regime the vortex core is nearly filled, while the density at the vortex core gradually decreases until it empties out in the BEC regime. Therefore, with the density-density interaction between the Bose and the Fermi superfluids, interaction between the two sets of vortex lattices gets stronger in the BEC regime, which yields the structure transition of vortex lattices. In view of the recent realization of this superfluid mixture and vortices therein, our theoretical predication can be verified experimentally in the near future.
Helicity conservation and twisted Seifert surfaces for superfluid vortices.
Salman, Hayder
2017-04-01
Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical derivation. This reveals that the spanwise vector that is used to characterize the twist contribution must point in the direction of a surface of constant velocity potential. An immediate consequence of the Seifert framing is that the continuum definition of helicity for a superfluid is trivially zero at all times. It follows that the Gauss-linking number is a more appropriate definition of helicity for superfluids. Despite this, we explain how a quasi-classical limit can arise in a superfluid in which the continuum definition for helicity can be used. This provides a clear connection between a microscopic and a macroscopic description of a superfluid as provided by the Hall-Vinen-Bekarevich-Khalatnikov equations. This leads to consistency with the definition of helicity used for classical vortices.
Vortex structure in superfluid color-flavor locked quark matter
Directory of Open Access Journals (Sweden)
Alford Mark G.
2016-01-01
Full Text Available The core region of a neutron star may feature quark matter in the color-flavor-locked (CFL phase. The CFL condensate breaks the baryon number symmetry, such that the phenomenon of superfluidity arises. If the core of the star is rotating, vortices will form in the superfluid, carrying the quanta of angular momentum. In a previous study we have solved the question of stability of these vortices, where we found numerical proof of a conjectured instability, according to which superfluid vortices will decay into an arrangement of so-called semi-superfluid fluxtubes. Here we report first results of an extension of our framework that allows us to study multi-vortex dynamics. This will in turn enable us to investigate the structure of semi-superfluid string lattices, which could be relevant to study pinning phenomena at the boundary of the core.
Probing and Manipulating Ultracold Fermi Superfluids
Jiang, Lei
Ultracold Fermi gas is an exciting field benefiting from atomic physics, optical physics and condensed matter physics. It covers many aspects of quantum mechanics. Here I introduce some of my work during my graduate study. We proposed an optical spectroscopic method based on electromagnetically-induced transparency (EIT) as a generic probing tool that provides valuable insights into the nature of Fermi paring in ultracold Fermi gases of two hyperfine states. This technique has the capability of allowing spectroscopic response to be determined in a nearly non-destructive manner and the whole spectrum may be obtained by scanning the probe laser frequency faster than the lifetime of the sample without re-preparing the atomic sample repeatedly. Both quasiparticle picture and pseudogap picture are constructed to facilitate the physical explanation of the pairing signature in the EIT spectra. Motivated by the prospect of realizing a Fermi gas of 40K atoms with a synthetic non-Abelian gauge field, we investigated theoretically BEC-HCS crossover physics in the presence of a Rashba spin-orbit coupling in a system of two-component Fermi gas with and without a Zeeman field that breaks the population balance. A new bound state (Rashba pair) emerges because of the spin-orbit interaction. We studied the properties of Rashba pairs using a standard pair fluctuation theory. As the two-fold spin degeneracy is lifted by spin-orbit interaction, bound pairs with mixed singlet and triplet pairings (referred to as rashbons) emerge, leading to an anisotropic superfluid. We discussed in detail the experimental signatures for observing the condensation of Rashba pairs by calculating various physical observables which characterize the properties of the system and can be measured in experiment. The role of impurities as experimental probes in the detection of quantum material properties is well appreciated. Here we studied the effect of a single classical impurity in trapped ultracold Fermi
Nonlinear acoustic interactions in superfluid helium
International Nuclear Information System (INIS)
Wright, D.R.
1989-01-01
Studies of nonlinear acoustic interactions in superfluid helium at temperatures below 0.2 degree K have culminated in the construction of an all-acoustic parametric amplifier at gigahertz frequencies. This amplifier represents the shortest wavelength parametric amplifier ever made, with signal wavelengths shorter than 1000 angstrom and pump wavelengths shorter than 600 angstrom. Begun as part of a program to extend the frequency range, and hence improve the resolution, of the scanning acoustic microscope while maintaining an adequate signal-to-noise ratio, the early work on nonlinearity concentrated on the very high power densities achieved at the focus of an acoustic lens. In a pressure range where the dispersion forbids three-phonon processes, indirect evidence of four-phonon mixing is observed. In the parametric amplifier experiment, plane waves are mixed at a predefined angle in the superfluid helium. Two gain regimes are observed. The first regime is a four-phonon collinear process, in which gain on the signal is created by the second-harmonic of the pump. The second regime is a noncollinear phase-matched process, in which the signal phonon stimulates decay of the pump phonon to create gain at the signal frequency
Luttinger's theorem, superfluid vortices and holography
Iqbal, Nabil; Liu, Hong
2012-10-01
Strongly coupled field theories with gravity duals can be placed at finite density in two ways: electric field flux emanating from behind a horizon, or bulk charged fields outside of the horizon that explicitly source the density. We discuss field-theoretical observables that are sensitive to this distinction. If the charged fields are fermionic, we discuss a modified Luttinger's theorem that holds for holographic systems, in which the sum of boundary theory Fermi surfaces counts only the charge outside of the horizon. If the charged fields are bosonic, we show that the resulting superfluid phase may be characterized by the coefficient of the transverse Magnus force on a moving superfluid vortex, which again is sensitive only to the charge outside of the horizon. For holographic systems, these observables provide a field-theoretical way to distinguish how much charge is held by a dual horizon, but they may be useful in more general contexts as measures of deconfined (i.e. ‘fractionalized’) charge degrees of freedom.
Superfluidity, Bose condensation and neutron scattering in liquid 4He
International Nuclear Information System (INIS)
Silver, R.N.
1997-01-01
The relation between superfluidity and Bose condensation in 4 He provides lessons that may be valuable in understanding the strongly correlated electron system of high T c superconductivity. Direct observation of a Bose condensate in the superfluid by deep inelastic neutron scattering measurements has been attempted over many years. But the impulse approximation, which relates momentum distributions to neutron scattering structure functions, is broadened by final state effects. Nevertheless, the excellent quantitative agreement between ab initio quantum many body theory and high precision neutron experiments provides confidence in the connection between superfluidity and Bose condensation
A hydrodynamic model for superfluid helium with vortices
International Nuclear Information System (INIS)
Lhuillier, D.; Francois, M.
1975-01-01
Although their existence is experimentally well verified, the so-called mutual friction force Fsub(sn) and superfluid friction force Fsub(s) cannot emerge from the Landau irrotational model of superfluidity. Up to now these forces have merely been added to the Landau equations but this is untenable since, as a consequence, one destroys the irrotationality condition with which the equations have expressly been built. It is shown that these friction forces appear in a natural way in a model where superfluid helium with vortices is compared to a fluid with a conserved intrinsic momentum. (Auth.)
Thermodynamics of the superfluid dilute Bose gas with disorder
International Nuclear Information System (INIS)
Lopatin, A.V.; Vinokur, V.M.
2002-01-01
We generalize the Beliaev-Popov diagrammatic technique for the problem of interacting dilute Bose gas with weak disorder. Averaging over disorder is implemented by the replica method. The low-energy asymptotic form of the Green function confirms that the low-energy excitations of the superfluid dirty-boson system are sound waves with velocity renormalized by the disorder and additional dissipation due to the impurity scattering. We find the thermodynamic potential and the superfluid density at any temperature below the superfluid transition temperature (but outside the Ginzburg region) and derive the phase diagram in temperature vs disorder plane
Identifying a Superfluid Reynolds Number via Dynamical Similarity.
Reeves, M T; Billam, T P; Anderson, B P; Bradley, A S
2015-04-17
The Reynolds number provides a characterization of the transition to turbulent flow, with wide application in classical fluid dynamics. Identifying such a parameter in superfluid systems is challenging due to their fundamentally inviscid nature. Performing a systematic study of superfluid cylinder wakes in two dimensions, we observe dynamical similarity of the frequency of vortex shedding by a cylindrical obstacle. The universality of the turbulent wake dynamics is revealed by expressing shedding frequencies in terms of an appropriately defined superfluid Reynolds number, Re(s), that accounts for the breakdown of superfluid flow through quantum vortex shedding. For large obstacles, the dimensionless shedding frequency exhibits a universal form that is well-fitted by a classical empirical relation. In this regime the transition to turbulence occurs at Re(s)≈0.7, irrespective of obstacle width.
The extension of radiative viscosity to superfluid matter
Pi, Chun-Mei; Yang, Shu-Hua; Zheng, Xiao-Ping
2010-01-01
The radiative viscosity of superfluid $npe$ matter is studied, and it is found that to the lowest order of $\\delta \\mu/T$ the ratio of radiative viscosity to bulk viscosity is the same as that of the normal matter.
Superfluidity (a bibliography with abstracts). Report for 1964--Feb 1976
International Nuclear Information System (INIS)
Reimherr, G.W.
1976-03-01
The cited reports discuss superfluidity in liquid helium, with both helium 3 and helium 4 considered. Topics discussed include phase studies, heat transfer, hydrodynamics, rotons, zero sound, first sound, second sound, third sound, and fourth sound. (Contains 142 abstracts)
Quench from Mott Insulator to Superfluid
Energy Technology Data Exchange (ETDEWEB)
Zurek, Wojciech H. [Los Alamos National Laboratory; Dziarmaga, Jacek [Instytut Fizyki Uniwersytetu Jagiello´nskiego; Tylutki, Marek [Instytut Fizyki Uniwersytetu Jagiello´nskiego
2012-06-01
We study a linear ramp of the nearest-neighbor tunneling rate in the Bose-Hubbard model driving the system from the Mott insulator state into the superfluid phase. We employ the truncated Wigner approximation to simulate linear quenches of a uniform system in 1...3 dimensions, and in a harmonic trap in 3 dimensions. In all these setups the excitation energy decays like one over third root of the quench time. The -1/3 scaling is explained by an impulse-adiabatic approximation - a variant of the Kibble-Zurek mechanism - describing a crossover from non-adiabatic to adiabatic evolution when the system begins to keep pace with the increasing tunneling rate.
Monopole Strength Function of Deformed Superfluid Nuclei
Energy Technology Data Exchange (ETDEWEB)
Stoitsov, M. V. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Kortelainen, E. M. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Nakatsukasa, T. [RIKEN, Japan; Losa, C. [International School for Advanced Studies (SISSA), Trieste, Italy; Nazarewicz, Witold [ORNL
2011-01-01
We present an efficient method for calculating strength functions using the finite amplitude method (FAM) for deformed superfluid heavy nuclei within the framework of the nuclear density functional theory. We demonstrate that FAM reproduces strength functions obtained with the fully self-consistent quasi-particle random-phase approximation (QRPA) at a fraction of computational cost. As a demonstration, we compute the isoscalar and isovector monopole strength for strongly deformed configurations in ^{240}Pu by considering huge quasi-particle QRPA spaces. Our approach to FAM, based on Broyden's iterative procedure, opens the possibility for large-scale calculations of strength distributions in well-bound and weakly bound nuclei across the nuclear landscape.
Geometric symmetries in superfluid vortex dynamics
Kozik, Evgeny; Svistunov, Boris
2010-10-01
Dynamics of quantized vortex lines in a superfluid feature symmetries associated with the geometric character of the complex-valued field, w(z)=x(z)+iy(z) , describing the instant shape of the line. Along with a natural set of Noether’s constants of motion, which—apart from their rather specific expressions in terms of w(z) —are nothing but components of the total linear and angular momenta of the fluid, the geometric symmetry brings about crucial consequences for kinetics of distortion waves on the vortex lines, the Kelvin waves. It is the geometric symmetry that renders Kelvin-wave cascade local in the wave-number space. Similar considerations apply to other systems with purely geometric degrees of freedom.
Search for Majorana Fermions in S-Wave Fermionic Superfluids
2016-04-01
respect to the in-plane Zeeman field. (Right) The quasiparticle excitation at the critical point from normal superfluids to topological superfluids...instead of a normal metal lead can suppress the thermal broadening effects in tunneling conductance from Majorana fermions, helping reveal the quantized...utilizing two additional components: spin-orbit coupling and Zeeman fields. In the last year grant period, we have made the following important
Self-energy dispersion effects on neutron matter superfluidity
International Nuclear Information System (INIS)
Zuo Wei
2001-01-01
The effects of the dispersion and ground state correlation of the single particle self-energy on neutron matter superfluidity have been investigated in the framework of the Extended Brueckner-Hartree-Fock and the generalized BCS approaches. A sizable reduction of the energy gap is found due to the energy dependence of the self-energy. And the inclusion of the ground state correlations in the self-energy suppresses further the neutron matter superfluidity
Electric dipole moment and spin supercurrent in superfluid 3He
International Nuclear Information System (INIS)
Mineev, V.P.; Volovik, G.E.
1992-01-01
The SU(2) gauge invariant theory of the relativistic interaction of the electrically neutral superfluid 3 He with electric and magnetic fields is formulated. The spin supercurrent response on the electric field is calculated for this interaction. The comparison with the nonrelativistic flexoelectric effect, arising due to the distortion of the atomic shell by the gradients of the superfluid order parameter, is made. 5 refs
Instability of superfluid flow in the neutron star core
Link, B.
2012-04-01
Pinning of superfluid vortices to magnetic flux tubes in the outer core of a neutron star supports a velocity difference of ˜105 cm s-1 between the neutron superfluid and the proton-electron fluid as the star spins down. Under the Magnus force that arises on the vortex array, vortices undergo vortex creep through thermal activation or quantum tunnelling. We examine the hydrodynamic stability of this situation. Vortex creep introduces two low-frequency modes, one of which is unstable above a critical wavenumber for any non-zero flow velocity of the neutron superfluid with respect to the charged fluid. For typical pinning parameters of the outer core, the superfluid flow is unstable over wavelengths λ≲ 10 m and over time-scales of ˜(λ/1 m)1/2 yr down to ˜1 d. The vortex lattice could degenerate into a tangle, and the superfluid flow would become turbulent. We suggest that superfluid turbulence could be responsible for the red timing noise seen in many neutron stars, and find a predicted spectrum that is generally consistent with observations.
Anderson's considerations on the flow of superfluid helium: Some offshoots
Varoquaux, Eric
2015-07-01
Nearly five decades have elapsed since the seminal 1966 paper of P. W. Anderson on the flow of superfluid helium, 4He at that time. Some of his "considerations"—the role of the quantum phase as a dynamical variable, the interplay between the motion of quantized vortices and potential superflow, its incidence on dissipation in the superfluid and the appearance of critical velocities, the quest for the hydrodynamic analogs of the Josephson effects in helium—and the way they have evolved over the past half century are recounted in this review. But it is due to key advances on the experimental front that phase slippage could be harnessed in the laboratory, leading to a deeper understanding of superflow, vortex nucleation, the various intrinsic and extrinsic dissipation mechanisms in superfluids, macroscopic quantum effects, and the superfluid analog of both ac and dc Josephson effects—pivotal concepts in superfluid physics—have been performed. Some of the experiments that have shed light on the more intimate effect of quantum mechanics on the hydrodynamics of the dense heliums are surveyed, including the nucleation of quantized vortices both by Arrhenius processes and by macroscopic quantum tunneling, the setting up of vortex mills, and superfluid interferometry.
Renormalization group approach to superfluid neutron matter
International Nuclear Information System (INIS)
Hebeler, K.
2007-01-01
In the present thesis superfluid many-fermion systems are investigated in the framework of the Renormalization Group (RG). Starting from an experimentally determined two-body interaction this scheme provides a microscopic approach to strongly correlated many-body systems at low temperatures. The fundamental objects under investigation are the two-point and the four-point vertex functions. We show that explicit results for simple separable interactions on BCS-level can be reproduced in the RG framework to high accuracy. Furthermore the RG approach can immediately be applied to general realistic interaction models. In particular, we show how the complexity of the many-body problem can be reduced systematically by combining different RG schemes. Apart from technical convenience the RG framework has conceptual advantage that correlations beyond the BCS level can be incorporated in the flow equations in a systematic way. In this case however the flow equations are no more explicit equations like at BCS level but instead a coupled set of implicit equations. We show on the basis of explicit calculations for the single-channel case the efficacy of an iterative approach to this system. The generalization of this strategy provides a promising strategy for a non-perturbative treatment of the coupled channel problem. By the coupling of the flow equations of the two-point and four-point vertex self-consistency on the one-body level is guaranteed at every cutoff scale. (orig.)
Experiments of superfluid 4He evaporation
International Nuclear Information System (INIS)
Balibar, S.; Buechner, J.; Castaing, B.; Laroche, C.; Libchaber, A.
1978-01-01
A study of the evaporation of superfluid 4 He using the heat-pulse technique, is presented; working at low temperature, 0.1 0 K, the phonon and the roton fluids are decoupled. We observed atoms evaporated by a phonon second-sound pulse between 0.4 and 0.6 0 K. The temperature dependence of the signal is interpreted by a simple model where one phonon of energy E emits one atom of energy E - E 0 (E 0 = 7.15 0 K is the atomic binding energy in the liquid). At lower temperature, down to 0.1 0 K, a ballistic-phonon regime is observed, associated with no detected evaporation. Concerning rotons, we observe well-defined signals due to atoms evaporated by them. Analyzing the arrival time as a function of the liquid path, we propose an evaporation process such as one roton of energy E emits one atom of energy E - e 0 . This leads to a minimum kinetic energy of 1.5 0 K for the evaporated atoms, effectively observed. An estimation of the roton mean free path is deduced and a maximum roton velocity of 160 +- 10 m sec -1 is observed
Renormalization group approach to superfluid neutron matter
Energy Technology Data Exchange (ETDEWEB)
Hebeler, K.
2007-06-06
In the present thesis superfluid many-fermion systems are investigated in the framework of the Renormalization Group (RG). Starting from an experimentally determined two-body interaction this scheme provides a microscopic approach to strongly correlated many-body systems at low temperatures. The fundamental objects under investigation are the two-point and the four-point vertex functions. We show that explicit results for simple separable interactions on BCS-level can be reproduced in the RG framework to high accuracy. Furthermore the RG approach can immediately be applied to general realistic interaction models. In particular, we show how the complexity of the many-body problem can be reduced systematically by combining different RG schemes. Apart from technical convenience the RG framework has conceptual advantage that correlations beyond the BCS level can be incorporated in the flow equations in a systematic way. In this case however the flow equations are no more explicit equations like at BCS level but instead a coupled set of implicit equations. We show on the basis of explicit calculations for the single-channel case the efficacy of an iterative approach to this system. The generalization of this strategy provides a promising strategy for a non-perturbative treatment of the coupled channel problem. By the coupling of the flow equations of the two-point and four-point vertex self-consistency on the one-body level is guaranteed at every cutoff scale. (orig.)
Cooling of Compact Stars with Nucleon Superfluidity and Quark Superconductivity
Noda, Tsuneo; Hashimoto, Masa-aki; Yasutake, Nobutoshi; Maruyama, Toshiki; Tatsumi, Toshitaka
We show a cooling scenario of compact stars to satisfy recent observations of compact stars. The central density of compact stars can exceed the nuclear density, and it is considered that many hadronic phases appear at such a density. It is discussed that neutron superfluidity (1S0 for lower density, and 3P2 for higher density) and proton superfluidity/superconductivity (1S0) appears in all compact stars. And some "Exotic" states are considered to appear in compact stars, such as meson condensation, hyperon mixing, deconfinement of quarks and quark colour superconductivity. These exotic states appear at the density region above the threshold densities of each state. We demonstrate the thermal evolution of isolated compact stars, adopting the effects of nucleon superfluidity and quark colour superconductivity. We assume large gap energy (Δ > 10 MeV) for colour superconducting quark phase, and include the effects of nucleon superfluidity with parametrised models. We simulate the cooling history of compact stars, and shows that the heavier star does not always cool faster than lighter one, which is determined by the parameters of neutron 3P2 superfluidity.
Energy Technology Data Exchange (ETDEWEB)
Baudouy, B
1996-10-04
Heat transfer studies of electrical cable insulation in superconducting winding are of major importance for stability studies in superconducting magnets. This work presents an experimental heat transfer study in superconducting cables of Large Hadron Collider dipoles cooled by superfluid helium and submitted to volume heat dissipation due to beam losses. For NbTi magnets cooled by superfluid helium the most severe heat barrier comes from the electrical insulation of the cables. Heat behaviour of a winding is approached through an experimental model in which insulation characteristics can be modified. Different tests on insulation patterns show that heat transfer is influenced by superfluid helium contained in insulation even for small volume of helium (2 % of cable volume). Electrical insulation can be considered as a composite material made of a solid matrix with a helium channels network which cannot be modelled easily. This network is characterised by another experimental apparatus which allows to study transverse and steady-state heat transfer through an elementary insulation pattern. Measurements in Landau regime ({delta}T{approx}10{sup -5} to 10{sup -3} K) and in Gorter-Mellink regime ({delta}T>10{sup -3} K) and using assumptions that helium thermal paths and conduction in the insulation are decoupled allow to determine an equivalent channel area (10{sup -6} m{sup 2}) and an equivalent channel diameter (25 {mu}). (author)
On the disappearance of superfluidity in helium films
International Nuclear Information System (INIS)
Bannink, G.
1983-01-01
Experiments to investigate the changes in superfluid properties when helium films become thinner are reported. A thin-film oscillator, formed by two large filmreservoirs connected by a long and narrow tube, is used to study both the mass transport properties and the third-sound phenomena. Both sets of data are analysed in the framework of a two-fluid model. Absolute values for the areal superfluid density are deduced from the results, and also the observation of friction in the film itself is briefly discussed. A series of additional measurements of the thermo-mechanical effect in the reservoirs, with the purpose of determing the thickness at which onset of superfluidity occurs, are also reported. Finally the overall picture of the film properties is discussed on the basis of a phase diagram of the observed mobilities. (Auth.)
Laszlo Tisza and the two-fluid model of superfluidity
Balibar, Sébastien
2017-11-01
The "two-fluid model" of superfluidity was first introduced by Laszlo Tisza in 1938. On that year, Tisza published the principles of his model as a brief note in Nature and two articles in French in the Comptes rendus de l'Académie des sciences, followed in 1940 by two other articles in French in the Journal de physique et le Radium. In 1941, the two-fluid model was reformulated by Lev Landau on a more rigorous basis. Successive experiments confirmed the revolutionary idea introduced by Tisza: superfluid helium is indeed a surprising mixture of two fluids with independent velocity fields. His prediction of the existence of heat waves, a consequence of his model, was also confirmed. Then, it took several decades for the superfluidity of liquid helium to be fully understood.
Vortex annihilation and inverse cascades in two dimensional superfluid turbulence
Lucas, Andrew; Chesler, Paul M.
2015-03-01
The dynamics of a dilute mixture of vortices and antivortices in a turbulent two-dimensional superfluid at finite temperature is well described by first order Hall-Vinen-Iordanskii equations, or dissipative point vortex dynamics. These equations are governed by a single dimensionless parameter: the ratio of the strength of drag forces to Magnus forces on vortices. When this parameter is small, we demonstrate using numerical simulations that the resulting superfluid enjoys an inverse energy cascade where small scale stirring leads to large scale vortex clustering. We argue analytically and numerically that the vortex annihilation rate in a laminar flow may be parametrically smaller than the rate in a turbulent flow with an inverse cascade. This suggests a new way to detect inverse cascades in experiments on two-dimensional superfluid turbulence using cold atomic gases, where traditional probes of turbulence such as the energy spectrum are not currently accessible.
Hidden vortex lattices in a thermally paired superfluid
International Nuclear Information System (INIS)
Dahl, E. K.; Sudboe, A.; Babaev, E.
2008-01-01
We study the evolution of rotational response of a statistical mechanical model of two-component superfluid with a nondissipative drag interaction as the system undergoes a transition into a paired superfluid phase at finite temperature. The transition manifests itself in a change of (i) vortex-lattice symmetry and (ii) nature of the vortex state. Instead of a vortex lattice, the system forms a highly disordered tangle which constantly undergoes merger and reconnecting processes involving different types of vortices with a 'hidden' breakdown of translation symmetry
A Note on the Field-Theoretical Description of Superfluids
Andrianopoli, L; Grassi, P A; Trigiante, M
2014-01-01
Recently, a Lagrangian description of superfluids attracted some interest from the fluid/gravity-correspondence viewpoint. In this respect, the work of Dubovksy et al. has proposed a new field theoretical description of fluids, which has several interesting aspects. On another side, we have provided in arXiv:1304.2206 a supersymmetric extension of the original works. In the analysis of the Lagrangian structures a new invariant appeared which, although related to known invariants, provides, in our opinion, a better parametrisation of the fluid dynamics in order to describe the fluid/superfluid phases.
Critical behavior of superfluid {sup 4}He in aerogel
Energy Technology Data Exchange (ETDEWEB)
Moon, K. [Department of Physics, University of California, Davis, California 95616 (United States); Girvin, S.M. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)
1995-08-14
We report Monte Carlo studies of the critical behavior of superfluid {sup 4}He in the presence of quenched disorder with long-range fractal correlations. Modeling aerogel as an incipient percolating cluster in 3D and weakening the bonds at the fractal sites, {ital XY}-model simulations demonstrate an increase in the superfluid density exponent {zeta} from 0.67{plus_minus}0.005 for the pure case to an apparent value of 0.722{plus_minus}0.005 in the presence of the fractal disorder, provided that the helium correlation length does not exceed the fractal correlation length.
Three Dimensional Characterization of Quantum Vortex Dynamics in Superfluid Helium
Meichle, David; Lathrop, Daniel
2015-03-01
Vorticity is constrained to line-like topological defects in quantum superfluids, such as liquid Helium below the Lambda transition. We have invented a novel method to disperse fluorescent nanoparticles directly into the superfluid which become trapped on the vortex cores, providing optical tracers. Using a newly constructed multi-camera stereographic microscope, we present data dynamically characterizing vortex reconnections and the subsequent emission of Kelvin waves fully in three dimensions. Statistics of thermally driven counterflow will be compared in 3D to previous measurements in projection.
Mobility of negative ions in superfluid 3He
International Nuclear Information System (INIS)
Ahonen, A.I.; Kokko, J.; Lounasmaa, O.V.; Paalanen, M.A.; Richardson, R.C.; Schoepe, W.; Takano, Y.
1977-01-01
The mobility of negative ions is shown to increase rapidly below T/sub c/ in both superfluid 3 He phases. The ratio μ/μ/sub N/ of superfluid to normal mobility is larger in the B phase than in the A phase. A critical velocity consistent in magnitude with the Landau limit for pair breaking has also been observed. In the normal fluid we find a temperature independent mobility between 40 mK and T/sub c/ for all pressures between 0 and 28 bar. The increase of μ/sub N/ with increasing pressure is in agreement with the bubble model for the negative ion
Decay of superfluid turbulence via Kelvin-wave radiation
International Nuclear Information System (INIS)
Leadbeater, M.; Adams, C.S.; Samuels, D.C.; Barenghi, C.F.
2003-01-01
The decay of superfluid turbulence in the limit of low temperature is studied by numerical simulations of vortex ring collisions. In particular we excite Kelvin waves and study the loss of vortex line length due to Kelvin-wave radiation. Although the effect is small, the decay constant is not inconsistent with recent experiments on vortex lattices in dilute Bose-Einstein condensates, and on superfluid turbulence in helium at very low temperature. We also consider the character of the decay when both vortex reconnections and Kelvin-wave radiation are present
Kelvin-wave cascade and decay of superfluid turbulence
International Nuclear Information System (INIS)
Kozik, Evgeny; Svistunov, Boris
2004-01-01
Kelvin waves (kelvons), the distortion waves on vortex lines, play a key part in the relaxation of superfluid turbulence at low temperatures. We present a weak-turbulence theory of kelvons. We show that nontrivial kinetics arises only beyond the local-induction approximation and is governed by three-kelvon collisions; a corresponding kinetic equation is derived. We prove the existence of Kolmogorov cascade and find its spectrum. The qualitative analysis is corroborated by numeric study of the kinetic equation. The application of the results to the theory of superfluid turbulence is discussed
Mobility of negative ions in superfluid 3He
International Nuclear Information System (INIS)
Ahonen, A.I.; Kokko, J.; Lounasmaa, O.V.; Paalanen, M.A.; Richardson, R.C.; Schoepe, W.; Takano, Y.
1976-01-01
We have found that the mobility of negative ions increases rapidly below T/sub c/ in both superfluid 3 He phases. The ratio μ/μ/sub N/ of superfluid to normal mobility is larger in the B phase than in the A phase. A critical velocity consistent in magnitude with the Landau limit for pair breaking has also been observed. In the normal fluid we find a temperature-independent mobility between 30 mK and T/sub c/ for all pressures between 0 and 28 bars
Relaxation of superfluid vortex bundles via energy transfer to the normal fluid
International Nuclear Information System (INIS)
Kivotides, Demosthenes
2007-01-01
We apply numerical and computational analyses to the decay of a topologically nontrivial, bundle-structured superfluid vortex tangle via mutual friction effected energy transfer to an initially stationary, viscous normal fluid. We demonstrate that, as long as the coherent superfluid vorticity structures remain intact, the induced normal-fluid vorticity acquires a similar to the superfluid vorticity morphology, and the normal-fluid energy spectrum mimics the superfluid energy spectrum presenting a low-wavenumber scaling regime. After a (smaller than the integral advective time scale) transient, the superfluid vorticity bundles disintegrate; this is followed by the decay of normal-fluid energy. The kinetic energies of the two fluids are mismatched throughout the decay period, and the dismantling of coherent vorticity destroys the low-wavenumber energy spectrum scaling in both fluids. At the point of maximum normal-fluid energy, the circulation of the induced normal-fluid vortices is comparable to the ''macroscopic'' circulation of the superfluid vorticity bundles. We show that the superfluid dynamics are dominated throughout the decay period by inertial rather than mutual friction effects, that the formation of bundlelike coherent superfluid vortices cannot be the outcome of pure (reconnecting) Biot-Savart dynamics, and that superfluid vortex length dynamics are not analogous to superfluid energy dynamics. We conjecture that the dynamics of fully developed, turbulent thermal superfluid flow could be described in terms of interactions of cyclic coherent vorticity patterns in both fluids
Relativistic mean field model for entrainment in general relativistic superfluid neutron stars
International Nuclear Information System (INIS)
Comer, G.L.; Joynt, R.
2003-01-01
General relativistic superfluid neutron stars have a significantly more intricate dynamics than their ordinary fluid counterparts. Superfluidity allows different superfluid (and superconducting) species of particles to have independent fluid flows, a consequence of which is that the fluid equations of motion contain as many fluid element velocities as superfluid species. Whenever the particles of one superfluid interact with those of another, the momentum of each superfluid will be a linear combination of both superfluid velocities. This leads to the so-called entrainment effect whereby the motion of one superfluid will induce a momentum in the other superfluid. We have constructed a fully relativistic model for entrainment between superfluid neutrons and superconducting protons using a relativistic σ-ω mean field model for the nucleons and their interactions. In this context there are two notions of 'relativistic': relativistic motion of the individual nucleons with respect to a local region of the star (i.e. a fluid element containing, say, an Avogadro's number of particles), and the motion of fluid elements with respect to the rest of the star. While it is the case that the fluid elements will typically maintain average speeds at a fraction of that of light, the supranuclear densities in the core of a neutron star can make the nucleons themselves have quite high average speeds within each fluid element. The formalism is applied to the problem of slowly rotating superfluid neutron star configurations, a distinguishing characteristic being that the neutrons can rotate at a rate different from that of the protons
Theory of third sound in a compressible and layered superfluid
International Nuclear Information System (INIS)
Puff, R.D.; Dash, J.G.
1980-01-01
This paper examines the theory of third sound, without attenuation effects, in layered superfluid films with finite compressibility. This theory, together with the application of a simple thermodynamic model for the film layers shows how the third-sound velocity can undergo strong variations with coverage associated with progressive changes in film compressibility, in-layer phase changes, and layer completion
Boson localization and the superfluid-insulator transition
International Nuclear Information System (INIS)
Fisher, M.P.A.; Weichman, P.B.; Grinstein, G.; Fisher, D.S.; Condensed Matter Physics 114-36, California Institute of Technology, Pasadena, California 91125; IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598; Joseph Henry Laboratory of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544)
1989-01-01
The phase diagrams and phase transitions of bosons with short-ranged repulsive interactions moving in periodic and/or random external potentials at zero temperature are investigated with emphasis on the superfluid-insulator transition induced by varying a parameter such as the density. Bosons in periodic potentials (e.g., on a lattice) at T=0 exhibit two types of phases: a superfluid phase and Mott insulating phases characterized by integer (or commensurate) boson densities, by the existence of a gap for particle-hole excitations, and by zero compressibility. Generically, the superfluid onset transition in d dimensions from a Mott insulator to superfluidity is ''ideal,'' or mean field in character, but at special multicritical points with particle-hole symmetry it is in the universality class of the (d+1)-dimensional XY model. In the presence of disorder, a third, ''Bose glass'' phase exists. This phase is insulating because of the localization effects of the randomness and analogous to the Fermi glass phase of interacting fermions in a strongly disordered potential
Topological px+ipy superfluid phase of fermionic polar molecules
Levinsen, J.; Cooper, N.R.; Shlyapnikov, G.V.
2011-01-01
We discuss the topological px+ipy superfluid phase in a 2D gas of single-component fermionic polar molecules dressed by a circularly polarized microwave field. This phase emerges because the molecules may interact with each other via a potential Vo(r) that has an attractive dipole-dipole 1/r^3 tail,
Thermal transport and dissipation in two dimensional superfluid 4He
International Nuclear Information System (INIS)
Joseph, R.A.
1982-01-01
The thermal conductivity of unsaturated helium films on a stainless steel substrate near the super-fluid transition has been examined, both as a function of temperature and as a function of heat carried by film. The terms of vortex dynamics as calculated by Ambegaokar, Halperin, Nelson, and Siggia (AHNS). Near the superfluid transitions it was found that the thermal conductivity increases with decreasing temperature in a manner similar to what would be expected on the basis of the AHNS theory. Below the superfluid transition, the determination of the dependence of thermal conductivity on superfluid velocity differs from the dependence expected on the basis of the AHNS theory. Also, the specific heat of helium in filled pores of Vycor glass has been examined. The temperature range in which rho/sub s/ is known to vanish with 2/3 power law has been studied in detail. No singularity was found in the specific heat. The data have been analyzed in terms of finite size scaling theory and two-scale factor universality
Quantum vortex dynamics in two-dimensional neutral superfluids
Wang, C. -C J.; Duine, R.A.; MacDonald, A.H.
2010-01-01
We derive an effective action for the vortex-position degree of freedom in a superfluid by integrating out condensate phase- and density-fluctuation environmental modes. When the quantum dynamics of environmental fluctuations is neglected, we confirm the occurrence of the vortex Magnus force and
Slowly rotating general relativistic superfluid neutron stars with relativistic entrainment
International Nuclear Information System (INIS)
Comer, G.L.
2004-01-01
Neutron stars that are cold enough should have two or more superfluids or supercondutors in their inner crusts and cores. The implication of superfluidity or superconductivity for equilibrium and dynamical neutron star states is that each individual particle species that forms a condensate must have its own, independent number density current and equation of motion that determines that current. An important consequence of the quasiparticle nature of each condensate is the so-called entrainment effect; i.e., the momentum of a condensate is a linear combination of its own current and those of the other condensates. We present here the first fully relativistic modeling of slowly rotating superfluid neutron stars with entrainment that is accurate to the second-order in the rotation rates. The stars consist of superfluid neutrons, superconducting protons, and a highly degenerate, relativistic gas of electrons. We use a relativistic σ-ω mean field model for the equation of state of the matter and the entrainment. We determine the effect of a relative rotation between the neutrons and protons on a star's total mass, shape, and Kepler, mass-shedding limit
The mobility of negative ions in superfluid 3He
International Nuclear Information System (INIS)
Solomaa, M.
1982-01-01
This article reviews recent experimental and theoretical work on the mobility of negative ions in the superfluid A and B phases of liquid 3 He. In the normal Fermi liquid at temperatures below approximately 50 mK and also in the superfluid close to the superfluid transition temperature, Tsub(c), the mobility of a negative ion may simply be considered as limited by the elastic scattering of 3 He quasiparticles. This explains the constancy of the ion mobility in the normal phase. However, underlying the rapid increase of the measured mobility in the superfluid phases there is a subtle quantum-mechanical scattering effect. Detailed solutions of the 3 He quasiparticle-negative ion scattering process in the pair-correlated state provide a simple physical picture of an energy-dependent forward-peaking phenomenon. This yields quantitative theoretical results for the ion mobility in the quasi-isotropic B phase and for the ion mobility tensor in the anisotropic A phase which agree with the experimental data. (author)
Briton wins Nobel physics prize for work on superfluids
Connor, S
2003-01-01
A British born scientist, Anthony Leggett, 65, has jointly won this year's Nobel prize in physics for research into the arcane area of superfluids - when matter behaves in its lowest and most ordered state. He shares the 800,000 pounds prize with two Russian physicists who have worked in the field of superconductivity - when electrical conductors lose resistance (1/2 page).
Transformation of second sound into surface waves in superfluid helium
International Nuclear Information System (INIS)
Khalatnikov, I.M.; Kolmakov, G.V.; Pokrovsky, V.L.
1995-01-01
The Hamiltonian theory of superfluid liquid with a free boundary is developed. Nonlinear amplitudes of parametric Cherenkov radiation of a surface wave by second sound and the inner decay of second sound waves are found. Threshold amplitudes of second sound waves for these two processes are determined. 4 refs
Superfluidity in 3He-4He mixture thin films
International Nuclear Information System (INIS)
Webster, E.
1980-01-01
All results from our experiments studying superfluidity in 3 He- 4 He mixture films are presented. Our measurements spanned the temperature range from 1.3 to 1.8K, and up to 30% 3 He molar concentration in the film. Films of up to 100 Angstroms thickness were studied. The experimental configuration and procedure are described. Relevant theories are reviewed. The areal superfluid mass density sigma/sub s/ is given in terms of an experimental measure of the film thickenss - sigma/rho(#betta#,T) - for all concentrations and temperatures studied. Detailed data from the onset regions are included. Precipitious onset phenomena were observed, and the Kosterlitz-Thouless-Nelson theory conclusively verified. However, no two-dimensional phase separation was observed, showing that mixture theories based on the X-Y model need additional refinement to correctly describe multilayer films. Experimental values of the superfluid onset and intercept (sigma/sub s/ extrapolated to zero) thicknesses of 3 He- 4 He mixture films are also exhibited. The latter (intercept) thickness is interpreted as a measure of the healing length, and alternatively as an excess normal fluid present in superfluid films. Analysis of our experimental evidence indicates that this excess normal fluid is due to surface roton excitations which exist at the substrate boundary, with an energy gap of 4.5 0 K
Continuous magnetic refrigeration in the superfluid helium range
International Nuclear Information System (INIS)
Lacaze, Alain.
1982-10-01
An experimental prototype magnetic refrigerator based on the well known adiabatic demagnetization principle is described. A continuous process is employed in which gadolinium garnet follows successive magnetization-demagnetization cycles between a hot liquid helium source at 4.2K and a cold superfluid helium source at T [fr
Transport and extraction of radioactive ions stopped in superfluid helium
Huang, WX; Dendooven, P; Gloos, K; Takahashi, N; Arutyunov, K; Pekola, JP; Aysto, J
A new approach to convert a high energy beam to a low energy one, which is essential for the next generation radioactive ion beam facilities, has been proposed and tested at Jyvaskyla, Finland. An open Ra-223 alpha-decay-recoil source has been used to produce radioactive ions in superfluid helium.
Dynamics of vortex assisted metal condensation in superfluid helium.
Popov, Evgeny; Mammetkuliyev, Muhammet; Eloranta, Jussi
2013-05-28
Laser ablation of copper and silver targets immersed in bulk normal and superfluid (4)He was studied through time-resolved shadowgraph photography. In normal fluid, only a sub-millimeter cavitation bubble is created and immediate formation of metal clusters is observed within a few hundred microseconds. The metal clusters remain spatially tightly focused up to 15 ms, and it is proposed that this observation may find applications in particle image velocimetry. In superfluid helium, the cavitation bubble formation process is distinctly different from the normal fluid. Due to the high thermal conductivity and an apparent lag in the breakdown of superfluidity, about 20% of the laser pulse energy was transferred directly into the liquid and a large gas bubble, up to several millimeters depending on laser pulse energy, is created. The internal temperature of the gas bubble is estimated to exceed 9 K and the following bubble cool down period therefore includes two separate phase transitions: gas-normal liquid and normal liquid-superfluid. The last stage of the cool down process was assigned to the superfluid lambda transition where a sudden formation of large metal clusters is observed. This is attributed to high vorticity created in the volume where the gas bubble previously resided. As shown by theoretical bosonic density functional theory calculations, quantized vortices can trap atoms and dimers efficiently, exhibiting static binding energies up to 22 K. This, combined with hydrodynamic Bernoulli attraction, yields total binding energies as high as 35 K. For larger clusters, the static binding energy increases as a function of the volume occupied in the liquid to minimize the surface tension energy. For heliophobic species an energy barrier develops as a function of the cluster size, whereas heliophilics show barrierless entry into vortices. The present theoretical and experimental observations are used to rationalize the previously reported metal nanowire assembly in
Functional renormalization group study of fluctuation effects in fermionic superfluids
Energy Technology Data Exchange (ETDEWEB)
Eberlein, Andreas
2013-03-22
This thesis is concerned with ground state properties of two-dimensional fermionic superfluids. In such systems, fluctuation effects are particularly strong and lead for example to a renormalization of the order parameter and to infrared singularities. In the first part of this thesis, the fermionic two-particle vertex is analysed and the fermionic renormalization group is used to derive flow equations for a decomposition of the vertex in charge, magnetic and pairing channels. In the second part, the channel-decomposition scheme is applied to various model systems. In the superfluid state, the fermionic two-particle vertex develops rich and singular dependences on momentum and frequency. After simplifying its structure by exploiting symmetries, a parametrization of the vertex in terms of boson-exchange interactions in the particle-hole and particle-particle channels is formulated, which provides an efficient description of the singular momentum and frequency dependences. Based on this decomposition of the vertex, flow equations for the effective interactions are derived on one- and two-loop level, extending existing channel-decomposition schemes to (i) the description of symmetry breaking in the Cooper channel and (ii) the inclusion of those two-loop renormalization contributions to the vertex that are neglected in the Katanin scheme. In the second part, the superfluid ground state of various model systems is studied using the channel-decomposition scheme for the vertex and the flow equations. A reduced model with interactions in the pairing and forward scattering channels is solved exactly, yielding insights into the singularity structure of the vertex. For the attractive Hubbard model at weak coupling, the momentum and frequency dependence of the two-particle vertex and the frequency dependence of the self-energy are determined on one- and two-loop level. Results for the suppression of the superfluid gap by fluctuations are in good agreement with the literature
On the mechanism of electromagnetic microwave absorption in superfluid helium
International Nuclear Information System (INIS)
Pashitskii, E. A.; Pentegov, V. I.
2012-01-01
In experiments on electromagnetic (EM) wave absorption in the microwave range in superfluid (SF) helium [1–3], a narrow EM field absorption line with a width on the order of (20–200) kHz was observed against the background of a wide absorption band with a width of 30–40 GHz at frequencies f 0 ≈ 110–180 GHz corresponding to the roton gap energy Δ r (T) in the temperature range 1.4–2.2 K. Using the so-called flexoelectric mechanism of polarization of helium atoms ( 4 He) in the presence of density gradients in SF helium (HeII), we show that nonresonance microwave absorption in the frequency range 170–200 GHz can be due to the existence of time-varying local density gradients produced by roton excitations in the bulk HeII. The absorption bandwidth is determined by the roton-roton scattering time in an equilibrium Boltzmann gas of rotons, which is t r-r ≈ 3.4 × 10 −11 s at T = 1.4 K and decreases upon heating. We propose that the anomalously narrow microwave resonance absorption line in HeII at the roton frequency f 0 (T) = Δr(T)/2πħ appears due to the following two factors: (i) the discrete structure of the spectrum of the surface EM resonator modes in the form of a periodic sequence of narrow peaks and (ii) the presence of a stationary dipole layer in HeII near the resonator surface, which forms due to polarization of 4 He atoms under the action of the density gradient associated with the vanishing of the density of the SF component at the solid wall. For this reason, the relaxation of nonequilibrium rotons generated in such a surface dipole layer is strongly suppressed, and the shape and width of the microwave resonance absorption line are determined by the roton density of states, which has a sharp peak at the edge of the roton gap in the case of weak dissipation. The effective dipole moments of rotons in the dipole layer can be directed either along or across the normal to the resonator surface, which explains the experimentally observed
Prediction of a Mobile Solid State in Dense Hydrogen under High Pressures.
Geng, Hua Y; Wu, Q; Sun, Y
2017-01-05
Solid rigidity and liquid-scale mobility are thought to be incompatible in elemental substances. One cannot have an elemental solid that is long-range positionally ordered wherein the atoms flow like in a liquid simultaneously. The only exception might be the hypothetical supersolid state of 4 He. In this work, we demonstrate that such exotic state could exist even in the classical regime. Using ab initio molecular dynamics (AIMD) and ab initio path integral molecular dynamics (AI-PIMD), a novel state of dense hydrogen that simultaneously has both long-range spatial ordering and liquid-scale atomic mobility is discovered at 1 to 1.5 TPa (1 TPa ≈ 10 000 000 atmospheric pressures). The features distinct from a normal solid and liquid are carefully characterized, and the stability and melting behavior are investigated. Extensive AI-PIMD simulations further revealed that this state might be (meta-)stable even at ultralow temperatures, suggesting an emerging candidate for an alternative type of supersolid state in dense metallic hydrogen.
Characterization of quantum vortex dynamics in superfluid helium
Meichle, David P.
Liquid helium obtains superfluid properties when cooled below the Lambda transition temperature of 2.17 K. A superfluid, which is a partial Bose Einstein condensate, has many exotic properties including free flow without friction, and ballistic instead of diffusive heat transport. A superfluid is also uniquely characterized by the presence of quantized vortices, dynamical line-like topological phase defects around which all circulation in the flow is constrained. Two vortices can undergo a violent process called reconnection when they approach, cross, and retract having exchanged tails. With a numerical examination of a local, linearized solution near reconnection we discovered a dynamically unstable stationary solution to the Gross-Pitaevskii equation, which was relaxed to a fully non-linear solution using imaginary time propagation. This investigation explored vortex reconnection in the context of the changing topology of the order parameter, a complex field governing the superfluid dynamics at zero temperature. The dynamics of the vortices can be studied experimentally by dispersing tracer particles into a superfluid flow and recording their motions with movie cameras. The pioneering work of Bewley et al. provided the first visualization technique using frozen gases to create tracer particles. Using this technique, we experimentally observed for the first time the excitation of helical traveling waves on a vortex core called Kelvin waves. Kelvin waves are thought to be a central mechanism for dissipation in this inviscid fluid, as they provide an efficient cascade mechanism for transferring energy from large to microscopic length scales. We examined the Kelvin waves in detail, and compared their dynamics in fully self-similar non-dimensional coordinates to theoretical predictions. Additionally, two experimental advances are presented. A newly invented technique for reliably dispersing robust, nanometer-scale fluorescent tracer particles directly into the
Dynamics of Superfluid Helium in Low-Gravity
Frank, David J.
1997-01-01
This report summarizes the work performed under a contract entitled 'Dynamics of Superfluid Helium in Low Gravity'. This project performed verification tests, over a wide range of accelerations of two Computational Fluid Dynamics (CFD) codes of which one incorporates the two-fluid model of superfluid helium (SFHe). Helium was first liquefied in 1908 and not until the 1930s were the properties of helium below 2.2 K observed sufficiently to realize that it did not obey the ordinary physical laws of physics as applied to ordinary liquids. The term superfluidity became associated with these unique observations. The low temperature of SFHe and it's temperature unifonrmity have made it a significant cryogenic coolant for use in space applications in astronomical observations with infrared sensors and in low temperature physics. Superfluid helium has been used in instruments such as the Shuttle Infrared Astronomy Telescope (IRT), the Infrared Astronomy Satellite (IRAS), the Cosmic Background Observatory (COBE), and the Infrared Satellite Observatory (ISO). It is also used in the Space Infrared Telescope (SIRTF), Relativity Mission Satellite formally called Gravity Probe-B (GP-B), and the Test of the Equivalence Principle (STEP) presently under development. For GP-B and STEP, the use of SFHE is used to cool Superconducting Quantum Interference Detectors (SQUIDS) among other parts of the instruments. The Superfluid Helium On-Orbit Transfer (SHOOT) experiment flown in the Shuttle studied the behavior of SFHE. This experiment attempted to get low-gravity slosh data, however, the main emphasis was to study the low-gravity transfer of SFHE from tank to tank. These instruments carried tanks of SFHE of a few hundred liters to 2500 liters. The capability of modeling the behavior of SFHE is important to spacecraft control engineers who must design systems that can overcome disturbances created by the movement of the fluid. In addition instruments such as GP-B and STEP are very
Transitions and excitations in a superfluid stream passing small impurities
Pinsker, Florian
2014-05-08
We analyze asymptotically and numerically the motion around a single impurity and a network of impurities inserted in a two-dimensional superfluid. The criticality for the breakdown of superfluidity is shown to occur when it becomes energetically favorable to create a doublet—the limiting case between a vortex pair and a rarefaction pulse on the surface of the impurity. Depending on the characteristics of the potential representing the impurity, different excitation scenarios are shown to exist for a single impurity as well as for a lattice of impurities. Depending on the lattice characteristics it is shown that several regimes are possible: dissipationless flow, excitations emitted by the lattice boundary, excitations created in the bulk, and the formation of large-scale structures.
Superfluid/Bose-glass transition in one dimension
Ristivojevic, Zoran; Petković, Aleksandra; Le Doussal, Pierre; Giamarchi, Thierry
2014-09-01
We consider a one-dimensional system of interacting bosons in a random potential. At zero temperature, it can be either in the superfluid or in the insulating phase. We study the transition at weak disorder and moderate interaction. Using a systematic approach, we derive the renormalization group equations at two-loop order and discuss the phase diagram. We find the universal form of the correlation functions at the transitions and compute the logarithmic corrections to the main universal power-law behavior. In order to mimic large density fluctuations on a single site, we study a simplified model of disordered two-leg bosonic ladders with correlated disorder across the rung. Contrarily to the single-chain case, the latter system exhibits a transition between a superfluid and a localized phase where the exponents of the correlation functions at the transition do not take universal values.
Turbulent statistics and intermittency enhancement in coflowing superfluid 4He
Biferale, L.; Khomenko, D.; L'vov, V.; Pomyalov, A.; Procaccia, I.; Sahoo, G.
2018-02-01
The large-scale turbulent statistics of mechanically driven superfluid 4He was shown experimentally to follow the classical counterpart. In this paper, we use direct numerical simulations to study the whole range of scales in a range of temperatures T ∈[1.3 ,2.1 ] K. The numerics employ self-consistent and nonlinearly coupled normal and superfluid components. The main results are that (i) the velocity fluctuations of normal and super components are well correlated in the inertial range of scales, but decorrelate at small scales. (ii) The energy transfer by mutual friction between components is particulary efficient in the temperature range between 1.8 and 2 K, leading to enhancement of small-scale intermittency for these temperatures. (iii) At low T and close to Tλ, the scaling properties of the energy spectra and structure functions of the two components are approaching those of classical hydrodynamic turbulence.
Lifshitz effects on holographic p-wave superfluid
Directory of Open Access Journals (Sweden)
Ya-Bo Wu
2015-02-01
Full Text Available In the probe limit, we numerically build a holographic p-wave superfluid model in the four-dimensional Lifshitz black hole coupled to a Maxwell-complex vector field. We observe the rich phase structure and find that the Lifshitz dynamical exponent z contributes evidently to the effective mass of the matter field and dimension of the gravitational background. Concretely, we obtain that the Cave of Winds appeared only in the five-dimensional anti-de Sitter (AdS spacetime, and the increasing z hinders not only the condensate but also the appearance of the first-order phase transition. Furthermore, our results agree with the Ginzburg–Landau results near the critical temperature. In addition, the previous AdS superfluid model is generalized to the Lifshitz spacetime.
Destruction of superfluidity by disorder in one dimension
International Nuclear Information System (INIS)
Zhang, L.; Ma, M.
1988-01-01
We study the effect of disorder on the superfluidity of the hard-sphere Bose gas in one dimension. This system is equivalent to the spin-(1/2 XY model with a random transverse field, which in turn can be mapped onto a disordered spinless-fermion model. We show that the localization of all fermionic states implies an exponential decay in the spin-spin correlation function and hence the instability of the superfluid against any amount of disorder. We point out a fundamental difference in the characteristics of the Jordan-Wigner transformation between the pure and disordered systems. Generalization of our results beyond the present model and implications to disordered superconductivity are discussed
Three Dimensional Quantized Vortex Dynamics in Superfluid Helium
Meichle, David; Megson, Peter; Lathrop, Daniel
2014-11-01
Vorticity is constrained to line-like topological defects in quantum superfluids, such as liquid Helium below the Lambda transition temperature of 2.17 Kelvin. A tangle of vortices exists in a dissipative dynamical state called quantum turbulence, which has quantitative features distinct from classical turbulence. To study the vortex dynamics, we have invented a novel method to disperse fluorescent nanoparticles directly into the superfluid which become trapped on the vortex cores. Using a newly constructed multi-camera stereographic microscope, we present new data showing vortex reconnections and Kelvin waves with fully three-dimensional particle trajectories. These events are of scientific interest as they play a key role in the dissipation of quantum turbulence.
Inelastic scattering of xenon atoms by quantized vortices in superfluids
Pshenichnyuk, I. A.; Berloff, N. G.
2016-11-01
We study inelastic interactions of particles with quantized vortices in superfluids by using a semiclassical matter wave theory that is analogous to the Landau two-fluid equations, but allows for the vortex dynamics. The research is motivated by recent experiments on xenon-doped helium nanodroplets that show clustering of the impurities along the vortex cores. We numerically simulate the dynamics of trapping and interactions of xenon atoms by quantized vortices in superfluid helium and the obtained results can be extended to scattering of other impurities by quantized vortices. Different energies and impact parameters of incident particles are considered. We show that inelastic scattering is closely linked to the generation of Kelvin waves along a quantized vortex during the interaction even if there is no capture. The capture criterion of an impurity is formulated in terms of the binding energy.
Superfluid Turbulence from Quantum Kelvin Wave to Classical Kolmogorov Cascades
International Nuclear Information System (INIS)
Yepez, Jeffrey; Vahala, George; Vahala, Linda; Soe, Min
2009-01-01
The main topological feature of a superfluid is a quantum vortex with an identifiable inner and outer radius. A novel unitary quantum lattice gas algorithm is used to simulate quantum turbulence of a Bose-Einstein condensate superfluid described by the Gross-Pitaevskii equation on grids up to 5760 3 . For the first time, an accurate power-law scaling for the quantum Kelvin wave cascade is determined: k -3 . The incompressible kinetic energy spectrum exhibits very distinct power-law spectra in 3 ranges of k space: a classical Kolmogorov k -(5/3) spectrum at scales greater than the outer radius of individual quantum vortex cores and a quantum Kelvin wave cascade spectrum k -3 on scales smaller than the inner radius of the quantum vortex core. The k -3 quantum Kelvin wave spectrum due to phonon radiation is robust, while the k -(5/3) classical Kolmogorov spectrum becomes robust on large grids.
Novel Role of Superfluidity in Low-Energy Nuclear Reactions.
Magierski, Piotr; Sekizawa, Kazuyuki; Wlazłowski, Gabriel
2017-07-28
We demonstrate, within symmetry unrestricted time-dependent density functional theory, the existence of new effects in low-energy nuclear reactions which originate from superfluidity. The dynamics of the pairing field induces solitonic excitations in the colliding nuclear systems, leading to qualitative changes in the reaction dynamics. The solitonic excitation prevents collective energy dissipation and effectively suppresses the fusion cross section. We demonstrate how the variations of the total kinetic energy of the fragments can be traced back to the energy stored in the superfluid junction of colliding nuclei. Both contact time and scattering angle in noncentral collisions are significantly affected. The modification of the fusion cross section and possibilities for its experimental detection are discussed.
Chiral symmetry breaking in superfluid 3He-A.
Ikegami, H; Tsutsumi, Y; Kono, K
2013-07-05
Spontaneous symmetry breaking is an important concept in many branches of physics. In helium-3 ((3)He), the breaking of symmetry leads to the orbital chirality in the superfluid phase known as (3)He-A. Chirality is a fundamental property of (3)He-A, but its direct detection has been challenging. We report direct detection of chirality by transport measurements of electrons trapped below a free surface of (3)He-A. In particular, we observed the so-called intrinsic Magnus force experienced by a moving electron; the direction of the force directly reflected the chirality. We further showed that, at the superfluid transition, the system selected either right- or left-handed chirality. The observation of such selection directly demonstrates chiral symmetry breaking.
Physical acoustics at UCLA in the study of superfluid helium
International Nuclear Information System (INIS)
Rudnick, I.
1976-01-01
The theory of sound propagation in superfluid helium is reviewed. The theory of first, second, fourth and third sound is considered. A simple approximate derivation of the velocity of third sound is given and the Doppler shift of first, second, third and fourth sound is discussed. Experimental aspects of first, second, third and fourth sound are considered in turn. For first sound consideration is given to first-sound transducers, cavitation in liquid helium and velocity at the lambda transition. Second-sound transducers and the velocity of second sound at the lambda transition are discussed. Experimental aspects of third-sound transducers, the velocity and attenuation of third sound, the critical velocity of superfluid films and the thickness of a moving film are then discussed. Various aspects of fourth sound are considered. (B.R.H.)
Metastable Helium Molecules as Tracers in Superfluid 4He
International Nuclear Information System (INIS)
Guo, W.; Wright, J. D.; Cahn, S. B.; Nikkel, J. A.; McKinsey, D. N.
2009-01-01
Metastable helium molecules generated in a discharge near a sharp tungsten tip immersed in superfluid 4 He are imaged using a laser-induced-fluorescence technique. By pulsing the tip, a small cloud of He 2 * molecules is produced. We can determine the normal-fluid velocity in a heat-induced counterflow by tracing the position of a single molecule cloud. As we run the tip in continuous field-emission mode, a normal-fluid jet from the tip is generated and molecules are entrained in the jet. A focused 910 nm pump laser pulse is used to drive a small group of molecules to the first excited vibrational level of the triplet ground state. Subsequent imaging of the tagged molecules with an expanded 925 nm probe laser pulse allows us to measure the flow velocity of the jet. The techniques we developed provide new tools in quantitatively studying the normal fluid flow in superfluid helium.
px+ipy Superfluid from s-Wave Interactions of Fermionic Cold Atoms
International Nuclear Information System (INIS)
Zhang Chuanwei; Tewari, Sumanta; Lutchyn, Roman M.; Das Sarma, S.
2008-01-01
Two-dimensional (p x +ip y ) superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p x +ip y superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave superfluid
Nodal Topological Phases in s-wave Superfluid of Ultracold Fermionic Gases
Huang, Bei-Bing; Yang, Xiao-Sen
2018-02-01
The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected nodal lines, which can be regarded as the superfluid counterpart of nodal line semimetal in the condensed matter physics, just as Weyl superfluid with Weyl semimetal. In this paper we study the ground states of the cold fermionic gases in cubic optical lattices with one-dimensional spin-orbit coupling and transverse Zeeman field and map out the topological phase diagram of the system. We demonstrate that in addition to a fully gapped topologically trivial phase, some different nodal line superfluid phases appear when the Zeeman field is adjusted. The presence of topologically stable nodal lines implies the dispersionless zero-energy flat band in a finite region of the surface Brillouin zone. Experimentally these nodal line superfluid states can be detected via the momentum-resolved radio-frequency spectroscopy. The nodal line topological superfluid provide fertile grounds for exploring exotic quantum matters in the context of ultracold atoms. Supported by National Natural Science Foundation of China under Grant Nos. 11547047 and 11504143
Transverse force on a vortex in lattice models of superfluids
Sonin, E. B.
2013-01-01
The paper derives the transverse forces (the Magnus and the Lorentz forces) in the lattice models of superfluids in the continuous approximation. The continuous approximation restores translational invariance absent in the original lattice model, but the theory is not Galilean invariant. As a result, calculation of the two transverse forces on the vortex, Magnus force and Lorentz force, requires the analysis of two balances, for the true momentum of particles in the lattice (Magnus force) and...
Probing the A-B interface of superfluid helium-3
Haley, Richard
2015-03-01
At temperatures around 1 mK helium-3 forms a BCS spin triplet condensate. The order parameter is sufficiently complex that more than one superfluid phase exists, each exhibiting a different broken symmetry, and there is a model first order transition between the two most stable phases, labeled A and B. The Lancaster Ultra-Low Temperature Group has developed techniques to probe the properties of the A-B interface in the deep sub-mK regime where the superfluid is in the pure condensate limit. Shaped and controllable magnetic fields are used to induce the transition, and to stabilize and move the A-B phase boundary inside the experimental volume. The latent heat of the transition has been measured, and the nucleation behavior shown to be incompatible with conventional thermodynamic models. Since superfluid helium-3 is inherently pure, and the order parameter transforms continuously across the A-B interface, it is the most coherent two-dimensional structure to which we have experimental access. It has been proposed that this 2D surface in the surrounding 3D bulk volume is a good analog of a cosmological brane separating two distinct quantum vacuum states; experiments that simulate brane annihilation and the creation of topological defects have been carried out at Lancaster. Other investigations have included measurements of the surface tension and wetting behavior of the interface. During these studies it was discovered that a large, unpredicted frictional force was acting on the interface even though it is moving through a pure superfluid. Recent breakthrough work on the dynamics of the A-B interface has finally solved this puzzle. Current experiments include a setup where the interface region is probed directly using quartz tuning fork resonators that couple to the local density of broken Cooper pair quasiparticle excitations and thus give insight into the order parameter energy gap structure as A transforms to B.
Stability criterion for superfluidity based on the density spectral function
Watabe, Shohei; Kato, Yusuke
2013-12-01
We study a stability criterion hypothesis for superfluids expressed in terms of the local density spectral function In(r,ω) that is applicable to both homogeneous and inhomogeneous systems. We evaluate the local density spectral function in the presence of a one-dimensional repulsive or attractive external potential within Bogoliubov theory, using solutions for the tunneling problem. We also evaluate the local density spectral function using an orthogonal basis, and calculate the autocorrelation function Cn(r,t). When superfluids in a d-dimensional system flow below a threshold, In(r,ω)∝ωd holds in the low-energy regime and Cn(r,t)∝1/td+1 holds in the long-time regime. However, when superfluids flow with the critical current, In(r,ω)∝ωβ holds in the low-energy regime and Cn(r,t)∝1/tβ+1 holds in the long-time regime with β
Transverse forces on vortices in superfluids in a periodic potential
Sonin, E. B.
2016-08-01
The paper analyzes the transverse forces (the Magnus and the Lorentz forces) on vortices in superfluids put into periodic potentials at T =0 . The case of weak potential and the tight-binding limit described by the Bose-Hubbard model were addressed. The analysis was based on the balance of true momentum and quasimomentum. A special attention was paid to the superfluid close to the superfluid-insulator transition. In this area of the phase diagram the theory predicts the particle-hole symmetry line where the Magnus force changes sign with respect to that expected from the sign of velocity circulation. Our analysis has shown that the magnitude of the Magnus force is a continuous function at crossing the particle-hole symmetry line. This challenges the theory connecting the magnitude of the Magnus force with topological Chern numbers and predicting a jump at crossing this line. Disagreement is explained by the role of intrinsic pinning and guided vortex motion ignored in the topological approach. It is one more evidence that in general topological arguments are not sufficient for derivation of equations of vortex motion.
Transient behavior of superfluid turbulence in a large channel
International Nuclear Information System (INIS)
Schwarz, K.W.; Rozen, J.R.
1991-01-01
The transient behavior of superfluid turbulence is studied theoretically and experimentally with the aim of understanding the disagreement between vortex-tangle theory and past measurements of free vortex-tangle decay in superfluid 4 He. Scaling theory is extended and large-scale simulations based on the reconnecting-vortex model are carried out. These imply that the Vinen equation should be a reasonable approximation even for rather large transients, and predict definite values for the Vinen parameters. Direct measurements of the vortex-tangle response to a sudden change in the driving velocity are seen to be in reasonable agreement with these predictions. It is found, however, that when the vortex tangle is allowed to decay farther toward zero, it eventually crosses over into a state of anomalously slow decay, which appears to be that observed in previous experiments. We argue that this regime should be interpreted in terms of a coupled-turbulence state in which random superfluid and normal-fluid motion interacts with the vortex tangle, the whole system decaying self-consistently at a rate controlled by the normal-fluid viscosity. Several additional qualitative observations which may be relevant to the question of how the vortex tangle is initiated are also reported
Ketterson, John B
2016-01-01
This comprehensive text covers the basic physics of the solid state starting at an elementary level suitable for undergraduates but then advancing, in stages, to a graduate and advanced graduate level. In addition to treating the fundamental elastic, electrical, thermal, magnetic, structural, electronic, transport, optical, mechanical and compositional properties, we also discuss topics like superfluidity and superconductivity along with special topics such as strongly correlated systems, high-temperature superconductors, the quantum Hall effects, and graphene. Particular emphasis is given to so-called first principles calculations utilizing modern density functional theory which for many systems now allow accurate calculations of the electronic, magnetic, and thermal properties.
Bose-Einstein condensation and superfluidity of dipolar excitons in a phosphorene double layer
Berman, Oleg L.; Gumbs, Godfrey; Kezerashvili, Roman Ya.
2017-07-01
We study the formation of dipolar excitons and their superfluidity in a phosphorene double layer. The analytical expressions for the single dipolar exciton energy spectrum and wave function are obtained. It is predicted that a weakly interacting gas of dipolar excitons in a double layer of black phosphorus exhibits superfluidity due to the dipole-dipole repulsion between the dipolar excitons. In calculations are employed the Keldysh and Coulomb potentials for the interaction between the charge carriers to analyze the influence of the screening effects on the studied phenomena. It is shown that the critical velocity of superfluidity, the spectrum of collective excitations, concentrations of the superfluid and normal component, and mean-field critical temperature for superfluidity are anisotropic and demonstrate the dependence on the direction of motion of dipolar excitons. The critical temperature for superfluidity increases if the exciton concentration and the interlayer separation increase. It is shown that the dipolar exciton binding energy and mean-field critical temperature for superfluidity are sensitive to the electron and hole effective masses. The proposed experiment to observe a directional superfluidity of excitons is addressed.
Absorption of electromagnetic field energy by superfluid system of atoms with electric dipole moment
International Nuclear Information System (INIS)
Poluektov, Yu.M.
2014-01-01
The modified Gross-Pitaevskii equation which takes into account relaxation and interaction with alternating electromagnetic field is used to consider the absorption of electromagnetic field energy by a superfluid system on the assumption that the atoms has intrinsic dipole moment. It is shown that the absorption may be of a resonant behavior only if the dispersion curves of the electromagnetic wave and the excitations of the superfluid system intersect. It is remarkable that such a situation is possible if the superfluid system has a branch of excitations with the energy gap at low momenta. The experiments on absorption of microwaves in superfluid helium are interpreted as evidence of existence of such gap excitations. A possible modification of the excitation spectrum of superfluid helium in the presence of excitation branch with energy gap is dis-cussed qualitatively
Coupled dipole oscillations of a mass-imbalanced Bose-Fermi superfluid mixture
Wu, Yu-Ping; Yao, Xing-Can; Liu, Xiang-Pei; Wang, Xiao-Qiong; Wang, Yu-Xuan; Chen, Hao-Ze; Deng, Youjin; Chen, Yu-Ao; Pan, Jian-Wei
2018-01-01
Recent experimental realizations of superfluid mixtures of Bose and Fermi quantum gases provide a unique platform for exploring diverse superfluid phenomena. We study dipole oscillations of a double superfluid in a cigar-shaped optical dipole trap, consisting of 41K and 6Li atoms with a large mass imbalance, where the oscillations of the bosonic and fermionic components are coupled via the Bose-Fermi interaction. In our high-precision measurements, the frequencies of both components are observed to be shifted from the single-species ones, and exhibit unusual features. The frequency shifts of the 41K component are upward (downward) in the radial (axial) direction, whereas the 6Li component has downshifted frequencies in both directions. Most strikingly, as the interaction strength is varied, the frequency shifts display a resonantlike behavior in both directions, for both species, and around a similar location at the BCS side of the fermionic superfluid. These rich phenomena challenge the theoretical understanding of superfluids.
Domain-area distribution anomaly in segregating multicomponent superfluids
Takeuchi, Hiromitsu
2018-01-01
The domain-area distribution in the phase transition dynamics of Z2 symmetry breaking is studied theoretically and numerically for segregating binary Bose-Einstein condensates in quasi-two-dimensional systems. Due to the dynamic-scaling law of the phase ordering kinetics, the domain-area distribution is described by a universal function of the domain area, rescaled by the mean distance between domain walls. The scaling theory for general coarsening dynamics in two dimensions hypothesizes that the distribution during the coarsening dynamics has a hierarchy with the two scaling regimes, the microscopic and macroscopic regimes with distinct power-law exponents. The power law in the macroscopic regime, where the domain size is larger than the mean distance, is universally represented with the Fisher's exponent of the percolation theory in two dimensions. On the other hand, the power-law exponent in the microscopic regime is sensitive to the microscopic dynamics of the system. This conjecture is confirmed by large-scale numerical simulations of the coupled Gross-Pitaevskii equation for binary condensates. In the numerical experiments of the superfluid system, the exponent in the microscopic regime anomalously reaches to its theoretical upper limit of the general scaling theory. The anomaly comes from the quantum-fluid effect in the presence of circular vortex sheets, described by the hydrodynamic approximation neglecting the fluid compressibility. It is also found that the distribution of superfluid circulation along vortex sheets obeys a dynamic-scaling law with different power-law exponents in the two regimes. An analogy to quantum turbulence on the hierarchy of vorticity distribution and the applicability to chiral superfluid 3He in a slab are also discussed.
Motion of ions in normal and superfluid 3He
International Nuclear Information System (INIS)
Fetter, A.L.; Kurkijaervi, J.; Helsinki Univ. of Technology, Otaniemi
1976-11-01
The drag force on an ion in low-temperature 3 He is studied with a generalization of the Josephson-Lekner formalism, keeping higher-order terms in the velocity and coherence factors in the superfluid phase. In the normal state, a diffusive model for inelastic-scattering corrections provides an estimate of the onset velocity for nonlinearity in the drag force. Analytic calculations in 3 He-B for elastic scattering at low and high velocity (v Δ/psub(F)) agree qualitatively with the experimental observations near Tsub(c). (author)
Solitons, Bose-Einstein condensation and superfluidity in He II
International Nuclear Information System (INIS)
Chela-Flores, J.; Ghassib, H.B.
1985-09-01
The analytic form of a wave propagating with a constant velocity and a permanent profile is inferred for a weakly interacting Bose gas, using an exact (rather than asymptotic) solution of the field equation of the self-consistent Hartree model. The significance of this approach is indicated, especially when realistic interatomic potentials are used. In addition, the general relation between solitons and Bose-Einstein condensation is underlined by invoking the profound insight recently acquired in studies of the quantum liquids involved in the living state. It is concluded that solitons may occur in He II, and may play a significant role in the phenomena of superfluidity. (author)
Detectability of Light Dark Matter with Superfluid Helium.
Schutz, Katelin; Zurek, Kathryn M
2016-09-16
We show that a two-excitation process in superfluid helium, combined with sensitivity to meV energy depositions, can probe dark matter down to the ∼keV warm dark matter mass limit. This mass reach is 3 orders of magnitude below what can be probed with ordinary nuclear recoils in helium at the same energy resolution. For dark matter lighter than ∼100 keV, the kinematics of the process requires the two athermal excitations to have nearly equal and opposite momentum, potentially providing a built-in coincidence mechanism for controlling backgrounds.
Possible circuits for superconducting coil cooling by superfluid helium
International Nuclear Information System (INIS)
Shaposhnikov, V.A.; Volkova, N.M.
1984-01-01
Investigation results on heat transfer in heated channels under conditions of internal and forced He-2 convection are presented in order to obtain estimated dependences allowing to design cryostatting system for superconducting magnetic systems (SMS). Different cryostatting schemes are considered, and results of their calculations are presented. It is shown that in cryostatting system designing it is necessary to prefer the scheme, in which heat exchager is put into a bath with superfluid helium. One cryostatting scheme is presented; cooling of the heat release object in it is performed under conditions of forced motion. It is sown that the process of forced convection enlarges the heat exchange efficiency
Experiments on second-sound shock waves in superfluid helium
International Nuclear Information System (INIS)
Cummings, J.C.; Schmidt, D.W.; Wagner, W.J.
1978-01-01
The waveform and velocity of second-sound waves in superfluid helium have been studied experimentally using superconducting, thin-film probes. The second-sound waves were generated with electrical pulses through a resistive film. Variations in pulse power, pulse duration, and bath temperature were examined. As predicted theoretically, the formation of a shock was observed at the leading or trailing edge of the waves depending on bath temperature. Breakdown of the theoretical model was observed for large pulse powers. Accurate data for the acoustic second-sound speed were derived from the measurements of shock-wave velocities and are compared with previous results
Population imbalanced fermionic superfluids. From cold atoms to QCD
International Nuclear Information System (INIS)
Forbes, Michael McNeil
2008-01-01
A simple microscopic model for resonant cold, two-component Fermi superfluids is presented that is directly realized in cold atom systems and provides a good approximation to neutron matter. Extremely simple and tightly constrained by thermodynamics and scaling analyses, this model exhibits a diverse phase structure comprising population imbalanced phases, and should be treated as a benchmark for validating many-body theories that attempt to describe more complex systems such as high-density QCD. I shall discuss our present state of knowledge about this model, and how it might be used to help understand QCD. (author)
Is a Doubly Quantized Vortex Dynamically Unstable in Uniform Superfluids?
Takeuchi, Hiromitsu; Kobayashi, Michikazu; Kasamatsu, Kenichi
2018-02-01
We revisit the fundamental problem of the splitting instability of a doubly quantized vortex in uniform single-component superfluids at zero temperature. We analyze the system-size dependence of the excitation frequency of a doubly quantized vortex through large-scale simulations of the Bogoliubov-de Gennes equation, and find that the system remains dynamically unstable even in the infinite-system-size limit. Perturbation and semi-classical theories reveal that the splitting instability radiates a damped oscillatory phonon as an opposite counterpart of a quasi-normal mode.
Incompressible flows of superfluid films on multiply-connected surfaces
International Nuclear Information System (INIS)
Corrada-Emmanuel, A.
1989-01-01
The theory of Riemann surfaces is applied to the problem of constructing quantized vortex flows in closed surfaces of arbitrary but finite genus. An in principle procedure for obtaining the lowest energy flow is presented. It is shown that quantized vortices in non-zero genus surfaces are, in general, not isomorphic to a Coulomb gas. This failure has a geometrical origin: the appearance in non-zero genus surfaces of closed curves that are not the boundary of any area. A theorem of Riemann is applied to the genus one surface, the torus, to show quantitatively how to construct the quantized vortices. Because of the breakdown in the isomorphism between quantized vortices and charges, a novel effect is possible: the violation of Earnshaw's theorem. On a torus a single vortex can be placed in local stable equilibrium. The uniform flows around the holes of the torus also lead to a new result: a non-vortex mechanism for the destruction of superfluidity in the film. An explicit formula is derived showing this effect by considering the response of a helium film to a rotation of the torus. The author predicts that torii of dissimilar proportions will exhibit different superfluid densities at the same temperature
Gravitational wave as probe of superfluid dark matter
Cai, Rong-Gen; Liu, Tong-Bo; Wang, Shao-Jiang
2018-02-01
In recent years, superfluid dark matter (SfDM) has become a competitive model of emergent modified Newtonian dynamics (MOND) scenario: MOND phenomenons naturally emerge as a derived concept due to an extra force mediated between baryons by phonons as a result of axionlike particles condensed as superfluid at galactic scales; Beyond galactic scales, these axionlike particles behave as normal fluid without phonon-mediated MOND-like force between baryons, therefore SfDM also maintains the usual success of Λ CDM at cosmological scales. In this paper, we use gravitational waves (GWs) to probe the relevant parameter space of SfDM. GWs through Bose-Einstein condensate (BEC) could propagate with a speed slightly deviation from the speed-of-light due to the change in the effective refractive index, which depends on the SfDM parameters and GW-source properties. We find that Five hundred meter Aperture Spherical Telescope (FAST), Square Kilometre Array (SKA) and International Pulsar Timing Array (IPTA) are the most promising means as GW probe of relevant parameter space of SfDM. Future space-based GW detectors are also capable of probing SfDM if a multimessenger approach is adopted.
Rotovibrational spectroscopy of hydrogen peroxide embedded in superfluid helium nanodroplets.
Raston, Paul L; Knapp, Chrissy J; Jäger, Wolfgang
2011-11-14
We report the infrared depletion spectrum of para- and ortho-hydrogen peroxide embedded in superfluid helium nanodroplets in the OH stretching region. Six transitions were observed in the antisymmetric stretching band (v(5)) of H(2)O(2), and three in the weaker symmetric stretching band (v(1)). While rotations about the b- and c-axes are slowed by a factor of ∼0.4 relative to the gas phase, rotations about the a-axis are not significantly affected; this relates to the rotational speed about the a-axis being too fast for helium density to adiabatically follow. The trans tunneling splitting does not appear to be considerably affected by the helium droplet environment, and is reduced by only 6% relative to the gas phase, under the assumption that the vibrational shifts of the v(5) and v(1) torsional subbands are the same. The linewidths increase with increasing rotorsional energies, and are significantly narrower for energies which fall within the "phonon gap" of superfluid helium. These narrower lines are asymmetrically broadened, indicative of a dynamical coupling between the H(2)O(2) rotor and surrounding helium density.
Viscosity bound for anisotropic superfluids with dark matter sector
Rogatko, Marek; Wysokiński, Karol I.
2017-07-01
The shear viscosity to the entropy density ratio η /s of the anisotropic superfluid has been calculated by means of the gauge/gravity duality in the presence of the dark matter sector. The dark matter has been described by the Yang-Mills field analogous to the one describing the visible matter sector, and it is assumed to interact with the visible field with coupling constant α . Close to the superfluid transition temperature (Tc), the analytical solution has been given up to the leading order in a symmetry breaking parameter and the ratio of the gravitational constant and Yang-Mils coupling. The tensor element of ratio η /s remains unaffected by the dark matter for the viscosity tensor in the plane perpendicular to the symmetry breaking direction (here, y z ). The temperature dependence and the linear correction in (1 -α ) in the plane containing this direction (here, x y ) was also revealed. The correction linearly vanishes for temperature tending to the critical one T →Tc.
Two-component Superfluid Hydrodynamics of Neutron Star Cores
International Nuclear Information System (INIS)
Kobyakov, D. N.; Pethick, C. J.
2017-01-01
We consider the hydrodynamics of the outer core of a neutron star under conditions when both neutrons and protons are superfluid. Starting from the equation of motion for the phases of the wave functions of the condensates of neutron pairs and proton pairs, we derive the generalization of the Euler equation for a one-component fluid. These equations are supplemented by the conditions for conservation of neutron number and proton number. Of particular interest is the effect of entrainment, the fact that the current of one nucleon species depends on the momenta per nucleon of both condensates. We find that the nonlinear terms in the Euler-like equation contain contributions that have not always been taken into account in previous applications of superfluid hydrodynamics. We apply the formalism to determine the frequency of oscillations about a state with stationary condensates and states with a spatially uniform counterflow of neutrons and protons. The velocities of the coupled sound-like modes of neutrons and protons are calculated from properties of uniform neutron star matter evaluated on the basis of chiral effective field theory. We also derive the condition for the two-stream instability to occur.
Transverse forces on a vortex in lattice models of superfluids
Sonin, E. B.
2013-12-01
The paper derives the transverse forces (the Magnus and the Lorentz forces) in the lattice models of superfluids in the continuous approximation. The continuous approximation restores translational invariance absent in the original lattice model, but the theory is not Galilean invariant. As a result, calculation of the two transverse forces on the vortex, Magnus force and Lorentz force, requires the analysis of two balances, for the true momentum of particles in the lattice (Magnus force) and for the quasimomentum (Lorentz force) known from the Bloch theory of particles in the periodic potential. While the developed theory yields the same Lorentz force, which was well known before, a new general expression for the Magnus force was obtained. The theory demonstrates how a small Magnus force emerges in the Josephson-junction array if the particle-hole symmetry is broken. The continuous approximation for the Bose-Hubbard model close to the superfluid-insulator transition was developed, which was used for calculation of the Magnus force. The theory shows that there is an area in the phase diagram for the Bose-Hubbard model, where the Magnus force has an inverse sign with respect to that which is expected from the sign of velocity circulation.
Moving solitons in a one-dimensional fermionic superfluid
Efimkin, Dmitry K.; Galitski, Victor
2015-02-01
A fully analytical theory of a traveling soliton in a one-dimensional fermionic superfluid is developed within the framework of time-dependent self-consistent Bogoliubov-de Gennes equations, which are solved exactly in the Andreev approximation. The soliton manifests itself in a kinklike profile of the superconducting order parameter and hosts a pair of Andreev bound states in its core. They adjust to the soliton's motion and play an important role in its stabilization. A phase jump across the soliton and its energy decrease with the soliton's velocity and vanish at the critical velocity, corresponding to the Landau criterion, where the soliton starts emitting quasiparticles and becomes unstable. The "inertial" and "gravitational" masses of the soliton are calculated and the former is shown to be orders of magnitude larger than the latter. This results in a slow motion of the soliton in a harmonic trap, reminiscent of the observed behavior of a solitonlike texture in related experiments in cold fermion gases [T. Yefsah et al., Nature (London) 499, 426 (2013), 10.1038/nature12338]. Furthermore, we calculate the full nonlinear dispersion relation of the soliton and solve the classical equations of motion in a trap. The strong nonlinearity at high velocities gives rise to anharmonic oscillatory motion of the soliton. A careful analysis of this anharmonicity may provide a means to experimentally measure the nonlinear soliton spectrum in superfluids.
NASA'S Chandra Finds Superfluid in Neutron Star's Core
2011-02-01
NASA's Chandra X-ray Observatory has discovered the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the core of a neutron star. Superfluids created in laboratories on Earth exhibit remarkable properties, such as the ability to climb upward and escape airtight containers. The finding has important implications for understanding nuclear interactions in matter at the highest known densities. Neutron stars contain the densest known matter that is directly observable. One teaspoon of neutron star material weighs six billion tons. The pressure in the star's core is so high that most of the charged particles, electrons and protons, merge resulting in a star composed mostly of uncharged particles called neutrons. Two independent research teams studied the supernova remnant Cassiopeia A, or Cas A for short, the remains of a massive star 11,000 light years away that would have appeared to explode about 330 years ago as observed from Earth. Chandra data found a rapid decline in the temperature of the ultra-dense neutron star that remained after the supernova, showing that it had cooled by about four percent over a 10-year period. "This drop in temperature, although it sounds small, was really dramatic and surprising to see," said Dany Page of the National Autonomous University in Mexico, leader of a team with a paper published in the February 25, 2011 issue of the journal Physical Review Letters. "This means that something unusual is happening within this neutron star." Superfluids containing charged particles are also superconductors, meaning they act as perfect electrical conductors and never lose energy. The new results strongly suggest that the remaining protons in the star's core are in a superfluid state and, because they carry a charge, also form a superconductor. "The rapid cooling in Cas A's neutron star, seen with Chandra, is the first direct evidence that the cores of these neutron stars are, in fact, made of superfluid and
An Ultracold Neutron Source using Superfluid Helium at TRIUMF
Matsumiya, Ryohei; Kawasaki, Shinsuke; Canada-Japan UCN Collaboration Collaboration
2016-09-01
An Ultracold Neutrons (UCN) are an extremely slow neutrons with a kinetic energy in the order of 100 neV. As a consequence, UCNs are totally reflected at surface of certain materials and can be confined in a material bottle. Using this unique property, UCNs are used for various experiments such as neutron electric dipole moment searches, neutron lifetime measurements, gravity experiments, and other. A UCN source has been developed at the Research Center for Nuclear Physics (RCNP), in Osaka Japan. The UCN source is composed of a combination of a spallation neutron source and a superfluid helium UCN converter. Spallation neutrons are thermalized first by warm and cold D2O moderators. After that they give their kinetic energy to a phonon (single- phonon excitation) or phonons (multi-phonon excitation) in superfluid helium to result in UCNs. The UCN source achieved 26 UCN/cm3 at 1 μA proton current at RCNP. Now, the source is adapted to a new, dedicated proton beam line at TRIUMF for use at higher proton beam currents up to 40 μA. The developments at RCNP and future prospects at TRIUMF will be discussed.
Superconductivity and superfluidity as universal emergent phenomena in diverse physical systems
International Nuclear Information System (INIS)
Guidry, Mike
2014-01-01
Superconductivity and superfluidity are observed across a strikingly broad range of physical systems. This universality seems unlikely to be coincidental but a unified understanding of superconductivity and superfluidity across these highly disparate fields seems impossible in traditional microscopic terms. I give an overview of superconductivity and superfluidity found in various fermionic condensed matter, nuclear physics, and neutron star systems, and propose that all result from generic algebraic structures for the emergent effective Hamiltonian, with the role of underlying microscopic physics largely relegated to influence on parameter values
On the history of creation of the microscopic theories of superfluidity and superconductivity
International Nuclear Information System (INIS)
Bogolyubov, P.N.; Isaev, P.S.
2002-01-01
The history of creation of the microscopic theory of superfluidity (1947) and the microscopic theory of superconductivity (1957) is expounded. The paper is dedicated to the 90th anniversary of the birth of our genius contemporary Academician Nikolaj Nikolaevich Bogolyubov
Goldstone mode and pair-breaking excitations in atomic Fermi superfluids
Hoinka, Sascha; Dyke, Paul; Lingham, Marcus G.; Kinnunen, Jami J.; Bruun, Georg M.; Vale, Chris J.
2017-10-01
Spontaneous symmetry breaking is a central paradigm of elementary particle physics, magnetism, superfluidity and superconductivity. According to Goldstone's theorem, phase transitions that break continuous symmetries lead to the existence of gapless excitations in the long-wavelength limit. These Goldstone modes can become the dominant low-energy excitation, showing that symmetry breaking has a profound impact on the physical properties of matter. Here, we present a comprehensive study of the elementary excitations in a homogeneous strongly interacting Fermi gas through the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) of molecules using two-photon Bragg spectroscopy. The spectra exhibit a discrete Goldstone mode, associated with the broken-symmetry superfluid phase, as well as pair-breaking single-particle excitations. Our techniques yield a direct determination of the superfluid pairing gap and speed of sound in close agreement with strong-coupling theories.
Critical velocities in He II for independently varied superfluid and normal fluid velocities
International Nuclear Information System (INIS)
Baehr, M.L.
1984-01-01
Experiments were performed to measure the critical velocity in pure superflow and compare to the theoretical prediction; to measure the first critical velocity for independently varied superfluid and normal fluid velocities; and to investigate the propagation of the second critical velocity from the thermal counterflow line through the V/sub n/,-V/sub s/ quadrant. The experimental apparatus employed a thermal counterflow heater to adjust the normal fluid velocity, a fountain pump to vary the superfluid velocity, and a level sensing capacitor to measure the superfluid velocity. The results of the pure superfluid critical velocity measurements indicate that this velocity is temperature independent contrary to Schwarz's theory. It was found that the first critical velocity for independently varied V/sub n/ and V/sub s/ could be described by a linear function of V/sub n/ and was otherwise temperature independent. It was found that the second critical velocity could only be distinguished near the thermal counterflow line
Discovery of superfluid 3He phases wins 1996 nobel prize in physics
International Nuclear Information System (INIS)
Yan Shousheng
1997-01-01
The 1996 Nobel prize in physics was awarded to David M. Lee, Douglas D. Osheroff and Robert C. Richardson for their discovery of superfluidity in 3 He in 1971. A short account of the discovery and its importance is given
Gauge-field model of superfluid turbulence in the zero-temperature limit
Mehrafarin, M.
2018-02-01
We present a gauge-field extension of the Bose condensate model that describes T≈0 superfluid turbulence generated by the macroscopic motion of the superfluid. We first establish that the condensate model is dual to the short-range interacting loop gas model, wherein the loops represent quantum vortex lines. Vortex lines form, interact and proliferate as a result of the superfluid motion. Our extension is based on incorporating the Biot–Savart interaction between vortex lines, which is lacking in the loop gas model. We show that the extended loop gas is dual to a Ginzburg–Landau model, wherein the gauge coupling is between the macroscopic velocity field of the superfluid and the condensate. Applying the model to cylindrical and pipe flows, we describe how turbulence transitions with and without intermediate vortex flow, respectively.
Quantum Rabi model in a superfluid Bose-Einstein condensate
Felicetti, S.; Romero, G.; Solano, E.; Sabín, C.
2017-09-01
We propose a quantum simulation of the quantum Rabi model in an atomic quantum dot, which is a single atom in a tight optical trap coupled to the quasiparticle modes of a superfluid Bose-Einstein condensate. This widely tunable setup allows us to simulate the ultrastrong coupling regime of light-matter interaction in a system which enjoys an amenable characteristic time scale, paving the way for an experimental analysis of the transition between the Jaynes-Cummings and the quantum Rabi dynamics using cold-atom systems. Our scheme can be naturally extended to simulate multiqubit quantum Rabi models. In particular, we discuss the appearance of effective two-qubit interactions due to phononic exchange, among other features.
Two-Dimensional Superfluidity of Exciton Polaritons Requires Strong Anisotropy
Directory of Open Access Journals (Sweden)
Ehud Altman
2015-02-01
Full Text Available Fluids of exciton polaritons, excitations of two-dimensional quantum wells in optical cavities, show collective phenomena akin to Bose condensation. However, a fundamental difference from standard condensates stems from the finite lifetime of these excitations, which necessitates continuous driving to maintain a steady state. A basic question is whether a two-dimensional condensate with long-range algebraic correlations can exist under these nonequilibrium conditions. Here, we show that such driven two-dimensional Bose systems cannot exhibit algebraic superfluid order except in low-symmetry, strongly anisotropic systems. Our result implies, in particular, that recent apparent evidence for Bose condensation of exciton polaritons must be an intermediate-scale crossover phenomenon, while the true long-distance correlations fall off exponentially. We obtain these results through a mapping of the long-wavelength condensate dynamics onto the anisotropic Kardar-Parisi-Zhang equation.
Collective Modes of a Soliton Train in a Fermi Superfluid.
Dutta, Shovan; Mueller, Erich J
2017-06-30
We characterize the collective modes of a soliton train in a quasi-one-dimensional Fermi superfluid, using a mean-field formalism. In addition to the expected Goldstone and Higgs modes, we find novel long-lived gapped modes associated with oscillations of the soliton cores. The soliton train has an instability that depends strongly on the interaction strength and the spacing of solitons. It can be stabilized by filling each soliton with an unpaired fermion, thus forming a commensurate Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase. We find that such a state is always dynamically stable, which paves the way for realizing long-lived FFLO states in experiments via phase imprinting.
Transient heat transfer in superfluid helium. Part II
International Nuclear Information System (INIS)
Dresner, L.
1983-01-01
Three classical problems associated with the ordinary diffusion equation concern the temperature in: (1) a half-space with clamped heat flux at the free face, (2) a half-space with clamped temperature at the free face, and (3) an infinite medium with a pulsed plane heat source. These problems are also important for the nonlinear diffusion equation based on the Gorter-Mellink relation, which describes heat transport in superfluid helium. A similarity solution to problem (1), the clamped-flux problem, has already been found and compared, with good agreement, with experimental data of van Sciver. [A similarity solution is one in which the profiles of temperature rise δT versus distance Z at different times t can be obtained from one another by suitable (different) stretching of the temperature and distance axes.] In this paper, similarity solutions are given in analytic form to problems (2) and (3), the clamped-temperature and pulsed-source problems
In situ/non-contact superfluid density measurement apparatus
Nam, Hyoungdo; Su, Ping-Hsang; Shih, Chih-Kang
2018-04-01
We present a double-coil apparatus designed to operate with in situ capability, which is strongly desired for superconductivity studies on recently discovered two-dimensional superconductors. Coupled with a scanning tunneling microscope, the study of both local and global superconductivity [for superconducting gap and superfluid density (SFD), respectively] is possible on an identical sample without sample degradations due to damage, contamination, or oxidation in an atmosphere. The performance of the double-coil apparatus was tested on atomically clean surfaces of non-superconducting Si(111)-7 × 7 and on superconducting films of 100 nm-thick Pb and 1.4 nm-ultrathin Pb. The results clearly show the normal-to-superconductor phase transition for Pb films with a strong SFD.
Ultra-High Q Acoustic Resonance in Superfluid ^4He
De Lorenzo, L. A.; Schwab, K. C.
2017-02-01
We report the measurement of the acoustic quality factor of a gram-scale, kilohertz-frequency superfluid resonator, detected through the parametric coupling to a superconducting niobium microwave cavity. For temperatures between 400 mK and 50 mK, we observe a T^{-4} temperature dependence of the quality factor, consistent with a 3-phonon dissipation mechanism. We observe Q factors up to 1.4× 10^8, consistent with the dissipation due to dilute ^3He impurities, and expect that significant further improvements are possible. These experiments are relevant to exploring quantum behavior and decoherence of massive macroscopic objects, the laboratory detection of continuous gravitational waves from pulsars, and the probing of possible limits to physical length scales.
A cryogenic axial-centrifugal compressor for superfluid helium refrigeration
Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L
1997-01-01
CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.
Second sound shock waves in rotating superfluid helium
International Nuclear Information System (INIS)
Torczynski, J.R.
1983-01-01
Second sound shock waves have been used to examine the breakdown of superfluidity in bulk He II. The maximum counterflow velocity achieved in this manner was measured at a variety of temperatures and pressures. The results are found to agree with predictions of vortex nucleation theories (Langer and Fisher, 1967) in their pressure and temperature dependences although it was shown that dissipation occurred only near the heater. A simple scaling argument is suggested, assuming breakdown occurs near the heater. A vortex dynamics model of breakdown (following the method of Turner, private communication) is developed. To examine the effect of vorticity on breakdown, second sound shocks were produced in rotating helium. Experiments were performed in which the shocks propagated either along or normal to the axis of rotation, called axial and transverse cases, respectively. In both cases the decay was seen to increase monotonically with the rotation rate. Furthermore, the decay was ongoing rather than being confined to a narrow region near the heater. However, the extraordinary dissipation in the transverse case seemed to be related primarily to the arrival of secondary waves from the heater-sidewall boundary. An explanation of this difference is put forth in terms of vortex nucleation in the bulk fluid, using ideas similar to Crocco's Theorem. In order to examine the breakdown of superfluidity away from walls in nonrotation fluid, spherically converging second shocks were produced. The temperature jumps of the waves were measured, and exact numerical solutions of the two-fluid jump conditions (Moody, 1983) were used to calculate the relative velocity in each case
On the influence of drag effect on acoustic modes in two-condensate relativistic superfluid systems
International Nuclear Information System (INIS)
Vil'chinskij, S.I.
1999-01-01
Equations of velocities of acoustic excitations in a relativistic two-condensate superfluid system are derived with due account of reciprocal drag of superfluid motion (drag effect). The influence of the drag effect on acoustic modes in the system is considered. It is shown that the effect does not influence the nature of acoustic excitation oscillations but produces changes in the velocities of the second, third and fourth sounds
Bulk damping of sound in superfluid 3He--4He under stagnation of the normal component
International Nuclear Information System (INIS)
Karchava, T.A.; Sanikidze, D.G.; Chkhaidze, N.D.
1983-01-01
The propagation of waves in superfluid 3 He-- 4 He solutions is considered under partial stagnation of the normal component. The wave processes in capillaries are presented as a superposition of the first sound, second sound, and viscous and diffusion waves. The damping coefficients are calculated for the modified first sound and for the thermal wave in superfluid 3 He-- 4 He solutions and related to the viscosity, thermal conductivity, diffusion, barodiffusion, and thermodiffusion coefficients
The influence of antikaon condensations on nucleon 1S0 superfluidity in neutron star matter
Xu, Yan; Huang, Xiu Lin; Zhang, Xiao Jun; Yu, Zi; Fan, Cun Bo; Ding, Wen Bo; Liu, Cheng Zhi
2018-03-01
The properties of neutron and proton 1S0 superfluidity are studied within the relativistic mean field and the Bardeen-Cooper-Schrieffer theories by taking the effects of K- and \\bar{K}0 condensations into account in neutron star matter without the hyperon degrees of freedom. It is found that antikaon condensations change the Fermi momenta, the effective masses and the single particle energies of nucleons in neutron star matter. These changes lead to a strong suppression of the neutron 1S0 superfluidity and an obvious enhancement of the proton 1S0 superfluidity in neutron star matter, respectively. In particular, the neutron and proton 1S0 pairing gaps are gradually shrinking with the optical potential of antikaons from -80 to -130 MeV. And antikaon condensations have little influence on the neutron 1S0 superfluid range, however, they have been markedly downsized the proton 1S0 superfluid range as the deepening of the optical potential of antikaons in neutron star matter. We also found that the nucleon 1S0 superfluidity and K- condensations within the scope of above optical potential of antikaons can occur in the core of PSR J1614-2230 and PSR J0348+0432 at the same time. Whereas \\bar{K}0 condensations only occur in the two pulsars when the range of optical potential of antikaons is from -100 to -130 MeV.
Quantum phases of dipolar soft-core bosons
Grimmer, D.; Safavi-Naini, A.; Capogrosso-Sansone, B.; Söyler, Ş. G.
2014-10-01
We study the phase diagram of a system of soft-core dipolar bosons confined to a two-dimensional optical lattice layer. We assume that dipoles are aligned perpendicular to the layer such that the dipolar interactions are purely repulsive and isotropic. We consider the full dipolar interaction and perform path-integral quantum Monte Carlo simulations using the worm algorithm. Besides a superfluid phase, we find various solid and supersolid phases. We show that, unlike what was found previously for the case of nearest-neighbor interaction, supersolid phases are stabilized by doping the solids not only with particles but with holes as well. We further study the stability of these quantum phases against thermal fluctuations. Finally, we discuss pair formation and the stability of the pair checkerboard phase formed in a bilayer geometry, and we suggest experimental conditions under which the pair checkerboard phase can be observed.
Theory of a condensed charged-Bose, charged Fermi gas and Ginzburg--Landau studies of superfluid 3He
International Nuclear Information System (INIS)
Dahl, D.A.
1976-01-01
Two independent topics in the field of condensed matter physics are examined: the condensed charged-Bose, charged Fermi gas and superfluid 3 He. Green's function (field theoretic) methods are used to derive the low-temperature properties of a dense, neutral gas of condensed charged bosons and degenerate charged fermions. Restriction is made to the case where the fermion mass is much lighter than the boson mass. Linear response and the density-density correlation function are examined and shown to exhibit two collective modes: a plasmon branch and a phonon branch with speed equal to that of ionic sound in solids. Comparison with a possible astrophysical application (white dwarf stars) is made. The behavior near the superfluid transition temperature (Ginzburg--Landau regime) of 3 He is then studied. Gorkov equations are derived and studied in the weak-coupling limit. In this way the form and order of magnitude estimates of coefficients appearing in the Ginzburg--Landau theory are obtained. Weak-coupling particle and spin currents are derived. Various perturbations break the large degeneracy of the states and have experimental implications. The electric contribution to the Ginzburg--Landau free energy is studied for the proposed A and B phases. Imposition of an electric field orients the axial state, but does not give rise to shifts in the NMR resonances. Shifts and discontinuous jumps in the longitudinal and transverse signals are predicted for the Balian--Werthamer state, the details depending on the relative strengths of the fields, as well as the angle between them
Crevecoeur, R.M.
1996-01-01
In this thesis we have presented the results of a neutron scattering study of the analogies in the microscopic behavior of superfluid and classical helium. Therefore we performed both neutron-diffraction experiments to study the structure and inelastic neutron scattering experiments to study the
Establishing a Consistent Theory of Transport in Strongly Correlated Fermi Superfluids
Boyack, Rufus M.
A diagrammatic method of obtaining exact gauge-invariant response functions in strongly correlated Fermi superfluids is implemented for several example condensed matter systems of current interest. These include: topological superfluids, high temperature superconductors, and superfluids with finite center-of-mass momentum pairing known as Fulde-Ferrell superfluids. Much of the literature on these systems has focused on single-particle properties or alternatively has invoked simple approximations to treat response functions. The goal is to show that, for this wide class of topical problems, one can compute exact response functions. This enables assessment of the validity of different physical scenarios and allows a very broad class of experiments to be addressed. The method developed is based on deriving the full electromagnetic vertex, which satisfies the Ward-Takahashi identity, and determining the collective modes in a manner compatible with the self-consistent gap equation. In the condensed phase of a superfluid and a superconductor, where gauge invariance is spontaneously broken, it is crucial to determine the collective modes from the gap equation in a manner which restores gauge invariance. Our diagrammatic framework provides a very general and powerful method for obtaining these collective modes in a variety of strongly correlated Fermi superfluids. We show that a full electromagnetic vertex satisfying the Ward-Takahashi identity ensures the f-sum rule is satisfied and thus charge is conserved. This diagrammatic method is implemented for both normal and superfluid phases. While there are no collective modes in the normal phase, the Ward-Takahashi identity plays a similarly important role. In particular, for the normal phase we study Rashba spin-orbit coupled Fermi gases with intrinsic pairing in the absence and presence of a magnetic field. Exact density and spin response functions are obtained, even in the absence of a spin conservation law, providing
Mongiovì, Maria Stella; Jou, David; Sciacca, Michele
2018-01-01
This review paper puts together some results concerning non equilibrium thermodynamics and heat transport properties of superfluid He II. A one-fluid extended model of superfluid helium, which considers heat flux as an additional independent variable, is presented, its microscopic bases are analyzed, and compared with the well known two-fluid model. In laminar situations, the fundamental fields are density, velocity, absolute temperature, and heat flux. Such a theory is able to describe the thermomechanical phenomena, the propagation of two sounds in liquid helium, and of fourth sound in superleak. It also leads in a natural way to a two-fluid model on purely macroscopical grounds and allows a small amount of entropy associated with the superfluid component. Other important features of liquid He II arise in rotating situations and in superfluid turbulence, both characterized by the presence of quantized vortices (thin vortex lines whose circulation is restricted by a quantum condition). Such vortices have a deep influence on the transport properties of superfluid helium, as they increase very much its thermal resistance. Thus, heat flux influences the vortices which, in turn, modify the heat flux. The dynamics of vortex lines is the central topic in turbulent superfluid helium. The model is generalized to take into account the vortices in different cases of physical interest: rotating superfluids, counterflow superfluid turbulence, combined counterflow and rotation, and mass flow in addition to heat flow. To do this, the averaged vortex line density per unit volume L, is introduced and its dynamical equations are considered. Linear and non-linear evolution equations for L are written for homogeneous and inhomogeneous, isotropic and anisotropic situations. Several physical experiments are analyzed and the influence of vortices on the effective thermal conductivity of turbulent superfluid helium is found. Transitions from laminar to turbulent flows, from diffusive to
Pinned vorticity in rotating superfluids, with application to neutron stars
International Nuclear Information System (INIS)
Pines, D.; Shaham, J.; Alpar, M.A.; Anderson, P.W.
1981-01-01
The dynamic consequences of the existence of pinned vorticity in a rotating superfluid are studied by means of a simple model: the behavior of a rotating cylinder which contains a uniform region of either weakly or strongly pinned vorticity and which is being spun up or spun down by an external torque. It is shown that in the case of strong pinning, spin down can lead to periodic jumps (glitches) in the rotation frequency of the cylinder, followed by quasi-oscillatory relaxation, while in the case of weak pinning no glitches occur unless the cylinder is shaken so violently that vortices unpin. We conclude that the giant glitches and post-glitch behavior observed in the Vela pulsar may be explained by the sudden release of some 10% of the strongly pinned vortices in the neutron crust every few years as a result of pulsar spin down. We further suggest that the post-glitch behavior observed in the Crab pulsar can be explained if the macroglitches represent vorticity jumps induced by small starquakes in the weakly pinned vortex region expected in the crust of a young neutron star, and that the differences in ''glitch'' behavior of the Crab, Vela, and older pulsars may be explained on evolutionary grounds. (author)
The breakdown of superfluidity in liquid 4He
International Nuclear Information System (INIS)
Bowley, R.M.; McClintock, P.V.E.; Moss, F.E.; Nancolas, G.G.; Stamp, P.C.E.
1982-01-01
The rate, ν, at which negative ions nucleate charge vortex rings in isotopically pure superfluid 4 He has been measured for pressures, P 1 (15 - 25 bar), temperatures, T 1 (0.3 - 0.9K), and electric fields E (5 x 10 4 - 10 6 Vm -1 ). The measurements were done by a novel electrostatic induction technique specially developed for the purpose, and this is described in detail. Results are given. In all cases, ν was found to be considerably smaller than had been measured for low E by earlier workers using helium of the natural isotopic ratio (ca. 2 x 10 -7 ). Ionic drift velocities v-bar, were measured for ν less than ca. 3 x 10 4 s -1 . Values of the matrix element for roton pair emission have been deduced from the v-bar(E) measurements in the range 17 approximately vsub(v) (or vsub(r)); this is the first experimental evidence that the microscopic mechanisms responsible for vortex nucleation are probabilistic in nature. (U.K.)
Momentum, vorticity, and helicity in covariant superfluid dynamics
International Nuclear Information System (INIS)
Carter, B.; Khalatnikov, I.M.
1992-01-01
The convective and potential variational principles that can be used for alternative derivations of the same natural relativistic generalisation of the standard Landau theory of perfect superfluid dynamics are both characterised by the feature that, instead of attributing special importance to a partition in terms of certain non-conserved open-quotes superfluidclose quotes and open-quotes normalclose quotes current vectors j v s and j v N they accord a much more prominent role to certain open-quotes particleclose quotes and open-quotes thermalclose quotes momentum convectors μ v and Θ v of which the latter in particular has been unduly neglected in traditional discussions. The present article discusses the interdependence and the dynamic evolution of these quantities, drawing attention to consequences such as the conservation of the flux associated with the open-quotes thermal velocityclose quotes form W μv , and the conservation of the related open-quotes thermal helicityclose quotes current H v . The comparison of this theory with some other conducting fluid theories is briefly discussed, and more particularly it is shown explicitly how this generalisation of the fully non-linear Landau theory relates to an analogous generalisation of the more restricted type of theory previously developed by Tisza and London, in which the quantities j v s and j v N had a more fundamental role. 40 refs., 1 fig., 1 tab
Longitudinal nuclear magnetic resonance of 3He-B superfluid
International Nuclear Information System (INIS)
Vibet, Claude.
1979-06-01
Experiments which contribute to a better understanding of the 3 He superfluid in the B phase are reported: a/ The first direct determinations of the gap parameter at zero temperature are given and the longitudinal N.M.R. frequency signal is measured for various pressures. b/ These experiments show a new saturation phenomenon in the ringing signal decay time Tsub(R)(T) at low temperatures. c/ Under conditions of slight non-linearity the excitation of 3 He-B longitudinal N.M.R. gives rise to a special system wherein the ringing signal decay is all the faster as the excitation is stronger. A so-called ''memory'' time is measured distinctly longer than the ringing time measured under quasi-linear excitation conditions. It was found that the ringing signal decay, at first exponential for weak excitations γH 1 approximately 7 10 -3 Ωsub(L), becomes quasi-linear when the excitation is about γH 1 approximately 10 -2 Ωsub(L). This abnormal behaviour cannot be explained by thermal effects related to N.M.R. excitation nor by inhomogeneity effects of the excitation magnetic field. Our interpretation is that excitations γH 1 approximately 10 -2 Ωsub(L) cause structural defects in the orientation of the vector n which are found to disappear according to an exponential law in times of around 10 ms [fr
Heat-capacity scaling function for confined superfluids
International Nuclear Information System (INIS)
Nho, Kwangsik; Manousakis, Efstratios
2003-01-01
We study the specific-heat scaling function of confined superfluids using Monte Carlo simulation. While the scaling function is insensitive to the microscopic details, it depends on the confining geometry and boundary conditions (BC's). In the present work we have studied (a) cubic geometry with open BC's in all three directions and (b) parallel-plate (film) geometry using open BC's along the finite dimension and periodic BC's along the other two dimensions. We find that the specific-heat scaling function is significantly different for the two different geometries studied. The scaling function for each geometry (a) or (b) is very different when compared to that obtained for the same geometry but with periodic BC's. On the contrary, we find that in case (b) the calculated scaling function is very close to the earlier calculated using Dirichlet instead of open BC's. This demonstrates that Dirichlet and open boundary conditions act in a similar way. Our results for both scaling functions obtained for the parallel-plate geometry and for cubic geometry with open BC's along the finite dimensions are in very good agreement with recent very-high-quality experimental measurements with no free parameters
Superfluid phase transition with activated velocity fluctuations: Renormalization group approach
Dančo, Michal; Hnatič, Michal; Komarova, Marina V.; Lučivjanský, Tomáš; Nalimov, Mikhail Yu.
2016-01-01
A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within the perturbative renormalization group method. The double (ɛ ,δ ) -expansion scheme is employed, where ɛ is a deviation from space dimension 4 and δ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value 4 /3 .
Superfluid phase transition with activated velocity fluctuations: Renormalization group approach.
Dančo, Michal; Hnatič, Michal; Komarova, Marina V; Lučivjanský, Tomáš; Nalimov, Mikhail Yu
2016-01-01
A quantum field model that incorporates Bose-condensed systems near their phase transition into a superfluid phase and velocity fluctuations is proposed. The stochastic Navier-Stokes equation is used for a generation of the velocity fluctuations. As such this model generalizes model F of critical dynamics. The field-theoretic action is derived using the Martin-Siggia-Rose formalism and path integral approach. The regime of equilibrium fluctuations is analyzed within the perturbative renormalization group method. The double (ε,δ)-expansion scheme is employed, where ε is a deviation from space dimension 4 and δ describes scaling of velocity fluctuations. The renormalization procedure is performed to the leading order. The main corollary gained from the analysis of the thermal equilibrium regime suggests that one-loop calculations of the presented models are not sufficient to make a definite conclusion about the stability of fixed points. We also show that critical exponents are drastically changed as a result of the turbulent background and critical fluctuations are in fact destroyed by the developed turbulence fluctuations. The scaling exponent of effective viscosity is calculated and agrees with expected value 4/3.
Neutron Matter as a Composite Bose-Fermi Superfluid
Arbanas, Goran; Kerman, Arthur; Nam, Hai Ah; Stone, Jirina
2011-10-01
We model infinite neutron matter as an interacting Bose-Fermi superfluid consisting of superconducting neutrons and a Bose-Einstein condensate of a six-quark Feshbach state. The interaction term in the many-body grand canonical Hamiltonian is defined by a coupling form-factor and a coupling strength that are determined by fitting an expression for neutron-neutron scattering (via the same Feshbach state) to the 1S0 phase shift. Extremization of the expectation value of the grand canonical Hamiltonian in the ground state yields an equation of state for infinite neutron matter that we numerically solve for particle-number densities between 10-7 and 0.5 fm-3. In the unitary limit (i.e., infinite scattering length and a zero effective range), we find the energy per particle to be 0.6 that of a free Fermi gas. The effect of random-phase-approximation corrections to our equation of state is addressed. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy.
Maria Goeppert Mayer Prize Talk: Superfluid Atom Circuits
Campbell, Gretchen
2016-05-01
We have performed a series of experiments with ring-shaped Bose-Einstein Condensates, with and without the addition of a ``weak link'' barrier. Weak connections between superconductors or superfluids can differ from classical links due to quantum coherence, which allows for flow without resistance. The properties of a weak link are characterized by a single function, the current-phase relationship. In recent experiments, we have developed a technique to directly measure the current-phase relationship of the weak link. The weak link is created using a laser beam that acts as a barrier across one side of the ring condensate. By rotating the barrier, we can control the current around the ring. When the weak link is rotated at at low rotation rates, we observe phase slips between well-defined, quantized current states, and have demonstrated that the system exhibits hysteresis. At higher rotation rates we have directly measured the onset of resistive flow across the weak link. Such measurements may open new avenues of research in quantum transport. More recently, we have studied the behavior of the ring BEC when the radius is expanded at supersonic rates. Because information can propagate only at the speed of sound, the supersonic expansion creates causally disconnected regions, whose phases evolve at different rates. Such experiments may allow us to study cosmic inflation at laboratory scales.
Quantum Monte Carlo studies of superfluid Fermi gases
International Nuclear Information System (INIS)
Chang, S.Y.; Pandharipande, V.R.; Carlson, J.; Schmidt, K.E.
2004-01-01
We report results of quantum Monte Carlo calculations of the ground state of dilute Fermi gases with attractive short-range two-body interactions. The strength of the interaction is varied to study different pairing regimes which are characterized by the product of the s-wave scattering length and the Fermi wave vector, ak F . We report results for the ground-state energy, the pairing gap Δ, and the quasiparticle spectrum. In the weak-coupling regime, 1/ak F FG . When a>0, the interaction is strong enough to form bound molecules with energy E mol . For 1/ak F > or approx. 0.5, we find that weakly interacting composite bosons are formed in the superfluid gas with Δ and gas energy per particle approaching E mol /2. In this region, we seem to have Bose-Einstein condensation (BEC) of molecules. The behavior of the energy and the gap in the BCS-to-BEC transition region, -0.5 F <0.5, is discussed
Faraday instability and Faraday patterns in a superfluid Fermi gas
International Nuclear Information System (INIS)
Tang Rongan; Xue Jukui; Li Haocai
2011-01-01
With the consideration of the coupling between the transverse width and the longitudinal density, the parametric excitations related to Faraday waves in a cigar-shaped superfluid Fermi gas are studied. A Mathieu equation is obtained, and it is demonstrated firstly that the excited actual 3D Faraday pattern is the combination of the longitudinal Faraday density wave and the corresponding transverse width fluctuation in the longitudinal direction. The Faraday instability growth index and the kinematic equations of the Faraday density wave and the width fluctuation along the Bose-Einstein condensate (BEC)-Bardeen-Cooper-Schrieffer (BCS) crossover are also given for the first time. It is found that the 3D Faraday pattern presents quite different behaviours (such as the excitations and the motions) when the system crosses from the BEC side to the BCS side. The coupling not only plays an important role in the parametric excitation, but also determines the dominant wavelength of the spatial structure. Along the crossover, the coupling effects are more significant in the BCS side. The final numerical investigation verifies these results and gives a detailed study of the parametric excitations (i.e. Faraday instability) and the 3D pattern formation.
Examining empirical evidence of the effect of superfluidity on the fusion barrier
Scamps, Guillaume
2018-04-01
Background: Recent time-dependent Hartree-Fock-Bogoliubov (TDHFB) calculations predict that superfluidity enhances fluctuations of the fusion barrier. This effect is not fully understood and not yet experimentally revealed. Purpose: The goal of this study is to empirically investigate the effect of superfluidity on the distribution width of the fusion barrier. Method: Two new methods are proposed in the present study. First, the local regression method is introduced and used to determine the barrier distribution. The second method, which requires only the calculation of an integral of the cross section, is developed to determine accurately the fluctuations of the barrier. This integral method, showing the best performance, is systematically applied to 115 fusion reactions. Results: Fluctuations of the barrier for open-shell systems are, on average, larger than those for magic or semimagic nuclei. This is due to the deformation and the superfluidity. To disentangle these two effects, a comparison is made between the experimental width and the width estimated from a model that takes into account the tunneling, the deformation, and the vibration effect. This study reveals that superfluidity enhances the fusion barrier width. Conclusions: This analysis shows that the predicted effect of superfluidity on the width of the barrier is real and is of the order of 1 MeV.
Investigation of thermal transfers in super-fluid helium in porous media
International Nuclear Information System (INIS)
Allain, H.
2009-10-01
Particle accelerators are requiring increased magnetic fields for which niobium tin superconducting magnets are considered. This entails electric insulation and cooling problems. Porous ceramic insulations are potential candidates for cable insulation. As they are permeable to helium, they could allow a direct cooling by super-fluid helium. Therefore, this research thesis deals with the investigation of thermal transfers in superfluid helium in porous media. After a description of an accelerator's superconducting magnet, of its thermodynamics and its various cooling modes, the author describes the physical properties of super-fluid helium, its peculiarities with respect to conventional fluids as well as its different phases (fluid and super-fluid), its dynamics under different regimes (the Landau regime which is similar to the laminar regime for a conventional fluid, and the Gorter-Mellink regime which is the super-fluid turbulent regime). He determines the macroscopic equations governing the He II dynamics in porous media by applying the volume averaging method developed by Whitaker. Theoretical results are validated by comparison with a numerical analysis performed with a numerical code. Then, the author presents the various experimental setups which have been developed for the measurement of the intrinsic permeability, one at room temperature and another at high temperature. Experimental results are discussed, notably with respect to pore size and porosity
QCM study of superfluid transition in 4He films adsorbed in SBA-15
International Nuclear Information System (INIS)
Matsuda, K; Hieda, M; Matsushita, T; Wada, N; Suzuki, T; Kuroda, K
2009-01-01
A quartz crystal microbalance (QCM) is a useful tool to study the superfluidity of 4 He films at very high frequencies. Our recent efforts to fabricate mesoporous silica films onto QCM have enabled us to study the noble superfluidity adsorbed in nanopores. In this paper we report results of QCM measurements for the superfluid 4 He films in SBA-15 with one-dimensional nanopores 4.1 nm in diameter and ∼ 1 μM in length. From the 4 He pressure isotherm at 4.2 K, a uniform layer is formed in the nanopores up to the coverage of 48 μmol/m 2 , corresponding to ∼ 2.5 layers. The superfluid response is measured at 12 MHz for various coverages in the temperature range of 0.1 - 1.5 K. Above the onset coverage of ∼ 23 μmol/m 2 , we observed a frequency shift accompanied by a dissipation peak due to the superfluid Kosterlitz-Thouless (KT) transition.
Depression of the Superfluid Transition Temperature in 4He by a Heat Flow
International Nuclear Information System (INIS)
Yin Liang; Qi Xin; Lin Peng
2014-01-01
The depression of the superfluid transition temperature T λ in 4 He by a heat flow Q is studied. A small sealed cell with a capillary is introduced and a stable and flat superfluid transition temperature plateau is easily obtained by controlling the temperature of the variable-temperature platform and the bottom chamber of the sealed cell. Owing to the depression effect of the superfluid transition temperature by the heat flow, the heat flow through the capillary is changed by the temperature control to obtain multiple temperature plateaus of different heat flows. The thermometer self-heating effect, the residual heat leak of the 4.2 K environment, the temperature difference on the He II liquid column, the Kapiza thermal resistance between the liquid helium and the copper surface of the sealed cell, the temperature gradient of the sealed cell, the static pressure of the He II liquid column and other factors have influence on the depression effect and the influence is analyzed in detail. Twenty experiments of the depression of the superfluid transition temperature in 4 He by heat flow are made with four sealed cells in one year. The formula of the superfluid transition temperature pressured by the heat flow is T λ (Q) = −0.00000103Q + 2.1769108, and covers the range 229 ≤ Q ≤ 6462 μW/cm 2
International Nuclear Information System (INIS)
Lopatnikova, A.; Berker, A.N.
1997-01-01
Superfluidity and phase separation in 3 He- 4 He mixtures immersed in aerogel are studied by renormalization-group theory. The quenched disorder imposed by aerogel, both at the atomic level and at the geometric level, is included. The calculation is conducted via the coupled renormalization-group mappings, near and away from aerogel, of the quenched probability distributions of random interactions. Random-bond effects on the onset of superfluidity and random-field effects on superfluid-superfluid phase separation are seen. The quenched randomness causes the λ line of second-order phase transitions of superfluidity onset to reach zero temperature, in agreement with general predictions and experiments. The effects of the atomic and geometric randomness of aerogel are investigated separately and jointly. copyright 1997 The American Physical Society
Granieri, Pier Paolo; Tommasini, D
In this thesis work we investigate the heat transfer through the electrical insulation of superconducting cables cooled by superfluid helium. The cable insulation constitutes the most severe barrier for heat extraction from the superconducting magnets of the CERN Large Hadron Collider (LHC). We performed an experimental analysis, a theoretical modeling and a fundamental research to characterize the present LHC insulation and to develop new ideas of thermally enhanced insulations. The outcome of these studies allowed to determine the thermal stability of the magnets for the LHC and its future upgrades. An innovative measurement technique was developed to experimentally analyze the heat transfer between the cables and the superfluid helium bath. It allowed to describe the LHC coil behavior using the real cable structure, an appropriate thermometry and controlling the applied pressure. We developed a new thermally enhanced insulation scheme based on an increased porosity to superfluid helium. It aims at withstan...
Interferometric Measurement of the Current-Phase Relationship of a Superfluid Weak Link
Directory of Open Access Journals (Sweden)
S. Eckel
2014-09-01
Full Text Available Weak connections between superconductors or superfluids can differ from classical links due to quantum coherence, which allows flow without resistance. Transport properties through such weak links can be described with a single function, the current-phase relationship, which serves as the quantum analog of the current-voltage relationship. Here, we present a technique for inteferometrically measuring the current-phase relationship of superfluid weak links. We interferometrically measure the phase gradient around a ring-shaped superfluid Bose-Einstein condensate containing a rotating weak link, allowing us to identify the current flowing around the ring. While our Bose-Einstein condensate weak link operates in the hydrodynamic regime, this technique can be extended to all types of weak links (including tunnel junctions in any phase-coherent quantum gas. Moreover, it can also measure the current-phase relationships of excitations. Such measurements may open new avenues of research in quantum transport.
International Nuclear Information System (INIS)
Dave, Shreyansh Shanker; Bagchi, Partha; Srivastava, Ajit M.; Das, Arpan; Sengupta, Srikumar
2016-01-01
High baryon density regions of the cores of neutron stars are expected to have exotic phases such as color superconducting phases. The symmetry breaking pattern of these phases allows for topological vortices. Even in the lower density region of neutron star, neutron superfluid and associated topological vortices play important role in the dynamics of neutron star, e.g. in pulsar timings and glitches. We consider the possibility of formation of these superfluid phases in heavy-ion collision experiments, e.g. at FAIR and NICA, by carrying out Hydrodynamic simulation. Our result shows that existence of superfluid phases can be detected by studying the effect of vortices on power spectrum of flow fluctuations. (author)
Analytical study on holographic superfluid in AdS soliton background
Energy Technology Data Exchange (ETDEWEB)
Lai, Chuyu [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China); Pan, Qiyuan, E-mail: panqiyuan@126.com [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China); Instituto de Física, Universidade de São Paulo, CP 66318, São Paulo 05315-970 (Brazil); Jing, Jiliang, E-mail: jljing@hunnu.edu.cn [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China); Wang, Yongjiu, E-mail: wyj@hunnu.edu.cn [Department of Physics, Key Laboratory of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, Hunan Normal University, Changsha, Hunan 410081 (China); Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha, Hunan 410081 (China)
2016-06-10
We analytically study the holographic superfluid phase transition in the AdS soliton background by using the variational method for the Sturm–Liouville eigenvalue problem. By investigating the holographic s-wave and p-wave superfluid models in the probe limit, we observe that the spatial component of the gauge field will hinder the phase transition. Moreover, we note that, different from the AdS black hole spacetime, in the AdS soliton background the holographic superfluid phase transition always belongs to the second order and the critical exponent of the system takes the mean-field value in both s-wave and p-wave models. Our analytical results are found to be in good agreement with the numerical findings.
Superfluid stirling refrigerator: A new method for cooling below 1 Kelvin
International Nuclear Information System (INIS)
Kotsubo, V.; Swift, G.W.
1990-01-01
We have invented and built a new type of cryocooler, which we call the superfluid Stirling refrigerator (SSR). The first prototype reached 0.6 K from a starting temperature of 1.2 K. The working fluid of the SSR is the 3 He solute in a superfluid 3 He-- 4 He solution. At low temperatures, the superfluid 4 He is in its quantum ground state, and therefore is thermodynamically inert, while the 3 He solute has the thermodynamic properties of a dense ideal gas. Thus, in principle, any refrigeration cycle that can use an ideal gas can also use the 3 He solute as working fluid. In our SSR prototype, bellows-sealed superleak pistons driven by a room-temperature camshaft work on the 3 He solute. Ultimately, we anticipate elimination of moving parts by analogy with pulse-tube refrigeration. 15 refs., 6 figs
Effective theory of vortices in two-dimensional spinless chiral p -wave superfluids
Ariad, Daniel; Grosfeld, Eytan; Seradjeh, Babak
2015-07-01
We propose a U (1 ) ×Z2 effective gauge theory for vortices in a px+i py superfluid in two dimensions. The combined gauge transformation binds U (1 ) and Z2 defects so that the total transformation remains single-valued and manifestly preserves the particle-hole symmetry of the action. The Z2 gauge field introduces a complete Chern-Simons term in addition to a partial one associated with the U (1 ) gauge field. The theory reproduces the known physics of vortex dynamics such as a Magnus force proportional to the superfluid density. More importantly, it predicts a universal Abelian phase, exp(i π /8 ) , upon the exchange of two vortices. This phase is modified by nonuniversal corrections due to the partial Chern-Simon term, which are nevertheless screened in a charged superfluid at distances that are larger than the penetration depth.
Hydrodynamical model of anisotropic, polarized turbulent superfluids. I: constraints for the fluxes
Mongiovì, Maria Stella; Restuccia, Liliana
2018-02-01
This work is the first of a series of papers devoted to the study of the influence of the anisotropy and polarization of the tangle of quantized vortex lines in superfluid turbulence. A thermodynamical model of inhomogeneous superfluid turbulence previously formulated is here extended, to take into consideration also these effects. The model chooses as thermodynamic state vector the density, the velocity, the energy density, the heat flux, and a complete vorticity tensor field, including its symmetric traceless part and its antisymmetric part. The relations which constrain the constitutive quantities are deduced from the second principle of thermodynamics using the Liu procedure. The results show that the presence of anisotropy and polarization in the vortex tangle affects in a substantial way the dynamics of the heat flux, and allow us to give a physical interpretation of the vorticity tensor here introduced, and to better describe the internal structure of a turbulent superfluid.
Superfluid and antiferromagnetic phases in ultracold fermionic quantum gases
Energy Technology Data Exchange (ETDEWEB)
Gottwald, Tobias
2010-08-27
In this thesis several models are treated, which are relevant for ultracold fermionic quantum gases loaded onto optical lattices. In particular, imbalanced superfluid Fermi mixtures, which are considered as the best way to realize Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states experimentally, and antiferromagnetic states, whose experimental realization is one of the next major goals, are examined analytically and numerically with the use of appropriate versions of the Hubbard model. The usual Bardeen-Cooper-Schrieffer (BCS) superconductor is known to break down in a magnetic field with a strength exceeding the size of the superfluid gap. A spatially inhomogeneous spin-imbalanced superconductor with a complex order parameter known as FFLO-state is predicted to occur in translationally invariant systems. Since in ultracold quantum gases the experimental setups have a limited size and a trapping potential, we analyze the realistic situation of a non-translationally invariant finite sized Hubbard model for this purpose. We first argue analytically, why the order parameter should be real in a system with continuous coordinates, and map our statements onto the Hubbard model with discrete coordinates defined on a lattice. The relevant Hubbard model is then treated numerically within mean field theory. We show that the numerical results agree with our analytically derived statements and we simulate various experimentally relevant systems in this thesis. Analogous calculations are presented for the situation at repulsive interaction strength where the N'eel state is expected to be realized experimentally in the near future. We map our analytical results obtained for the attractive model onto corresponding results for the repulsive model. We obtain a spatially invariant unit vector defining the direction of the order parameter as a consequence of the trapping potential, which is affirmed by our mean field numerical results for the repulsive case. Furthermore, we observe
Superfluid and antiferromagnetic phases in ultracold fermionic quantum gases
International Nuclear Information System (INIS)
Gottwald, Tobias
2010-01-01
In this thesis several models are treated, which are relevant for ultracold fermionic quantum gases loaded onto optical lattices. In particular, imbalanced superfluid Fermi mixtures, which are considered as the best way to realize Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states experimentally, and antiferromagnetic states, whose experimental realization is one of the next major goals, are examined analytically and numerically with the use of appropriate versions of the Hubbard model. The usual Bardeen-Cooper-Schrieffer (BCS) superconductor is known to break down in a magnetic field with a strength exceeding the size of the superfluid gap. A spatially inhomogeneous spin-imbalanced superconductor with a complex order parameter known as FFLO-state is predicted to occur in translationally invariant systems. Since in ultracold quantum gases the experimental setups have a limited size and a trapping potential, we analyze the realistic situation of a non-translationally invariant finite sized Hubbard model for this purpose. We first argue analytically, why the order parameter should be real in a system with continuous coordinates, and map our statements onto the Hubbard model with discrete coordinates defined on a lattice. The relevant Hubbard model is then treated numerically within mean field theory. We show that the numerical results agree with our analytically derived statements and we simulate various experimentally relevant systems in this thesis. Analogous calculations are presented for the situation at repulsive interaction strength where the N'eel state is expected to be realized experimentally in the near future. We map our analytical results obtained for the attractive model onto corresponding results for the repulsive model. We obtain a spatially invariant unit vector defining the direction of the order parameter as a consequence of the trapping potential, which is affirmed by our mean field numerical results for the repulsive case. Furthermore, we observe
Logarithmic effects on the critical behavior of superfluids in random media
International Nuclear Information System (INIS)
Narayan, O.; Fisher, D.S.
1990-01-01
The effects of logarithmic corrections on the critical behavior of systems near a phase transition with marginally irrelevant quenched disorder are examined, specifically in the context of superfluid 4 He in porous media. It is argued that these corrections are likely to change the critical behavior of the specific heat to an inverse logarithmic cusp, and alter, to a new universal constant, the magnitude of the amplitude ratio relating the critical specific heat to the superfluid density. An var-epsilon expansion is carried out along the line on which the randomness is marginal. The results also have implications for the behavior of dirty high-temperature superconductors
Prospects of Detecting Baryon and Quark Superfluidity from Cooling Neutron Stars
Page, Dany; Prakash, Madappa; Lattimer, James M.; Steiner, Andrew
2000-01-01
Baryon and quark superfluidity in the cooling of neutron stars are investigated. Observations could constrain combinations of the neutron or Lambda-hyperon pairing gaps and the star's mass. However, in a hybrid star with a mixed phase of hadrons and quarks, quark gaps larger than a few tenths of an MeV render quark matter virtually invisible for cooling. If the quark gap is smaller, quark superfluidity could be important, but its effects will be nearly impossible to distinguish from those of ...
Prospects of detecting baryon and quark superfluidity from cooling neutron stars
Page; Prakash; Lattimer; Steiner
2000-09-04
Baryon and quark superfluidity in the cooling of neutron stars are investigated. Future observations will allow us to constrain combinations of the neutron or Lambda-hyperon pairing gaps and the star's mass. However, in a hybrid star with a mixed phase of hadrons and quarks, quark gaps larger than a few tenths of an MeV render quark matter virtually invisible for cooling. If the quark gap is smaller, quark superfluidity could be important, but its effects will be nearly impossible to distinguish from those of other baryonic constituents.
Parity violating superfluidity in ultra-cold atoms with artificial non-Abelian gauge fields
Han, Li; Seo, Kangjun; Sá de Melo, Carlos
2013-04-01
We discuss the creation of parity violating Fermi superfluids in the presence of non-Abelian gauge fields realized by artificial spin-orbit coupling and crossed Zeeman fields. Unlike the case in particle physics where the parity violation is driven by weak interaction, the parity breaking is due to the effects of non-Abelian gauge fields on the kinetic energy in our system. We analyze the signatures of parity violation on the excitation spectrum of the system in normal and superfluid phases, as well as ground state properties such as the spin-resolved momentum distribution, and excitation properties such as the spin-dependent spectral function and density of states.
Scale-separation scheme for simulating superfluid turbulence: Kelvin-Wave cascade
International Nuclear Information System (INIS)
Kozik, Evgeny; Svistunov, Boris
2005-01-01
A Kolmogorov-type cascade of Kelvin waves--the distortion waves on vortex lines--plays a key part in the relaxation of superfluid turbulence at low temperatures. We propose an efficient numeric scheme for simulating the Kelvin-wave cascade on a single vortex line. This idea is likely to be generalizable for a full-scale simulation of different regimes of superfluid turbulence. With the new scheme, we are able to unambiguously resolve the cascade spectrum exponent, and thus to settle the controversy between recent simulations of Vinen, Tsubota, and Mitani [Phys. Rev. Lett. 91, 135301 (2003)] and recently developed analytic theory [Phys. Rev. Lett. 92, 035301 (2004)
Observation of a second-sound-like mode in superfluid-filled aerogel
International Nuclear Information System (INIS)
McKenna, M.J.; Slawecki, T.; Maynard, J.D.
1991-01-01
Superfluid 4 He is interesting acoustically because it can support more than one mode of sound propagation, and these can be used to study critical properties. Recently, there has been interest in superfluid-filled aerogels, but for such compressible materials one does not observe the ordinary (fourth) sound; instead there is a mode intermediate between first and fourth sound and a second-sound-like mode. We present a theory for the modes and the first observation of the aerogel second-sound-like mode, which is important because it propagates near the critical temperature
The path integral model of D-pairing for HTSC, heavy fermion superconductors, and superfluids
International Nuclear Information System (INIS)
Brusov, P.N.; Brusova, N.P.
1996-01-01
A model of d-pairing for superconducting and superfluid Fermi-systems has been formulated within the path integration technique. By path integration over open-quote fastclose quotes and open-quotes slowclose quotes Fermi-fields, the action functional (which determines all properties of model system) has been obtained. This functional could be used for the determination of different superconducting (superfluid) states, for calculation of the transition temperatures for these states, and for the calculation of the collective mode spectrum for HTSC, as well as for heavy fermion superconductors
Motions of quantized vortices attached to a boundary in alternating currents of superfluid 4He
International Nuclear Information System (INIS)
Yano, H.; Hashimoto, N.; Handa, A.; Obara, K.; Ishikawa, O.; Hata, T.; Nakagawa, M.
2007-01-01
The motions of superfluid vortices attached to a boundary are investigated in alternating currents by using a vibrating wire. The attached vortices appear to form a layer on the wire and enhance the mass of the wire, even for low velocity currents. In turbulence, chaotic motions of vortices such as entanglement and reconnection reduce the thickness of the layer in spite of the fact that the vortices unstably expand. When turbulence subsides, the attached vortices appear to shrink, with the degree of shrinking influenced by thermal excitations in the superfluid
The breakdown of superfluidity in liquid 4He
International Nuclear Information System (INIS)
Nancolas, G.G.; McClintock, P.V.E.; Bowley, R.M.
1985-01-01
The rate upsilon at which negative ions nucleate charged vortex rings in a series of extremely dilute superfluid 3 He/ 4 He solutions has been measured at a pressure of 23 bar over a temperature range (T) 0.33 - 0.61K, electric field range (E) 1.0 x 10 4 - 1.5 x 10 6 Vm -1 and an isotopic ratio range (x) ( 3 H/ 4 He) = 2.1 x 10 -8 - 1.7 x 10 -7 . The results are presented. A model is proposed which accounts for the behaviour of upsilon(E,T) in terms of changes in the average occupancy by 3 He atoms of trapping states on the surface of the ion if the nucleation rate ν 1 , due to ions each having one trapped 3 He atom, is very much greater than ν 0 for bare ions. The nonlinearities in ν(x 3 ) are interpreted in terms of the simultaneous trapping of two (or more) 3 He atoms on a significant fraction of the ions. The model can be fitted closely to the experimental data, yielding numerical values of ν 1 , of the 3 He binding energy on the ion, and of a number of other relevant quantities. The addition of a 3 He atom to a bare ion affects its propensity to create vortex rings by reducing the critical velocity for the process and by increasing the rate constant. The implications of these results for microscopic theories of the vortex nucleation mechanism are discussed. (U.K.)
Energy Technology Data Exchange (ETDEWEB)
Perraud, S
2007-12-15
This study aims at characterizing helium two phase flows, and to identify the dependence of their characteristics on various thermo-hydraulic parameters: vapour velocity, liquid height, vapour density, specificities of superfluidity. Both the engineer and the physicist's points of view are taken into consideration: the first one in terms of optimization of a particular cooling scheme based on a two-phase flow, and these second one in terms of more fundamental atomization-related questions. It has been shown that for velocities around 3 to 4 m/s, the liquid phase that was initially stratified undergoes an atomization through the presence of a drop haze carried by the vapor phase.This happens for superfluid helium as well as for normal helium without main differences on atomization.
Recent Spin Pump Experiments on Superfluid 3He-A1
Yamaguchi, A.; Kamada, N.; Motoyama, G.; Sumiyama, A.; Aoki, Y.; Okuda, Y.; Kubota, M.; Kojima, H.
2013-05-01
The superfluid 3He A1 phase, containing a spin-polarized condensate allows us to explore the dynamics of superfluid spin current. In the mechano-spin effect (MSE), a mechanically applied pressure gradient and a superleak-spin filter enable one to directly boost spin polarization of 3He in a small chamber. We are developing new apparatus for achieving greater enhancement of spin density. A development of a new-type 3He-hydraulic actuator has been already reported. We present here the construction of new-type of superleak-spin-filter made of packed powder aluminum oxide (referred as PAP-SL). The PAP-SL is popular in the study of superfluid 4He, but has not been established for that of the superfluid 3He. The attempt to construct the PAP-SL for the spin pump experiment was made by using aluminum oxide powder with nominal 1 μm powder diameter and with packing fraction of 40 %. Before executing the experiment, the nuclear demagnetization cryostat of ISSP, Univ. Tokyo which has been used for this experimental activity, was heavily damaged by the 2011 Great East Japan (Higashi Nihon) Earthquake. The repair work and earthquake damage protection strengthening has just been accomplished.
Effective action for superfluid Fermi systems in the strong-coupling limit
International Nuclear Information System (INIS)
Dupuis, N.
2005-01-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρ r and its conjugate variable, the phase θ r of the pairing order parameter Δ r . We recover the standard action of a Bose superfluid of density ρ r /2, where the bosons have a mass m B =2m and interact via a repulsive contact potential with amplitude g B =4πa B /m B ,a B =2a (a the s-wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude t B =J/2 and an on-site repulsive interaction U B =2Jz, where J=4t 2 /U (t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites)
Effective action for superfluid Fermi systems in the strong-coupling limit
Dupuis, N.
2005-07-01
We derive the low-energy effective action for three-dimensional superfluid Fermi systems in the strong-coupling limit, where superfluidity originates from Bose-Einstein condensation of composite bosons. Taking into account density and pairing fluctuations on the same footing, we show that the effective action involves only the fermion density ρr and its conjugate variable, the phase θr of the pairing order parameter Δr . We recover the standard action of a Bose superfluid of density ρr/2 , where the bosons have a mass mB=2m and interact via a repulsive contact potential with amplitude gB=4πaB/mB,aB=2a ( a the s -wave scattering length associated to the fermion-fermion interaction in vacuum). For lattice models, the derivation of the effective action is based on the mapping of the attractive Hubbard model onto the Heisenberg model in a uniform magnetic field, and a coherent state path integral representation of the partition function. The effective description of the Fermi superfluid in the strong-coupling limit is a Bose-Hubbard model with an intersite hopping amplitude tB=J/2 and an on-site repulsive interaction UB=2Jz , where J=4t2/U ( t and -U are the intersite hopping amplitude and the on-site attraction in the (fermionic) Hubbard model, z the number of nearest-neighbor sites).
Time-reversal-invariant topological superfluids in Bose-Fermi mixtures
DEFF Research Database (Denmark)
Midtgaard, Jonatan Melkaer; Wu, Zhigang; Bruun, G. M.
2017-01-01
A mixed dimensional system of fermions in two layers immersed in a Bose-Einstein condensate (BEC) is shown to be a promising setup to realize topological superfluids with time-reversal symmetry (TRS). The induced interaction between the fermions mediated by the BEC gives rise to a competition bet...
3 scientists win Nobel for physics electric superconductivity, superfluidity work honoured
2003-01-01
The Royal Swedish Academy of Sciences awarded the Nobel prize for physics to Russian Vitaly Ginzburg, 87, and Russian-born American Alexei Abrikosov, 75, for their work on electric superconductivity, and to British-born American Anthony Leggett, 65, for describing how liquid helium can become a "superfluid." The three scientists will split $1.3 million in prize money (1 page).
Long-wavelength phonons and the condensate in superfluid 4He
International Nuclear Information System (INIS)
Olinto, A.C.
1987-08-01
From Ward identities that take into account the condensate reservoir, the velocity of long-wavelength phonons is obtained as a function of the condensate fraction in the shielded potential approximation. The results are in good agreement with superfluid 4 He data. (Author) [pt
A vortex filament tracking method for the Gross–Pitaevskii model of a superfluid
International Nuclear Information System (INIS)
Villois, Alberto; Proment, Davide; Salman, Hayder; Krstulovic, Giorgio
2016-01-01
We present an accurate and robust numerical method to track quantised vortex lines in a superfluid described by the Gross–Pitaevskii equation. By utilising the pseudo-vorticity field of the associated complex scalar order parameter of the superfluid, we are able to track the topological defects of the superfluid and reconstruct the vortex lines which correspond to zeros of the field. Throughout, we assume our field is periodic to allow us to make extensive use of the Fourier representation of the field and its derivatives in order to retain spectral accuracy. We present several case studies to test the precision of the method which include the evaluation of the curvature and torsion of a torus vortex knot, and the measurement of the Kelvin wave spectrum of a vortex line and a vortex ring. The method we present makes no a priori assumptions on the geometry of the vortices and is therefore applicable to a wide range of systems such as a superfluid in a turbulent state that is characterised by many vortex rings coexisting with sound waves. This allows us to track the positions of the vortex filaments in a dense turbulent vortex tangle and extract statistical information about the distribution of the size of the vortex rings and the inter-vortex separations. In principle, the method can be extended to track similar topological defects arising in other physical systems. (paper)
Vortex flow in rotating superfluid .sup.3./sup.He-B
Czech Academy of Sciences Publication Activity Database
Skrbek, Ladislav; Blaauwgeers, R.; Eltsov, V. B.; Finne, A. P.; Kopnin, N. B.; Krusius, M.
329-333, - (2003), s. 106-107 ISSN 0921-4526 Institutional research plan: CEZ:AV0Z1010914 Keywords : superfluid 3 He * vortex dynamics * vortex formation * critical velocity * counterflow * magnus force * mutual friction Subject RIV: BK - Fluid Dynamics Impact factor: 0.908, year: 2003
Superfluidity of Bose-Einstein condensates in toroidal traps with nonlinear lattices
Czech Academy of Sciences Publication Activity Database
Yulin, A.V.; Bludov, Yu.V.; Konotop, V.V.; Kuzmiak, Vladimír; Salerno, M.
2011-01-01
Roč. 84, č. 6 (2011), 0636381-0636389 ISSN 1050-2947 R&D Projects: GA MŠk OC09060 Institutional research plan: CEZ:AV0Z20670512 Keywords : superfluidity * Bose -Einstein condensates * Josephson effect Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.878, year: 2011
Production of zero energy radioactive beams through extraction across superfluid helium surface
Takahashi, N; Huang, WX; Gloos, K; Dendooven, P; Pekola, JP; Aysto, J
A radioactive Ra-223 source was immersed in superfluid helium at 1.2-1.7 K. Electric fields transported recoiled Rn-219 ions in the form of snowballs to the surface and further extracted them across the surface. The ions were focussed onto an aluminium foil and alpha particle spectra were taken with
Dipole modes of a superfluid Bose–Fermi mixture in the BCS-BEC crossover
International Nuclear Information System (INIS)
Wen, Wen; Chen, Bingyan; Zhang, Xuewu
2017-01-01
Motivated by the first experimental realization by the Ecole Normale Supérieure (ENS) group of a mixture of a Bose–Einstein condensate with a Fermi superfluid continuously changing from a Bardeen–Cooper–Schrieffer (BCS) superfluid to a Bose–Einstein condensate (BEC) (Ferrier-Barbut et al 2014 Science 345 1035), we analytically study the dipole modes of the superfluid Bose–Fermi mixture in the BCS-BEC crossover. The analytical approach can explicitly reveal relationships between the frequencies of the dipole modes and the microscopic properties of the novel system. We start from coupled hydrodynamic equations, where the equation of state for the Fermi superfluid in the crossover is an analytical fitting formula based on experimental data, and by using a scaling approach we analytically study eigenfrequencies of the dipole modes for the coupled system in the ENS experimental parameters. Without the boson–fermion interaction in the equilibrium density profiles, our theoretical results can be reduced to the mean-field model and is consistent with the experimental data. However, by further taking into account the boson–fermion interaction numerically and analytically, we find that the results disagree with the experiment, especially in the parameter regime where the boson interaction is smaller than the boson–fermion interaction. (paper)
d-wave superfluid with gapless edges in a cold-atom trap
DEFF Research Database (Denmark)
Larsen, Anne-Louise Gadsbølle; Francis Song, H.; Le Hur, Karyn
2012-01-01
and competing phases. In particular, at low temperatures, this allows the realization of a d-wave superfluid region surrounded by purely (gapless) normal edges. Solving the Bogoliubov–de Gennes equations and comparing them with the local density approximation, we show that the proximity to the Mott insulator...
Film thinning in unsaturated superfluid 4He films during persistent flow
International Nuclear Information System (INIS)
Ekholm, D.T.; Hallock, R.B.
1979-01-01
We report measurements of the thickness of unsaturated superfluid 4 He films in persistent flow as a function of persistent current velocity. Our results are in quantitative agreement with the predictions of Kontorovich, and thus disagree with the conclusion of Rudnick and coworkers that rho/sub s//rho has an enhanced velocity dependence in these films
Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances
He, Lianyi; Hu, Hui; Liu, Xia-Ji
2018-01-01
We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of K 40 or Li 6 atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity, and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.
Coexistence of density wave and superfluid order in a dipolar Fermi gas
DEFF Research Database (Denmark)
Wu, Zhigang; Block, Jens Kusk; Bruun, Georg M.
2015-01-01
We analyse the coexistence of superfluid and density wave (stripe) order in a quasi-two-dimensional gas of dipolar fermions aligned by an external field. Remarkably, the anisotropic nature of the dipolar interaction allows for such a coexistence in a large region of the zero temperature phase...
Decay of superfluid currents in the interacting one-dimensional Bose gas
Cherny, A.Y.; Caux, J.S.; Brand, J.
2009-01-01
We examine the superfluid properties of a one-dimensional (1D) Bose gas in a ring trap based on the model of Lieb and Liniger. While the 1D Bose gas has nonclassical rotational inertia and exhibits quantization of velocities, the metastability of currents depends sensitively on the strength of
Theory of superfluidity and drag force in the one-dimensional Bose gas
Cherny, A.Y.; Caux, J.-S.; Brand, J.
2012-01-01
The one-dimensional Bose gas is an unusual superfluid. In contrast to higher spatial dimensions, the existence of non-classical rotational inertia is not directly linked to the dissipationless motion of infinitesimal impurities. Recently, experimental tests with ultracold atoms have begun and
Disproportionate entrance length in superfluid flows and the puzzle of counterflow instabilities
Bertolaccini, J.; Lévêque, E.; Roche, P.-E.
2017-12-01
Systematic simulations of the two-fluid model of superfluid helium (He-II) encompassing the Hall-Vinen-Bekharevich-Khalatnikov (HVBK) mutual coupling have been performed in two-dimensional pipe counterflows between 1.3 and 1.96 K. The numerical scheme relies on the lattice Boltzmann method. A Boussinesq-like hypothesis is introduced to omit temperature variations along the pipe. In return, the thermomechanical forcings of the normal and superfuid components are fueled by a pressure term related to their mass-density variations under an approximation of weak compressibility. This modeling framework reproduces the essential features of a thermally driven counterflow. A generalized definition of the entrance length is introduced to suitably compare entry effects (of different nature) at opposite ends of the pipe. This definition is related to the excess of pressure loss with respect to the developed Poiseuille-flow solution. At the heated end of the pipe, it is found that the entrance length for the normal fluid follows a classical law and increases linearly with the Reynolds number. At the cooled end, the entrance length for the superfluid is enhanced as compared to the normal fluid by up to one order of magnitude. At this end, the normal fluid flows into the cooling bath of He-II and produces large-scale superfluid vortical motions in the bath that partly re-enter the pipe along its sidewalls before being damped by mutual friction. In the superfluid entry region, the resulting frictional coupling in the superfluid boundary layer distorts the velocity profiles toward tail flattening for the normal fluid and tail raising for the superfluid. Eventually, a simple analytical model of entry effects allows us to re-examine the long-debated thresholds of T 1 and T 2 instabilities in superfluid counterflows. Inconsistencies in the T 1 thresholds reported since the 1960s disappear if an aspect-ratio criterion based on our modeling is used to discard data sets with the
Electron Bubbles in Superfluid (3) 3 He-A: Exploring the Quasiparticle-Ion Interaction
Shevtsov, Oleksii; Sauls, J. A.
2017-06-01
When an electron is forced into liquid ^3He, it forms an "electron bubble", a heavy ion with radius, R˜eq 1.5 nm, and mass, M˜eq 100 m_3, where m_3 is the mass of a ^3He atom. These negative ions have proven to be powerful local probes of the physical properties of the host quantum fluid, especially the excitation spectra of the superfluid phases. We recently developed a theory for Bogoliubov quasiparticles scattering off electron bubbles embedded in a chiral superfluid that provides a detailed understanding of the spectrum of Weyl Fermions bound to the negative ion, as well as a theory for the forces on moving electron bubbles in superfluid ^3He-A (Shevtsov and Sauls in Phys Rev B 94:064511, 2016). This theory is shown to provide quantitative agreement with measurements reported by the RIKEN group (Ikegami et al. in Science 341(6141):59, 2013) for the drag force and anomalous Hall effect of moving electron bubbles in superfluid ^3He-A. In this report, we discuss the sensitivity of the forces on the moving ion to the effective interaction between normal-state quasiparticles and the ion. We consider models for the quasiparticle-ion (QP-ion) interaction, including the hard-sphere potential, constrained random-phase-shifts, and interactions with short-range repulsion and intermediate-range attraction. Our results show that the transverse force responsible for the anomalous Hall effect is particularly sensitive to the structure of the QP-ion potential and that strong short-range repulsion, captured by the hard-sphere potential, provides an accurate model for computing the forces acting on the moving electron bubble in superfluid 3He-A.
Czech Academy of Sciences Publication Activity Database
La Mantia, M.; Chagovets, Tymofiy; Rotter, M.; Skrbek, L.
2012-01-01
Roč. 83, č. 5 (2012), "055109-1"-"055109-8" ISSN 0034-6748 Grant - others:GA ČR(CZ) GAP203/11/0442; EU COST(XE) MP0806 Institutional research plan: CEZ:AV0Z10100520 Keywords : tracer particles * piv * superfluid helium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.602, year: 2012
Watanabe, Gentaro; Pethick, C J
2017-08-11
Calculations of the effects of band structure on the neutron superfluid density in the crust of neutron stars made under the assumption that the effects of pairing are small [N. Chamel, Phys. Rev. C 85, 035801 (2012)PRVCAN0556-2813] lead to moments of inertia of superfluid neutrons so small that the crust alone is insufficient to account for the magnitude of neutron star glitches. Inspired by earlier work on ultracold atomic gases in an optical lattice, we investigate fermions with attractive interactions in a periodic lattice in the mean-field approximation. The effects of band structure are suppressed when the pairing gap is of order or greater than the strength of the lattice potential. By applying the results to the inner crust of neutron stars, we conclude that the reduction of the neutron superfluid density is considerably less than previously estimated and, consequently, it is premature to rule out models of glitches based on neutron superfluidity in the crust.
International Nuclear Information System (INIS)
Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Fujita, Tomomi; Imamura, Kei; Yamaguchi, Yasuhiro; Tetsuka, Hiroki; Tsutsui, Yoshiki; Mitsuya, Yosuke; Ichikawa, Yuichi; Ishibashi, Yoko; Yoshida, Naoki; Shirai, Hazuki; Ebara, Yuta; Hayasaka, Miki; Arai, Shino; Muramoto, Sosuke
2013-01-01
Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the 85 Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a 85 Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the 85 Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Lubkin, G.B. [American Institute of Physics, 500 Sunnyside Boulevard, Woodbury, New York 11797 (United States)
1996-12-01
A quarter of a century ago three Cornell experimenters found that when they cooled {sup 3}He below 3 mK it had three different superfluid phases and behaved anisotropically. {copyright} {ital 1996 American Institute of Physics.}
Energy Technology Data Exchange (ETDEWEB)
Furukawa, Takeshi, E-mail: takeshi@tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakui, Takashi [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai, Miyagi 980-8578 (Japan); Yang, Xiaofei [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); School of Physics, Peking University, Chengfu Road, Haidian District, Beijing 100871 (China); Fujita, Tomomi [Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Imamura, Kei; Yamaguchi, Yasuhiro [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Tetsuka, Hiroki; Tsutsui, Yoshiki [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501,Japan (Japan); Mitsuya, Yosuke [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Ichikawa, Yuichi [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ishibashi, Yoko [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Yoshida, Naoki; Shirai, Hazuki [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ebara, Yuta; Hayasaka, Miki [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501,Japan (Japan); Arai, Shino; Muramoto, Sosuke [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); and others
2013-12-15
Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the {sup 85}Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a {sup 85}Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the {sup 85}Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei.
Superfluid density and quasi-long-range order in the one-dimensional disordered Bose-Hubbard model
Gerster, M.; Rizzi, M.; Tschirsich, F.; Silvi, P.; Fazio, R.; Montangero, S.
2016-01-01
We study the equilibrium properties of the one-dimensional disordered Bose-Hubbard model by means of a gauge-adaptive tree tensor network variational method suitable for systems with periodic boundary conditions. We compute the superfluid stiffness and superfluid correlations close to the superfluid to glass transition line, obtaining accurate locations of the critical points. By studying the statistics of the exponent of the power-law decay of the correlation, we determine the boundary between the superfluid region and the Bose glass phase in the regime of strong disorder and in the weakly interacting region, not explored numerically before. In the former case our simulations are in agreement with previous Monte Carlo calculations.
Kurkcuoglu, Doga Murat; Sá de Melo, C. A. R.
2018-02-01
We describe how color superfluidity is modified in the presence of color-flip and color-orbit fields in the context of ultracold atoms and discuss connections between this problem and that of color superconductivity in quantum chromodynamics. We study the case of s -wave contact interactions between different colors and we identify several superfluid phases, with five being nodal and one being fully gapped. When our system is described in a mixed-color basis, the superfluid order parameter tensor is characterized by six independent components with explicit momentum dependence induced by color-orbit coupling. The nodal superfluid phases are topological in nature and the low-temperature phase diagram of the color-flip field versus the interaction parameter exhibits a pentacritical point, where all five nodal color superfluid phases converge. These results are in sharp contrast to the case of zero color-flip and color-orbit fields, where the system has perfect U(3) symmetry and possesses a superfluid phase that is characterized by fully gapped quasiparticle excitations with a single complex order parameter with no momentum dependence and by inert unpaired fermions representing a nonsuperfluid component. In the latter case, just a crossover between a Bardeen-Cooper-Schrieffer and a Bose-Einstein-condensation superfluid occurs. Furthermore, we analyze the order parameter tensor in a total pseudospin basis, investigate its momentum dependence in the singlet, triplet, and quintet sectors, and compare the results with the simpler case of spin-1/2 fermions in the presence of spin-flip and spin-orbit fields, where only singlet and triplet channels arise. Finally, we analyze in detail spectroscopic properties of color superfluids in the presence of color-flip and color-orbit fields, such as the quasiparticle excitation spectrum, momentum distribution, and density of states to help characterize all the encountered topological quantum phases, which can be realized in fermionic
An, Taeyang; Cha, Min-Chul
2013-03-01
We study the superfluid-insulator quantum phase transition in a disordered two-dimensional quantum rotor model with random on-site interactions in the presence of particle-hole symmetry. Via worm-algorithm Monte Carlo calculations of superfluid density and compressibility, we find the dynamical critical exponent z ~ 1 . 13 (2) and the correlation length critical exponent 1 / ν ~ 1 . 1 (1) . These exponents suggest that the insulating phase is a incompressible Mott glass rather than a Bose glass.
Energy Technology Data Exchange (ETDEWEB)
Premke, Tobias
2016-02-19
Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the
Han, Li; Sa de Melo, Carlos
2013-03-01
We discuss the evolution from BCS to Bose superfluidity for ultracold fermions in two-dimensions and in the presence of simultaneous spin-orbit and Zeeman fields. We analyze several thermodynamic properties to characterize different superfluid phases including pressure, compressibility, induced polarization, and spin susceptibility. Furthermore, we compute the momentum distribution and construct topological invariants for each of the superfluid phases. We thank ARO (Contract No. W911NF-09-1-0220) for support.
Dynamics of normal and superfluid fogs using diffusing-wave spectroscopy
International Nuclear Information System (INIS)
Kim, Heetae; Lemieux, Pierre-Anthony; Durian, Douglas J.; Williams, Gary A.
2004-01-01
The dynamics of normal and superfluid fogs are studied using the technique of diffusing-wave spectroscopy. For a water fog generated with a 1.75 MHz piezoelectric driver below the liquid surface, the 7 μm diameter droplets are found to have diffusive dynamics for correlation times long compared to the viscous time. For a fog of 10 μm diameter superfluid helium droplets in helium vapor at 1.5 K the motion appears to be ballistic for correlation times short compared to the viscous time. The velocity correlations between the helium droplets are found to depend on the initial velocity with which the droplets are injected from the helium surface into the fog
International Nuclear Information System (INIS)
Chernobaj, V.A.; Andronik, V.V.
1978-01-01
The necessity of taking into account the relativistic effects in quantized vortices of pulsar superfluid nuclei is shown. The full energy of a single vortex for special relativity theory approximation is determined. The single vortex full energy asymptotics for quantized numbers n, which are much greater than the ratio of vortex exterior radius to Compton's length of the nucleon, wave is linear with respect to n while in the nonrelativistic case the kinetic energy is proportional to n 2 . This suggests the possibility of existence of quasistable vortices with great quantized numbers n. It is revealed that for small quantized numbers the taking into account of the relativistic effects in the vortices does not lead to qualitative changes of the general condition of superfluid liquid rotation as compared to non-relativistic theory
Superfluid density and heat capacity measurements of 4He in porous gold
International Nuclear Information System (INIS)
Yoon, J.; Chan, M.
1995-01-01
Superfluid density of full pore 4 He as well as thin film 4 He confined in porous gold were measured as a function of temperature. The superfluid transition temperature of full pore was found to be 2.156 K. In both cases power law dependence on reduced temperature was found and the exponent was found to be the same as that of bulk 4 He. Porous gold is made by electrochemically leaching out silver from silver-gold alloy. The porous gold sample the authors fabricated has porosity of 55 with a diameter of 250 angstrom. Electron microscope picture shows that the structure of porous gold is exceedingly similar to that of Vycor. Heat capacity measurement of full pore 4 He in porous gold is in progress
Thermal studies of a high gradient quadrupole magnet cooled with pressurized, stagnant superfluid
Chiesa, L; Kerby, J S; Lamm, M J; Novitski, I; Orris, D; Ozelis, J P; Peterson, Thomas J; Tartaglia, M; Zlobin, A V
2001-01-01
A 2-m long superconducting model of an LHC Interaction Region quadrupole magnet was wound with stabrite coated cable. The resulting low interstrand resistance and high AC losses presented the opportunity to measure magnet quench performance in superfluid as a function of helium temperature and heat deposition in the coil. Our motivation was to duplicate the high radiation heat loads predicted for the inner triplet quadrupoles at LHC and study the coil cooling conditions in the magnet. At the Magnet Test Facility in Fermilab's Technical Division, the magnet quench performance was tested as a function of bulk helium temperature and current ramp rate near the planned high luminosity interaction region field gradient of 205 T/m. AC loss measurements provided a correlation between current ramp rate and heat deposition in the coil. Analysis indicates that the results are consistent with there being little participation of superfluid helium in the small channels inside the inner layer in the heat removal from the co...
Observation of Intrinsic Magnus Force and Direct Detection of Chirality in Superfluid 3He-A
Ikegami, Hiroki; Tsutsumi, Yasumasa; Kono, Kimitoshi
2015-04-01
We report details of the observation of the intrinsic Magnus (IM) force acting on negative and positive ions trapped just below a free surface of the A phase of superfluid 3He (3He-A). From the transport measurements of the ions along the surface, we found that the IM force acts on both the negative and positive ions. We also demonstrate that the transport measurements could distinguish whether the surface is composed of a chiral monodomain or multiple chiral domains. For multiple chiral domains, the current of the ions was found to be irreproducible and unstable, which was reasonably explained by the formation of the chiral domain structure and the dynamics of the chiral domain walls. For chiral monodomains, the appearance ratio of chirality emerging upon cooling through the superfluid transition temperature was found to depend on the direction of the external magnetic field, which implies the existence of an unknown coupling between the chirality and the magnetic field.
Velocity statistics in holographic fluids: magnetized quark-gluon plasma and superfluid flow
Energy Technology Data Exchange (ETDEWEB)
Areán, Daniel [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805, Munich (Germany); Zayas, Leopoldo A. Pando [The Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, 34014 Trieste (Italy); Michigan Center for Theoretical Physics, Department of Physics, University of Michigan,450 Church Street, Ann Arbor, MI 48109 (United States); Patiño, Leonardo; Villasante, Mario [Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México,A.P. 70-542, México D.F. 04510 (Mexico)
2016-10-28
We study the velocity statistics distribution of an external heavy particle in holographic fluids. We argue that when the dual supergravity background has a finite temperature horizon the velocity statistics goes generically as 1/v, compatible with the jet-quenching intuition from the quark-gluon plasma. A careful analysis of the behavior of the classical string whose apparent world sheet horizon deviates from the background horizon reveals that other regimes are possible. We numerically discuss two cases: the magnetized quark-gluon plasma and a model of superfluid flow. We explore a range of parameters in these top-down supergravity solutions including, respectively, the magnetic field and the superfluid velocity. We determine that the velocity statistics goes largely as 1/v, however, as we leave the non-relativistic regime we observe some deviations.
Boyack, Rufus; Wu, Chien-Te; Anderson, Brandon M.; Levin, K.
2017-06-01
In this paper we demonstrate the necessity of including the generally omitted collective-mode contributions in calculations of the Meissner effect for nonuniform superconductors. We consider superconducting pairing with nonzero center-of-mass momentum, as is possibly relevant to high transition temperature cuprates, cold atoms, and color superconductors in quantum chromodynamics. For the concrete example of the Fulde-Ferrell phase we present a quantitative calculation of the superfluid density, showing not only that the collective-mode contributions are appreciable but also that they derive from the amplitude mode of the order parameter. This latter mode is generally viewed as being invisible in conventional superconductors. However, our analysis shows that it is extremely important in pair-density-wave-type superconductors, where it destroys stable superfluidity well before the mean-field order parameter vanishes.
Rapid Cooling of the Neutron Star in Cassiopeia A Triggered by Neutron Superfluidity in Dense Matter
International Nuclear Information System (INIS)
Page, Dany; Prakash, Madappa; Lattimer, James M.; Steiner, Andrew W.
2011-01-01
We propose that the observed cooling of the neutron star in Cassiopeia A is due to enhanced neutrino emission from the recent onset of the breaking and formation of neutron Cooper pairs in the 3 P 2 channel. We find that the critical temperature for this superfluid transition is ≅0.5x10 9 K. The observed rapidity of the cooling implies that protons were already in a superconducting state with a larger critical temperature. This is the first direct evidence that superfluidity and superconductivity occur at supranuclear densities within neutron stars. Our prediction that this cooling will continue for several decades at the present rate can be tested by continuous monitoring of this neutron star.
Non-Radial Oscillation Modes of Superfluid Neutron Stars Modeled with CompOSE
Directory of Open Access Journals (Sweden)
Prashanth Jaikumar
2018-03-01
Full Text Available We compute the principal non-radial oscillation mode frequencies of Neutron Stars described with a Skyrme-like Equation of State (EoS, taking into account the possibility of neutron and proton superfluidity. Using the CompOSE database and interpolation routines to obtain the needed thermodynamic quantities, we solve the fluid oscillation equations numerically in the background of a fully relativistic star, and identify imprints of the superfluid state. Though these modes cannot be observed with current technology, increased sensitivity of future Gravitational-Wave Observatories could allow us to observe these oscillations and potentially constrain or refine models of dense matter relevant to the interior of neutron stars.
Subgap in the Surface Bound States Spectrum of Superfluid ^3 He-B with Rough Surface
Nagato, Y.; Higashitani, S.; Nagai, K.
2017-12-01
The subgap structure in the surface bound states spectrum of superfluid ^3 He-B with rough surface is discussed. The subgap is formed by the level repulsion between the surface bound state and the continuum states in the course of multiple scattering by the surface roughness. We show that the level repulsion is originated from the nature of the wave function of the surface bound state that is now recognized as Majorana fermion. We study the superfluid ^3 He-B with a rough surface and in a magnetic field perpendicular to the surface using the quasi-classical Green function together with a random S-matrix model. We calculate the self-consistent order parameters, the spin polarization density and the surface density of states. It is shown that the subgap is found also in a magnetic field perpendicular to the surface. The magnetic field dependence of the transverse acoustic impedance is also discussed.
Asymptotic exactness of c-number substitution in Bogolyubov's theory of superfluidity
Directory of Open Access Journals (Sweden)
N.N. Bogolyubov, Jr.
2010-01-01
Full Text Available The Bogolyubov model of liquid helium is considered. The validity of substituting a c-number for the k=0 mode operator â0 is established rigorously. The domain of stability of the Bogolyubov's Hamiltonian is found. We derive sufficient conditions which ensure the appearance of the Bose condensate in the model. For some temperatures and some positive values of the chemical potential, there is a gapless Bogolyubov spectrum of elementary excitations, leading to a proper microscopic interpretation of superfluidity.
Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels
Directory of Open Access Journals (Sweden)
Saluto Lidia
2016-06-01
Full Text Available We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-order terms obtained from dimensional analysis or other physical arguments.
Self-consistent quasi-particle RPA for the description of superfluid Fermi systems
Rahbi, A; Chanfray, G; Schuck, P
2002-01-01
Self-Consistent Quasi-Particle RPA (SCQRPA) is for the first time applied to a more level pairing case. Various filling situation and values for the coupling constant are considered. Very encouraging results in comparison with the exact solution of the model are obtaining. The nature of the low lying mode in SCQRPA is identified. The strong reduction of the number fluctuation in SCQRPA vs BCS is pointed out. The transition from superfluidity to the normal fluid case is carefully investigated.
Energy Technology Data Exchange (ETDEWEB)
Imamura, Kei, E-mail: kimamura@riken.jp [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Furukawa, Takeshi [Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Wakui, Takashi [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aoba, Aramaki, Aoba, Sendai, Miyagi 980-8578 (Japan); Yang, Xiaofei [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); School of Physics, Peking University, Chengfu Road, Haidian District, Beijing 100871 (China); Yamaguchi, Yasuhiro [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Tetsuka, Hiroki [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Mitsuya, Yosuke [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Tsutsui, Yoshiki [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Fujita, Tomomi [Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Ebara, Yuta; Hayasaka, Miki [Department of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Arai, Shino; Muramoto, Sosuke [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama, Kawasaki, Kanagawa 214-8571 (Japan); Ichikawa, Yuichi [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, Tokyo Instutute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan); Ishibashi, Yoko [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); and others
2013-12-15
We are developing a new nuclear laser spectroscopic technique for the study of nuclear structure that can be applied to short-lived low-yield atoms with unstable nuclei. The method utilizes superfluid helium (He II) as a trapping medium for high-energy ion beams. A liquid helium cryostat with optical windows is a key apparatus for this type of experiment. We describe the design and the performance of the cryostat which is developed for the present project.
Experiments on the attenuation of third sound in saturated superfluid helium films
International Nuclear Information System (INIS)
Telschow, K.L.; Galkiewicz, R.K.; Hallock, R.B.
1976-01-01
Upper limits of the attenuation of third sound in saturated superfluid 4 He films have been measured in three separate experiments. Observations at frequencies from 0.1 to 200 Hz indicate that the attenuation in these thick films is substantially lower than would be inferred from the only previous experiment done on saturated films. The third-sound velocity is observed to have the temperature dependence predicted by Bergman
Faraday waves in quasi-one-dimensional superfluid Fermi-Bose mixtures
DEFF Research Database (Denmark)
Abdullaev, F. Kh.; Ögren, Magnus; Sørensen, Mads Peter
2013-01-01
The generation of Faraday waves in superfluid Fermi-Bose mixtures in elongated traps is investigated. The generation of waves is achieved by periodically changing a parameter of the system in time. Two types of modulations of parameters are considered: a variation of the fermion-boson scattering...... length and the boson-boson scattering length. We predict the properties of the generated Faraday patterns and study the parameter regions where they can be excited....
Inhomogeneous vortex tangles in counterflow superfluid turbulence: flow in convergent channels
Saluto, L.; Mongiovi', M.
2016-01-01
We investigate the evolution equation for the average vortex length per unit volume L of superfluid turbulence in inhomogeneous flows. Inhomogeneities in line density L andincounterflowvelocity V may contribute to vortex diffusion, vortex formation and vortex destruction. We explore two different families of contributions: those arising from asecondorder expansionofthe Vinenequationitself, andthose whichare notrelated to the original Vinen equation but must be stated by adding to it second-or...
Multiple-scale approach for the expansion scaling of superfluid quantum gases
Egusquiza, I. L.; Modugno, M.; Basagoiti, M. A. Valle
2011-01-01
We present a general method, based on a multiple-scale approach, for deriving the perturbative solutions of the scaling equations governing the expansion of superfluid ultracold quantum gases released from elongated harmonic traps. We discuss how to treat the secular terms appearing in the usual naive expansion in the trap asymmetry parameter epsilon, and calculate the next-to-leading correction for the asymptotic aspect ratio, with significant improvement over the previous proposals.
International Nuclear Information System (INIS)
Anderson, C.R.
2000-01-01
We present neutron inelastic scattering measurements of the low energy excitations of superfluid 4 He. Measurements on three types of superfluid system have been taken: Bulk superfluid, superfluid in the presence of static disorder ( 4 He confined in porous glasses) and superfluid in the presence of dynamic disorder (dilute 3 He- 4 He mixtures). For the bulk liquid, we find that the temperature dependence of the roton may be described well by the generally accepted BPZ theory [Bedell 1984], over the temperature region 0.4-1.8 K. However we also find our results to be in agreement with the high-resolution measurements of Andersen et al who reported a deviation from the BPZ theory at temperatures below 1 K [Andersen 1996]. We find that the energy of the maxon does surpass that of two times the roton energy at elevated pressure. This result cannot be explained simply from a theoretical point of view and we offer an explanation in terms of a hybridisation between the single particle excitation and the two-roton continuum. A high-resolution study of the roton when the superfluid is confined in porous aerogel glass shows the excitation to remain sharp down to temperatures of 0.07 K. This result contradicts the results of previous studies [Gibbs 1997, Plantevin 1998] who found that the roton exhibited an anomalous linewidth at low temperatures. We present the first successful neutron scattering measurements of the superfluid confined in porous Vycor and xerogel glasses. We observe a sharp excitation with a dispersion almost identical to that of the phonon-roton excitation of the bulk liquid. We also observe extra scattering at energies below that of the bulk-like excitation. This scattering has been attributed to two-dimensional layer excitations previously only observed in neutron scattering studies of thin films of the superfluid adsorbed onto various forms of graphite substrate. High resolution studies of S(Q,ω) of a 1% mixture of 3 He in superfluid 4 He reveals no
Microscopic dynamics and velocity profiles of bacterial superfluids under oscillatory shear
Cheng, Xiang; Guo, Shuo; Samanta, Devranjan; Peng, Yi; Xu, Xinliang
Bacterial suspensions a premier example of active fluids show an unusual response to shear stresses. Rather than increasing the viscosity of the suspending fluid, swimming bacteria can self-organize into collective flows under shear, turning the suspension into a ``superfluid'' with zero apparent viscosity. Although the existence of the bacterial superfluid has been demonstrated in bulk rheology measurements, little is known about the microscopic dynamics of such an exotic phase. Here, by combining sensitive rheology measurements with high-speed confocal microscopy, we study the detailed 3D dynamics of concentrated bacterial suspensions confined in narrow gaps under oscillatory shear. We find that sheared bacterial suspensions in the superfluidic phase exhibit velocity profiles with strong spatial heterogeneity, unexpected from the established hydrodynamic theory of active fluids. We quantitatively explain the observed velocity profiles by considering a balance of active stresses and shear stresses in an ensemble average. Our experiments reveal a profound influence of shear flows on bacterial locomotion and provide new insights to the origin of the unique flow behaviors of active fluids.
He, Yan; Guo, Hao
2016-07-01
Respecting the conservation laws of momentum and energy in a many body theory is very important for understanding the transport phenomena. The previous conserving approximation requires that the self-energy of a single particle could be written as a functional derivative of a full dressed Green's function. This condition can not be satisfied in the G0 G t-matrix or pair fluctuation theory which emphasizes the fermion pairing with a stronger than the Bardeen-Cooper-Schrieffer (BCS) attraction. In the previous work [1], we have shown that when the temperature is above the superfluid transition temperature Tc, the G0 G t-matrix theory can be put into a form that satisfies the stress tensor Ward identity (WI) or local form of conservation laws by introducing a new type of vertex correction. In this paper, we will extend the above conservation approximation to the superfluid phase in the BCS mean field level. To establish the stress tensor WI, we have to include the fluctuation of the order parameter or the contribution from the Goldstone mode. The result will be useful for understanding the transport properties such as the behavior of the viscosity of Fermionic gases in the superfluid phases.
Coupling an Ensemble of Electrons on Superfluid Helium to a Superconducting Circuit
Directory of Open Access Journals (Sweden)
Ge Yang
2016-03-01
Full Text Available The quantized lateral motional states and the spin states of electrons trapped on the surface of superfluid helium have been proposed as basic building blocks of a scalable quantum computer. Circuit quantum electrodynamics allows strong dipole coupling between electrons and a high-Q superconducting microwave resonator, enabling such sensitive detection and manipulation of electron degrees of freedom. Here, we present the first realization of a hybrid circuit in which a large number of electrons are trapped on the surface of superfluid helium inside a coplanar waveguide resonator. The high finesse of the resonator allows us to observe large dispersive shifts that are many times the linewidth and make fast and sensitive measurements on the collective vibrational modes of the electron ensemble, as well as the superfluid helium film underneath. Furthermore, a large ensemble coupling is observed in the dispersive regime during experiment, and it shows excellent agreement with our numeric model. The coupling strength of the ensemble to the cavity is found to be ≈1 MHz per electron, indicating the feasibility of achieving single electron strong coupling.
Collignon, Clément; Fauqué, Benoît; Cavanna, Antonella; Gennser, Ulf; Mailly, Dominique; Behnia, Kamran
2017-12-01
We present a study of the lower critical field, Hc 1, of SrTi1 -xNbxO3 as a function of carrier concentration with the aim of quantifying the superfluid density. At low carrier concentration (i.e., the underdoped side), superfluid density and the carrier concentration in the normal state are equal within experimental margin. A significant deviation between the two numbers starts at optimal doping and gradually increases with doping. The inverse of the penetration depth and the critical temperature follow parallel evolutions as in the case of cuprate superconductors. In the overdoped regime, the zero-temperature superfluid density becomes much lower than the normal-state carrier density before vanishing all together. We show that the density mismatch and the clean-to-dirty crossover are concomitant. Our results imply that the discrepancy between normal and superconducting densities is expected whenever the superconducting gap becomes small enough to put the system in the dirty limit. A quantitative test of the dirty BCS theory is not straightforward, due to the multiplicity of the bands in superconducting strontium titanate.
Zhang, Jie; He, Yunteng; Lei, Lei; Alghamdi, Maha; Oswalt, Andrew; Kong, Wei
2017-08-01
In an effort to solve the crystallization problem in crystallography, we have been engaged in developing a method termed "serial single molecule electron diffraction imaging" (SS-EDI). The unique features of SS-EDI are superfluid helium droplet cooling and field-induced orientation: together the two features constitute a molecular goniometer. Unfortunately, the helium atoms surrounding the sample molecule also contribute to a diffraction background. In this report, we analyze the properties of a superfluid helium droplet beam and its doping statistics, and demonstrate the feasibility of overcoming the background issue by using the velocity slip phenomenon of a pulsed droplet beam. Electron diffraction profiles and pair correlation functions of ferrocene-monomer-doped droplets and iodine-nanocluster-doped droplets are presented. The timing of the pulsed electron gun and the effective doping efficiency under different dopant pressures can both be controlled for size selection. This work clears any doubt of the effectiveness of superfluid helium droplets in SS-EDI, thereby advancing the effort in demonstrating the "proof-of-concept" one step further.
A Superfluid Pulse Tube Refrigerator Without Moving Parts for Sub-Kelvin Cooling
Miller, Franklin K.
2012-01-01
A report describes a pulse tube refrigerator that uses a mixture of He-3 and superfluid He-4 to cool to temperatures below 300 mK, while rejecting heat at temperatures up to 1.7 K. The refrigerator is driven by a novel thermodynamically reversible pump that is capable of pumping the He-3 He-4 mixture without the need for moving parts. The refrigerator consists of a reversible thermal magnetic pump module, two warm heat exchangers, a recuperative heat exchanger, two cold heat exchangers, two pulse tubes, and an orifice. It is two superfluid pulse tubes that run 180 out of phase. All components of this machine except the reversible thermal pump have been demonstrated at least as proof-of-concept physical models in previous superfluid Stirling cycle machines. The pump consists of two canisters packed with pieces of gadolinium gallium garnet (GGG). The canisters are connected by a superleak (a porous piece of VYCOR glass). A superconducting magnetic coil surrounds each of the canisters.
Control of the wetting properties of ^{4}He crystals in superfluid.
Takahashi, T; Minezaki, H; Suzuki, A; Obara, K; Itaka, K; Nomura, R; Okuda, Y
2016-05-01
To investigate whether it is possible to control the wetting of ^{4}He crystals on a wall in superfluid, the contact angles of ^{4}He crystals were measured on rough and smooth walls at very low temperatures. A rough wall was prepared in a simple manner in which a commercially available coating agent for car mirrors, which makes the glass surface superhydrophobic, was used to coat a glass plate. The contact angles of ^{4}He crystals were increased by approximately 10^{∘} on the rough wall coated with the agent. Therefore, the increase in the repellency of ^{4}He crystals in superfluid was demonstrated to be possible on a very rough surface. The enhancement of the contact angles and a scanning electron microscopy image of the coated surface both suggest that a Cassie-Baxter state of ^{4}He crystals was realized on the surface; the crystals did not have full contact with the wall, but entrapped superfluid was present beneath the crystals in the hollow parts of the rough wall.
Stability of superfluid phases in the 2D spin-polarized attractive Hubbard model
Kujawa-Cichy, A.; Micnas, R.
2011-08-01
We study the evolution from the weak coupling (BCS-like limit) to the strong coupling limit of tightly bound local pairs (LPs) with increasing attraction, in the presence of the Zeeman magnetic field (h) for d=2, within the spin-polarized attractive Hubbard model. The broken symmetry Hartree approximation as well as the strong coupling expansion are used. We also apply the Kosterlitz-Thouless (KT) scenario to determine the phase coherence temperatures. For spin-independent hopping integrals (t↑=t↓), we find no stable homogeneous polarized superfluid (SCM) state in the ground state for the strong attraction and obtain that for a two-component Fermi system on a 2D lattice with population imbalance, phase separation (PS) is favoured for a fixed particle concentration, even on the LP (BEC) side. We also examine the influence of spin-dependent hopping integrals (mass imbalance) on the stability of the SCM phase. We find a topological quantum phase transition (Lifshitz type) from the unpolarized superfluid phase (SC0) to SCM and tricritical points in the h-|U| and t↑/t↓-|U| ground-state phase diagrams. We also construct the finite temperature phase diagrams for both t↑=t↓ and t↑≠t↓ and analyze the possibility of occurrence of a spin-polarized KT superfluid.
Energy Technology Data Exchange (ETDEWEB)
Holmlid, Leif, E-mail: holmlid@chem.gu.se [Atmospheric Science, Department of Chemistry, University of Gothenburg, SE-412 96 Göteborg (Sweden); Kotzias, Bernhard [Airbus DS, Department Mechanical Engineering, D28199 Bremen (Germany)
2016-04-15
Ultra-dense hydrogen H(0) with its typical H-H bond distance of 2.3 pm is superfluid at room temperature as expected for quantum fluids. It also shows a Meissner effect at room temperature, which indicates that a transition point to a non-superfluid state should exist above room temperature. This transition point is given by a disappearance of the superfluid long-chain clusters H{sub 2N}(0). This transition point is now measured for several metal carrier surfaces at 405 - 725 K, using both ultra-dense protium p(0) and deuterium D(0). Clusters of ordinary Rydberg matter H(l) as well as small symmetric clusters H{sub 4}(0) and H{sub 3}(0) (which do not give a superfluid or superconductive phase) all still exist on the surface at high temperature. This shows directly that desorption or diffusion processes do not remove the long superfluid H{sub 2N}(0) clusters. The two ultra-dense forms p(0) and D(0) have different transition temperatures under otherwise identical conditions. The transition point for p(0) is higher in temperature, which is unexpected.
Excitations of Superfluid ^4He at Wavevectors Beyond the Roton
Glyde, Henry; Sakhel, Asaad
2002-03-01
We present a Quantum Field Theoretical Model that reproduces the basic features of the temperature dependence of the dynamic structure factor S(Q,ω) of ^4He as observed in the inelastic-neutron scattering data taken at ISIS( J. V. Pierce, R. T. Azuah, B. F, A. R. Sakhel, H. R. Glyde, W. G. Stirling, J. Phys: Cond. Matter, 13(2001) 4421., UK. A range of the wavevectors Q beyond the roton (Q > 2.0 Åis considered. The model is able to reproduce the decrease in the intensity of the single-particle excitation peak with increase of T in the range 0.6 accounted for by a momentum (k) and temperature dependent width of the Landau-Khalatnikov form (H. R. Glyde, Excitations in Liquid and Solid helium), Oxford, Clarendron Press, (1994)..
Theoretical study of third sound in a layered superfluid film
International Nuclear Information System (INIS)
Cheng, E.; Saam, W.F.; Cole, M.W.; Treiner, J.
1993-01-01
The authors present a calculation of the third sound speed c 3 of thin 4 He films adsorbed on H 2 , Li, Mg, graphite and H 2 -plated graphite. The results show a clear correlation of oscillations in c 3 , with a period of one atomic layer, with the layering phenomena observed in adsorption isotherms. Comparison is made with recent experimental results for helium films on solid H 2 by Shirron and Mochel and by Brisson, Mester and Silvera. The theoretical analysis suggests explanations for disagreements between different interpretations of data. A standard way of determining the number of so-called inert layers is questioned. Other available experimental data on graphite and H 2 -plated graphite are also discussed
Directory of Open Access Journals (Sweden)
Philipp Strack
2014-04-01
Full Text Available We study the nature of superfluid pairing in imbalanced Fermi mixtures in two spatial dimensions. We present evidence that the combined effect of Fermi surface mismatch and order parameter fluctuations of the superfluid condensate can lead to continuous quantum phase transitions from a normal Fermi mixture to an intermediate Sarma-Liu-Wilczek superfluid with two gapless Fermi surfaces—even when mean-field theory (incorrectly predicts a first-order transition to a phase-separated “Bardeen-Cooper-Schrieffer plus excess fermions” ground state. We propose a mechanism for non-Fermi-liquid behavior from repeated scattering processes between the two Fermi surfaces and fluctuating Cooper pairs. Prospects for experimental observation with ultracold atoms are discussed.
Superfluidity in two-dimensions. A thermal conductivity study of 4He and 3He- 4He mixture films
International Nuclear Information System (INIS)
Finotello, D.
1992-01-01
We review measurement of the thermal transport of 4 He films and 3 He- 4 He mixture films near the superfluid transition. These measurements were performed on helium films of thickness ranging from 12 to 156 A and mixture films with 3 He concentration up to 2%. The superfluid transition temperature for these films ranged from 1.2 to 2.2. K. We discuss universal features of the data as well as the behavior of the ratio of the vortex diffusion constant to vortex core-parameter, the sharpness of the transition and the superfluid transition temperature as a function of thickness and concentration. We also describe new experiments that will contribute to a better understanding of the observed behavior (Author)
Tunneling dynamics of superfluid Fermi gases in an accelerating optical lattice
International Nuclear Information System (INIS)
Tie Lu; Xue Jukui
2010-01-01
The nonlinear Landau-Zener tunneling and the nonlinear Rabi oscillations of superfluid Fermi gases between Bloch bands in an accelerating optical lattice are discussed. Within the hydrodynamic theory and a two-level model, the tunneling probability of superfluid Fermi gases between Bloch bands is obtained. We find that, as the system crosses from the Bose-Einstein condensation (BEC) side to the BCS side, the tunneling rate is closely related to the particle density: when the density is smaller (larger) than a critical value, the tunneling rate at unitarity is larger (smaller) than that in the BEC limit. This is well explained in terms of an effective interaction and an effective potential. Furthermore, the nonlinear Rabi oscillations of superfluid Fermi gases between the bands are discussed by imposing a periodic modulation on the level bias and the strength of the lattice. Analytical expressions of the critical density for suppressing or enhancing the Rabi oscillations are obtained. It is shown that, as the system crosses from the BEC side to the BCS side, the critical density strongly depends on the modulation parameters (i.e., the modulation amplitude and the modulation frequency). For a fixed density, a high-frequency or low-frequency modulation can suppress or enhance the Rabi oscillations both at unitarity and in the BEC limit. For an intermediate modulation frequency, the Rabi oscillations are chaotic along the entire BEC-BCS crossover, especially, on the BCS side. Interestingly, we find that the modulation of the lattice strength only with an intermediate modulation frequency has significant effect on the Rabi oscillations both in the BEC limit and at unitarity; that is, an intermediate-frequency modulation can enhance the Rabi oscillations, especially on the BCS side.
A PISO-like algorithm to simulate superfluid helium flow with the two-fluid model
Soulaine, Cyprien; Allain, Hervé; Baudouy, Bertrand; Van Weelderen, Rob
2015-01-01
This paper presents a segregated algorithm to solve numerically the superfluid helium (He II) equations using the two-fluid model. In order to validate the resulting code and illustrate its potential, different simulations have been performed. First, the flow through a capillary filled with He II with a heated area on one side is simulated and results are compared to analytical solutions in both Landau and Gorter–Mellink flow regimes. Then, transient heat transfer of a forced flow of He II is investigated. Finally, some two-dimensional simulations in a porous medium model are carried out.
Liepmann, H. W.; Torczynski, J. R.
1983-01-01
Second sound techniques were used to study superfluid helium. Second sound shock waves produced relative velocities in the bulk fluid. Maximum counterflow velocities produced in this way are found to follow the Langer-Fischer prediction for the fundamental critical velocity in its functional dependence on temperature and pressure. Comparison of successive shock and rotating experiments provides strong evidence that breakdown results in vorticity production in the flow behind the shock. Schlieren pictures have verified the planar nature of second sound shocks even after multiple reflections. The nonlinear theory of second sound was repeatedly verified in its prediction of double shocks and other nonlinear phenomena.
Vortex line in a neutral finite-temperature superfluid Fermi gas
DEFF Research Database (Denmark)
Nygaard, Nicolai; Bruun, G. M.; Schneider, B. I.
2004-01-01
The structure of an isolated vortex in a dilute two-component neutral superfluid Fermi gas is studied within the context of self-consistent Bogoliubov-de Gennes theory. Various thermodynamic properties are calculated, and the shift in the critical temperature due to the presence of the vortex is ...... is analyzed. The gapless excitations inside the vortex core are studied, and a scheme to detect these states and thus the presence of the vortex is examined. The numerical results are compared with various analytical expressions when appropriate....
Mohan, Priyanka; Goldbart, Paul M; Narayanan, Rajesh; Toner, John; Vojta, Thomas
2010-08-20
We show that layered quenched randomness in planar magnets leads to an unusual intermediate phase between the conventional ferromagnetic low-temperature and paramagnetic high-temperature phases. In this intermediate phase, which is part of the Griffiths region, the spin-wave stiffness perpendicular to the random layers displays anomalous scaling behavior, with a continuously variable anomalous exponent, while the magnetization and the stiffness parallel to the layers both remain finite. Analogous results hold for superfluids and superconductors. We study the two phase transitions into the anomalous elastic phase, and we discuss the universality of these results, and implications of finite sample size as well as possible experiments.
Knotted Solitons in an Interacting Mixture of a Charged and a Neutral Superfluid for Neutron Stars
International Nuclear Information System (INIS)
Ren Jirong; Guo Heng; Zhang Xinhui; Li Ran
2009-01-01
By making use of the decomposition of U(1) gauge potential theory and the φ-mapping method we discuss a mixture of interacting neutral and charged Bose condensates, which is supposed being realized in the interior of neutron stars in the form of a coexistent neutron superfluid and protonic superconductor. We propose that this system possesses vortex lines and two classes of knotted solitons. The topological charge of the vortex lines are characterized by the Hopf indices and the Brower degrees of φ-mapping, and the knotted solitons are described by nontrivial Hopf invariant and the BF action respectively.
Topological Aspects in an Interacting Mixture of a Charged and a Neutral Superfluid in Neutron Stars
International Nuclear Information System (INIS)
Ji-Rong, Ren; Heng, Guo; Xin-Hui, Zhang; Ran, Li
2009-01-01
By making use of the decomposition of U(1) gauge potential theory and the ø-mapping method we discuss a mixture of interacting neutral and charged Bose condensates, which is supposed to be realized in the interior of neutron stars in the form of a coexistent neutron superfluid and protonic superconductor. We propose that this system possesses vortex line knotted solitons and the topological charges of vortex lines are characterized by the winding numbers of the ø-mapping. Furthermore the spatial bifurcation of vortices is also discussed. (geophysics, astronomy, and astrophysics)
Laser spectroscopy of exotic RI atoms in superfluid helium-OROCHI experiment
International Nuclear Information System (INIS)
Furukawa, T.; Matsuo, Y.; Hatakeyama, A.; Fujikake, K.; Matsuura, Y.; Kobayashi, T.; Shimoda, T.
2010-01-01
We have been developing a new laser spectroscopic technique 'OROCHI,' which is based on the combination of superfluid helium as a stopper of radioactive isotope (RI) beam and in-situ laser spectroscopy of RI atoms, for determining spins and moments of exotic RIs. By using this unique technique, it is feasible to measure nuclear spins and electromagnetic moments of extremely low yield RI (estimated as less than 1 pps). Recently, we have demonstrated that nuclear spins and moments are obtained from Zeeman and hyperfine splittings of stable Rb isotopes measured using this OROCHI technique. Details of this laser spectroscopy method in He II 'OROCHI' and the summary of our development are presented.
McKenzie, Ross Hugh
A brief overview of past experimental and theoretical investigations of the linear and nonlinear interaction of zero sound with the order parameter collective modes in superfluid ^3He-B is given before introducing the quasiclassical (QC) theory of superfluid ^3He. A new approach to calculating the linear and nonlinear response is presented. The QC propagator is calculated by expanding the low energy Dyson's equation in powers of the nonequilibrium self energy. The expression given for the expansion coefficients, involving products of pairs of equilibrium Green's functions, has a simple diagrammatic representation, and establishes a connection between the QC theory and other theoretical formalisms which have been used to investigate the collective modes. It is shown that the expansion coefficients satisfy Onsager-like relations and some identities required by gauge and galilean invariance. Consequently, this new approach to deriving dynamical equations for the collective modes is more efficient and transparent than solving the QC transport equations. This new approach is used to investigate the linear coupling of zero sound to the order parameter collective modes in weakly inhomogeneous superfluid ^3 He. It makes tractable the treatment of (nonlinear) parametric processes involving zero sound and the collective modes. It is shown that the approximate particle-hole symmetry of the ^3He Fermi liquid determines important selection rules for nonlinear acoustic processes, just as it is well known to do for linear processes. Analogues with nonlinear optics guide the derivation, solution and interpretation of the dynamical equations for a three-wave resonance between two zero sound waves and the J = 2 ^+ order parameter collective mode. It is shown that stimulated Raman scattering and two phonon absorption of zero sound by the J = 2^+ collective mode should be observable when the pump sound wave has energy density larger than about one percent of the superfluid
Generic strong coupling behavior of Cooper pairs in the surface of superfluid nuclei
Energy Technology Data Exchange (ETDEWEB)
Pillet, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France); Sandulescu, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France)]|[Institute of Physics and Nuclear Engineering, 76900 Bucharest (Romania)]|[Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France)]|[Universite Paris-Sud, Orsay, F-91505 (France)
2007-01-15
With realistic HFB calculations, using the D1S Gogny force, we reveal a generic behavior of concentration of small sized Cooper pairs (2-3 fm) in the surface of superfluid nuclei. This study confirms and extends previous results given in the literature that use more schematic approaches. It is shown that the strong concentration of pair probability of small Cooper pairs in the nuclear surface is a quite general and generic feature and that nuclear pairing is much closer to the strong coupling regime than previously assumed.
From cosmology to cold atoms: observation of Sakharov oscillations in a quenched atomic superfluid.
Hung, Chen-Lung; Gurarie, Victor; Chin, Cheng
2013-09-13
Predicting the dynamics of many-body systems far from equilibrium is a challenging theoretical problem. A long-predicted phenomenon in hydrodynamic nonequilibrium systems is the occurrence of Sakharov oscillations, which manifest in the anisotropy of the cosmic microwave background and the large-scale correlations of galaxies. Here, we report the observation of Sakharov oscillations in the density fluctuations of a quenched atomic superfluid through a systematic study in both space and time domains and with tunable interaction strengths. Our work suggests a different approach to the study of nonequilibrium dynamics of quantum many-body systems and the exploration of their analogs in cosmology and astrophysics.
Dual Superfluid-Bose-Glass Critical Point in Two Dimensions and the Universal Conductivity
International Nuclear Information System (INIS)
Herbut, I.F.
1997-01-01
The continuum version of the dual theory for a system of two-dimensional quantum disordered bosons with statistical particle-hole symmetry and at T=0 admits a new disordered critical point within the renormalization group calculation at fixed dimension. We obtain the universal conductivity and the critical exponents at the superfluid-Bose glass transition in the system: σ c =0.25(2e) 2 /h , ν=1.38 , and z=1.93 , to the lowest order in fixed-point values of the dual coupling constants. copyright 1997 The American Physical Society
Zadorozhko, A A; Rudavskij, E Y; Chagovets, V K; Sheshin, G A
2003-01-01
The temperature and concentration gradients nabla T and nabla x in a superfluid sup 3 He- sup 4 He mixture with an initial concentration 9,8 % of sup 3 He are measured in a temperature range 70-500 mK. The gradients are produced by a steady thermal flow with heating from below. It is shown that the value of nabla x/nabla T observed in the experiment is in good agreement with the theoretical model derived from the temperature and concentration dependences of osmotic pressure. The experimental data permitted us to obtain a thermal diffusion ratio of the solution responsible for the thermal diffusion coefficient.
Salort, J; Monfardini, A; Roche, P-E
2012-12-01
We present a new type of cryogenic local velocity probe that operates in liquid helium (1 K < T < 4.2 K) and achieves a spatial resolution of ≈ 0.1 mm. The operating principle is based on the deflection of a micro-machined silicon cantilever which reflects the local fluid velocity. Deflection is probed using a superconducting niobium micro-resonator sputtered on the sensor and used as a strain gauge. We present the working principle and the design of the probe, as well as calibration measurements and velocity spectra obtained in a turbulent helium flow above and below the superfluid transition.
Hagen Kleinert
2018-01-01
This is an introductory book dealing with collective phenomena in many-body systems. A gas of bosons or fermions can show oscillations of various types of density. These are described by different combinations of field variables. Especially delicate is the competition of these variables. In superfluid 3He, for example, the atoms can be attracted to each other by molecular forces, whereas they are repelled from each other at short distance due to a hardcore repulsion. The attraction gives rise to Cooper pairs, and the repulsion is overcome by paramagnon oscillations. The combination is what finally led to the discovery of superfluidity in 3He. In general, the competition between various channels can most efficiently be studied by means of a classical version of the Hubbard-Stratonovich transformation. A gas of electrons is controlled by the interplay of plasma oscillations and pair formation. In a system of rod- or disc-like molecules, liquid crystals are observed with directional orientations that behave in ...
Koettig, T; Avellino, S; Junginger, T; Bremer, J
2015-01-01
Oscillating Superleak Transducers (OSTs) can be used to localize quenches of superconducting radio-frequency cavities. Local hot spots at the cavity surface initiate temperature waves in the surrounding superfluid helium that acts as cooling fluid at typical temperatures in the range of 1.6 K to 2 K. The temperature wave is characterised by the properties of superfluid helium such as the second sound velocity. For high heat load densities second sound velocities greater than the standard literature values are observed. This fast propagation has been verified in dedicated small scale experiments. Resistors were used to simulate the quench spots under controlled conditions. The three dimensional propagation of second sound is linked to OST signals. The aim of this study is to improve the understanding of the OST signal especially the incident angle dependency. The characterised OSTs are used as a tool for quench localisation on a real size cavity. Their sensitivity as well as the time resolution was proven to b...
Microscopic study of {sup 1}S{sub 0} superfluidity in dilute neutron matter
Energy Technology Data Exchange (ETDEWEB)
Pavlou, G.E.; Mavrommatis, E. [National and Kapodistrian University of Athens, Physics Department, Division of Nuclear and Particle Physics, Athens (Greece); Moustakidis, C. [Aristotelian University of Thessaloniki, Department of Theoretical Physics, Thessaloniki (Greece); Clark, J.W. [Washington University, McDonnell Center for the Space Sciences and Department of Physics, St. Louis, MO (United States); University of Madeira, Center for Mathematical Sciences, Funchal (Portugal)
2017-05-15
Singlet S-wave superfluidity of dilute neutron matter is studied within the correlated BCS method, which takes into account both pairing and short-range correlations. First, the equation of state (EOS) of normal neutron matter is calculated within the Correlated Basis Function (CBF) method in the lowest cluster order using the {sup 1}S{sub 0} and {sup 3}P components of the Argonne V{sub 18} potential, assuming trial Jastrow-type correlation functions. The {sup 1}S{sub 0} superfluid gap is then calculated with the corresponding component of the Argonne V{sub 18} potential and the optimally determined correlation functions. The dependence of our results on the chosen forms for the correlation functions is studied, and the role of the P-wave channel is investigated. Where comparison is meaningful, the values obtained for the {sup 1}S{sub 0} gap within this simplified scheme are consistent with the results of similar and more elaborate microscopic methods. (orig.)
Kosterlitz-Thouless superfluid transition for thin helium-4 films adsorbed in porous media
International Nuclear Information System (INIS)
Kotsubo, V.Y.
1985-01-01
Thin helium-4 films adsorbed in porous media with small grain sizes are studied in an attempt to understand size effects on the thin-film superfluid transition. Films were adsorbed in 500A, 3000A, and 1μ diameter packed alumina powders, and the superfluidity density was probed using third sound. The main features observed are a broadening of the transition and a reduction of third sound attenuation as the grain sizes are reduced. To explain the results, the flat-substrate Kosterlitz-Thouless theory is adapted to a finite-size system. The model, which is based on the behavior of thermally excited vortices, qualitatively agrees with the experimental results. Fits to the sound velocity data produces reasonable values for the parameters of the vortices, but quantitative agreement with the attenuation data could not be achieved. The overall results of this study suggests that the transition evolves continuously as the geometry changes form the flat substrate down to this small scale systems
Interaction of ions, atoms, and small molecules with quantized vortex lines in superfluid (4)He.
Mateo, David; Eloranta, Jussi; Williams, Gary A
2015-02-14
The interaction of a number of impurities (H2, Ag, Cu, Ag2, Cu2, Li, He3 (+), He(*) ((3)S), He2 (∗) ((3)Σu), and e(-)) with quantized rectilinear vortex lines in superfluid (4)He is calculated by using the Orsay-Trento density functional theory (DFT) method at 0 K. The Donnelly-Parks (DP) potential function binding ions to the vortex is combined with DFT data, yielding the impurity radius as well as the vortex line core parameter. The vortex core parameter at 0 K (0.74 Å) obtained either directly from the vortex line geometry or through the DP potential fitting is smaller than previously suggested but is compatible with the value obtained from re-analysis of the Rayfield-Reif experiment. All of the impurities have significantly higher binding energies to vortex lines below 1 K than the available thermal energy, where the thermally assisted escape process becomes exponentially negligible. Even at higher temperatures 1.5-2.0 K, the trapping times for larger metal clusters are sufficiently long that the previously observed metal nanowire assembly in superfluid helium can take place at vortex lines. The binding energy of the electron bubble is predicted to decrease as a function of both temperature and pressure, which allows adjusting the trap depth for either permanent trapping or to allow thermally assisted escape. Finally, a new scheme for determining the trapping of impurities on vortex lines by optical absorption spectroscopy is outlined and demonstrated for He(*).
AUTHOR|(SzGeCERN)673023; Blanco Viñuela, Enrique
In each of eight arcs of the 27 km circumference Large Hadron Collider (LHC), 2.5 km long strings of super-conducting magnets are cooled with superfluid Helium II at 1.9 K. The temperature stabilisation is a challenging control problem due to complex non-linear dynamics of the magnets temperature and presence of multiple operational constraints. Strong nonlinearities and variable dead-times of the dynamics originate at strongly heat-flux dependent effective heat conductivity of superfluid that varies three orders of magnitude over the range of possible operational conditions. In order to improve the temperature stabilisation, a proof of concept on-line economic output-feedback Non-linear Model Predictive Controller (NMPC) is presented in this thesis. The controller is based on a novel complex first-principles distributed parameters numerical model of the temperature dynamics over a 214 m long sub-sector of the LHC that is characterized by very low computational cost of simulation needed in real-time optimizat...
Development of a proof of concept low temperature 4He Superfluid Magnetic Pump
Jahromi, Amir E.; Miller, Franklin K.
2017-03-01
We describe the development and experimental results of a proof of concept Superfluid Magnetic Pump in this work. This novel low temperature, no moving part pump can replace the existing bellows-piston driven 4He or 3He-4He mixture compressor/circulators used in various sub Kelvin refrigeration systems such as dilution, Superfluid pulse tube, Stirling, or active magnetic regenerative refrigerators. Due to the superior thermal transport properties of sub-Lambda 4He this pump can also be used as a simple circulator to distribute cooling over large surface areas. Our pump was experimentally shown to produce a maximum flow rate of 440 mg/s (averaged over cycle), 665 mg/s (peak) and produced a maximum pressure difference of 2323 Pa using only the more common isotope of helium, 4He. This pump worked in an ;ideal; thermodynamic state: The experimental results matched with the theoretical values predicted by a computer model. Pump curves were developed to map the performance of this pump. This successful demonstration will enable this novel pump to be implemented in suitable sub Kelvin refrigeration systems.
Light Higgs channel of the resonant decay of magnon condensate in superfluid (3)He-B.
Zavjalov, V V; Autti, S; Eltsov, V B; Heikkinen, P J; Volovik, G E
2016-01-08
In superfluids the order parameter, which describes spontaneous symmetry breaking, is an analogue of the Higgs field in the Standard Model of particle physics. Oscillations of the field amplitude are massive Higgs bosons, while oscillations of the orientation are massless Nambu-Goldstone bosons. The 125 GeV Higgs boson, discovered at Large Hadron Collider, is light compared with electroweak energy scale. Here, we show that such light Higgs exists in superfluid (3)He-B, where one of three Nambu-Goldstone spin-wave modes acquires small mass due to the spin-orbit interaction. Other modes become optical and acoustic magnons. We observe parametric decay of Bose-Einstein condensate of optical magnons to light Higgs modes and decay of optical to acoustic magnons. Formation of a light Higgs from a Nambu-Goldstone mode observed in (3)He-B opens a possibility that such scenario can be realized in other systems, where violation of some hidden symmetry is possible, including the Standard Model.
International Nuclear Information System (INIS)
Pentlehner, D.; Slenczka, A.
2015-01-01
Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time
Villois, Alberto; Salman, Hayder
2018-03-01
We study the motion of an electron bubble in the zero-temperature limit where neither phonons nor rotons provide a significant contribution to the drag exerted on an ion moving within the superfluid. By using the Gross-Clark model, in which a Gross-Pitaevskii equation for the superfluid wave function is coupled to a Schrödinger equation for the electron wave function, we study how vortex nucleation affects the measured drift velocity of the ion. We use parameters that give realistic values of the ratio of the radius of the bubble with respect to the healing length in superfluid 4He at a pressure of one bar. By performing fully three-dimensional spatiotemporal simulations of the superfluid coupled to an electron, that is modeled within an adiabatic approximation and moving under the influence of an applied electric field, we are able to recover the key dynamics of the ion-vortex interactions that arise and the subsequent ion-vortex complexes that can form. Using the numerically computed drift velocity of the ion as a function of the applied electric field, we determine the vortex nucleation limited mobility of the ion to recover values in good agreement with measured data.
Czech Academy of Sciences Publication Activity Database
Yulin, A.V.; Bludov, Yu.V.; Konotop, V. V.; Kuzmiak, Vladimír; Salerno, M.
2013-01-01
Roč. 87, č. 3 (2013) ISSN 1050-2947 R&D Projects: GA MŠk LH12009 Institutional support: RVO:67985882 Keywords : Superfluidity * Bose-Einstein condensates * Matter Waves Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.991, year: 2013
Schwartz, Sylvain; Gutty, François; Feugnet, Gilles; Bouyer, Philippe; Pocholle, Jean-Paul
2008-05-09
We report fine-tuning of nonlinear interactions in a solid-state ring laser gyroscope by vibrating the gain medium along the cavity axis. We demonstrate both experimentally and theoretically that nonlinear interactions vanish for some values of the vibration parameters, leading to quasi-ideal rotation sensing. We eventually point out that our conclusions can be mapped onto other subfields of physics such as ring-shaped superfluid configurations, where nonlinear interactions could be tuned by using Feshbach resonance.
Topological Fulde-Ferrell superfluid in spin-orbit-coupled atomic Fermi gases
Liu, Xia-Ji; Hu, Hui
2013-08-01
We theoretically predict a topological matter—topological inhomogeneous Fulde-Ferrell superfluid—in one-dimensional atomic Fermi gases with equal Rashba and Dresselhaus spin-orbit coupling near s-wave Feshbach resonances. The realization of such a spin-orbit-coupled Fermi system has already been demonstrated recently by using a two-photon Raman process and the extra one-dimensional confinement is easy to achieve using a tight two-dimensional optical lattice. The topological Fulde-Ferrell superfluid phase is characterized by a nonzero center-of-mass momentum and a nontrivial Berry phase. By tuning the Rabi frequency and the detuning of Raman laser beams, we show that such an exotic topological phase occupies a significant part of parameter space and therefore it could be easily observed experimentally, by using, for example, momentum-resolved and spatially resolved radio-frequency spectroscopy.
Cable Insulation Scheme to Improve Heat Transfer to Superfluid Helium in Nb-Ti Accelerator Magnets
La China, M
2008-01-01
In superconducting magnets operating at high heat loads as the ones for interaction region of particle colliders or for fast cycling synchrotrons, the limited heat transfer capability of state-of-the-art electrical insulation may constitute a heavy limitation to performance. In the LHC main magnets, Nb-Ti epoxy-free insulation, composed of polyimide tapes, has proved to be permeable to superfluid helium, however the heat flux is rather limited. After a review of the standard insulation scheme for Nb-Ti and of the associated heat transfer mechanisms, we show the existence of a large margin available to improve insulation permeability.We propose a possible way to profit of such a margin in order to increase significantly the maximum heat flux drainable from an all polyimide insulated Nb-Ti coil, as it is used in modern accelerator magnets.
Random textures of the order parameter of superfluid sup 3 He-B in aerogel
Fomin, Yu A
2002-01-01
The scheme for describing the properties of the superfluid sup 3 He in the aerogel is proposed in accordance with the Ginzburg and Landau theory. The aerogel effect on the order parameter is described by the random tensor field. This field exerts desorientation effect on the order parameter in the sup 3 He A-phase, but it does not influence the order parameter orientation in the B-phase, if there is no magnetic field. The change in the order parameter texture, originating in the B-phase in the aerogel in the magnetic field, is considered. Fluctuations of the sup 3 He-B anisotropy axis direction are correlated on the length, inversely proportional to the field intensity and having the macroscopic scale
Study of Transient Heat Transport Mechanisms in Superfluid Helium Cooled Rutherford-Cables
AUTHOR|(CDS)2100615
The Large Hadron Collider leverages superconducting magnets to focus the particle beam or keep it in its circular track. These superconducting magnets are composed of NbTi-cables with a special insulation that allows superfluid helium to enter and cool the superconducting cable. Loss mechanisms, e.g. continuous random loss of particles escaping the collimation system heating up the magnets. Hence, a local temperature increase can occur and lead to a quench of the magnets when the superconductor warms up above the critical temperature. A detailed knowledge about the temperature increases in the superconducting cable (Rutherford type) ensures a secure operation of the LHC. A sample of the Rutherford cable has been instrumented with temperature sensors. Experiments with this sample have been performed within this study to investigate the cooling performance of the helium in the cable due to heat deposition. The experiment uses a superconducting coil, placed in a cryostat, to couple with the magnetic field loss m...
Directory of Open Access Journals (Sweden)
Sekizawa Kazuyuki
2017-01-01
Full Text Available Recently, we have reported a novel role of pairing in low-energy heavy ion reactions at energies above the Coulomb barrier, which may have a detectable impact on reaction outcomes, such as the kinetic energy of fragments and the fusion cross section [arXiv:1611.10261, arXiv:1702.00069]. The phenomenon mimics the one studied experimentally with ultracold atomic gases, where two clouds of fermionic superfluids with different phases of the pairing fields are forced to merge, inducing various excitation modes of the pairing field. Although it originates from the phase difference of the pairing fields, the physics behind it is markedly different from the so-called Josephson effect. In this short contribution, we will briefly outline the results discussed in our recent papers and explain relations with the field of ultracold atomic gases.
Third sound measurements of superfluid 4He films on multiwall carbon nanotubes below 1 K
International Nuclear Information System (INIS)
Menachekanian, Emin; Abraham, John B S; Chen, Bob; Iaia, Vito; Li, Andrew; Williams, Gary A
2014-01-01
Third sound is studied for superfluid films of 4He adsorbed on multiwall carbon nanotubes packed into an annular resonator. The third sound is generated with mechanical oscillation of the cell, and detected with carbon bolometers. A filling curve at temperatures near 250 mK shows oscillations in the third sound velocity, with maxima at the completion of the 4th and 5th atomic layers. Sharp changes in the Q factor of the third sound are found at partial layer fillings. Temperature sweeps at a number of fill points show strong broadening effects on the Kosterlitz-Thouless (KT) transition, and rapidly increasing dissipation, in qualitative agreement with the predictions of Machta and Guyer. At the 4th layer completion there is a sudden reduction of the transition temperature T KT , and then a recovery back to linear variation with temperature, although the slope is considerably smaller than the KT prediction
Design and Fabrication of Superfluid Heat Exchanger Tubes for the LHC Superconducting Magnets
Bertinelli, F; Favre, G; Ferreira, L M A; Rossi, L; Savary, F
2004-01-01
The dipole and quadrupole cold masses of the LHC machine require about 1 700 heat exchanger tubes (HET). In operation the HET carries a two-phase flow of superfluid helium at sub-atmospheric pressure. The HET consists of an oxygen-free, seamless copper tube equipped with stainless steel ends. After an evaluation of different alternatives, a design based on the technologies of vacuum brazing and electron beam welding has been adopted. Presence of these multiple technologies at CERN and synergies with the cleaning, handling and transport of other 15-metre components for LHC, motivated CERN to undertake this series fabrication on site. The raw copper tubes are procured in industry, presenting challenging issues of geometric precision. Organisation of the HET fabrication includes cryomeasurements to validate cleaning procedures, characterisation of welding procedures, design and experimental verification of buckling pressure, quality control during series production. The series fabrication of these long, multi-te...
PIP-II Cryogenic System and the evolution of Superfluid Helium Cryogenic Plant Specifications
Energy Technology Data Exchange (ETDEWEB)
Chakravarty, Anindya [Fermilab; Rane, Tejas [Fermilab; Klebaner, Arkadiy [Fermilab
2017-07-06
The PIP-II cryogenic system consists of a Superfluid Helium Cryogenic Plant (SHCP) and a Cryogenic Distribution System (CDS) connecting the SHCP to the Superconducting (SC) Linac consisting of 25 cryomodules. The dynamic heat load of the SC cavities for continuous wave (CW) as well as pulsed mode of operation has been listed out. The static heat loads of the cavities along with the CDS have also been discussed. Simulation study has been carried out to compute the supercritical helium (SHe) flow requirements for each cryomodule. Comparison between the flow requirements of the cryomodules for the CW and pulsed modes of operation have also been made. From the total computed heat load and pressure drop values in the CDS, the basic specifications for the SHCP, required for cooling the SC Linac, have evolved.
Effective mass of 4He atom in superfluid and normal phases
International Nuclear Information System (INIS)
Vakarchuk, Yi.O.; Grigorchak, O.Yi.; Pastukhov, V.S.; Pritula, R.O.
2016-01-01
The formula for the temperature dependence of the effective mass of a 4 He atom in the superfluid and normal phases is obtained. This expression for the effective mass allows one to eliminate infra-red divergences, being applicable at all temperatures, except for a narrow fluctuation region 0.97< < approx T/T c <=1. In the high and low temperature limits, as well as in the interactionless limit, the obtained expression reproduces the well known results. The temperature dependence of the heat capacity and the phase transition temperature T c ∼2.18 K are calculated, by using the formula obtained for the effective mass. In the framework of the approach proposed in this work, the small critical index η is determined in the random phase approximation. The obtained value corresponds to the well known result
Kelvin-wave cascade and dissipation in low-temperature superfluid vortices.
Krstulovic, Giorgio
2012-11-01
We study the statistical properties of the Kelvin waves propagating along quantized superfluid vortices driven by the Gross-Pitaevskii equation. No artificial forcing or dissipation is added. Vortex positions are accurately tracked. This procedure directly allows us to obtain the Kevin-wave occupation-number spectrum. Numerical data obtained from long time integration and ensemble average over initial conditions support the spectrum proposed in L'vov and Nazarenko [JETP Lett. 91, 428 (2010)]. Kelvin-wave modes in the inertial range are found to be Gaussian as expected by weak-turbulence predictions. Finally the dissipative range of the Kelvin-wave spectrum is studied. Strong non-Gaussian fluctuations are observed in this range.
Final-state effects on superfluid 4He in the deep inelastic regime
International Nuclear Information System (INIS)
Mazzanti, F.; Boronat, J.; Polls, A.
1996-01-01
A study of final-state effects (FSE) on the dynamic structure function of superfluid 4 He in the Gersch-Rodriguez formalism is presented. The main ingredients needed in the calculation are the momentum distribution and the semidiagonal two-body density matrix. The influence of these ground-state quantities on the FSE is analyzed. A variational form of ρ 2 is used, even though simpler forms turn out to give accurate results if properly chosen. Comparison to the experimental response at high momentum transfer is performed. The predicted response is quite sensitive to slight variations on the value of the condensate fraction, the best agreement with experiment being obtained with n 0 =0.082. Sum rules of the FSE broadening function are also derived and commented. Finally, it is shown that Gersch-Rodriguez theory produces results as accurate as those coming from other more recent FSE theories. copyright 1996 The American Physical Society
Superfluid density and superconducting transition temperature in dirty iron-based superconductors
Energy Technology Data Exchange (ETDEWEB)
Hartmann, Thomas; Ahn, Felix; Eremin, Ilya [Ruhr-Universitaet Bochum, Bochum (Germany)
2016-07-01
Measurements on optimally electron doped LaFeAsO{sub 1-x}F{sub x} samples under pressure up to ∝23 kbar reveal a clear mutual independence between the critical temperature T{sub c} and the ratio of superfluid density over effective band mass of Cooper pairs n{sub s}/m*. The ratio increases about ∝30 % at the maximum pressure whereas T{sub c} remains constant, which clearly implies a breakdown of the Uemura relation in LaFeAsO{sub 1-x}F{sub x}. Here we analyze theoretically this effect by taking into account the effect of nonmagnetic impurities in a multi-band superconductor. We show that the ratio between intra-band and inter-band scattering rates can explain the behaviour of the observables under pressure by only acting on structural parameters while the amount of chemical disorder is still constant.
Mutual friction in superfluid He3-B in the low-temperature regime
Mäkinen, J. T.; Eltsov, V. B.
2018-01-01
We measure the response of a rotating sample of superfluid He3-B to spin-down to rest in the zero-temperature limit. Deviations from perfect cylindrical symmetry in the flow environment cause the initial response to become turbulent. The remaining high polarization of vortices along the rotation axis suppresses the turbulent behavior and leads to laminar late-time response. We determine the dissipation during laminar decay at (0.13 -0.22 ) Tc from the precession frequency of the remnant vortex cluster. We extract the mutual friction parameter α and confirm that its dependence on temperature and pressure agrees with theoretical predictions. We find that the zero-temperature extrapolation of α has pressure-independent value α (T =0 ) ˜5 ×10-4 , which we attribute to a process where Kelvin waves, excited at surfaces of the container, propagate into the bulk and enhance energy dissipation via overheating vortex core-bound fermions.
Possible crossover to percolation scenario near superfluid-Bose-glass transition
Syromyatnikov, A. V.; Sizanov, A. V.
2017-10-01
We discuss magnetically ordered (;superfluid;) phase near quantum transition to Bose-glass phase in a simple modeling system, Heisenberg antiferromagnet in spatial dimension d > 2 in external magnetic field with disorder in exchange coupling constants. Our analytical consideration is based on hydrodynamic description of long-wavelength excitations and it is valid in the entire critical region near the quantum critical point (QCP). We demonstrate that the system behaves in full agreement with predictions by Fisher et al. (Phys. Rev. B 40, 546 (1989)) in close vicinity of QCP. On the other hand, we show that many recent experimental and numerical results obtained in various 3D systems can be described by our formulas using percolation critical exponents. Then, it is a possibility that a percolation critical regime arises in the ordered phase in some 3D systems not very close to QCP.
Photo-induced isomerization and chemical reaction dynamics in superfluid helium droplets
Merritt, Jeremy; Douberly, Gary; Miller, Roger
2008-03-01
Near threshold photo-induced isomerization and photo-induced chemical reactions have long been sough after as sensitive probes of the underlying potential energy surface. One of the most important questions asked is how the initially bright quantum state couples to the reaction coordinate, and thus relates to energy transfer in general. Helium droplets have now allowed us to stabilize entrance channel clusters behind very small reaction barriers such that vibrational excitation may result in reaction. Through two examples, namely the isomerization of the 2 binary complexes of HF-HCN Douberly et al. PCCP 2005, 7,463, and the induced reaction of the gallium-HCN complex Merritt et al. JPCA 2007, DOI:10.1021/jp074981e we will show how the branching ratios for reaction and predissociation can determined and the influence of the superfluid He solvent.
Rigol, Marcos; Olshanii, Maxim; Muramatsu, Alejandro
2007-03-01
We study the nonequilibrium dynamics of hard-core bosons (HCB's) on one-dimensional lattices. The dynamics is analyzed after a sudden switch-on or switch-off of a superlattice potential, which can bring the system into insulating or superfluid phases, respectively. A collapse and revival of the zero-momentum peak can be seen in the first case. We study in detail the relaxation of these integrable systems towards equilibrium. We show that after relaxation time averages of physical observables, like the momentum distribution function, can be predicted by means of a generalization of the Gibbs distribution. [M. Rigol, A. Muramatsu, and M. Olshanii, Phys. Rev. A 74, 053616 (2006).
Superfluid kinetic equation approach to the dynamics of the 3He A-B phase boundary
International Nuclear Information System (INIS)
Palmeri, J.
1990-01-01
The dynamics of the A-B phase boundary is studied using a nonequilibrium theory inspired by the microscopic approach to flux flow in type-II superconductors, namely a generalized two-fluid model consisting of coupled dynamical equations for the superfluid order parameter and the quasiparticle fluid. The interface mobility is obtained to lowest order in the front velocity in three different dynamical regimes: the gapless, hydrodynamic, and ballistic. Experiments have so far only been performed in the ballistic regime, and in this regime we find that, if only Andreev scattering processes are accounted for in the interface mobility, then the theoretical predictions for the terminal velocity of the planar interface are too big by a factor ∼2. From this we conclude that there may be other important contributions to the interface mobility in the ballistic regime, and we discuss a few possibilities
PIP-II Cryogenic System and the evolution of Superfluid Helium Cryogenic Plant Specifications
Chakravarty, Anindya; Rane, Tejas; Klebaner, Arkadiy
2017-12-01
The PIP-II cryogenic system consists of a Superfluid Helium Cryogenic Plant (SHCP) and a Cryogenic Distribution System (CDS) connecting the SHCP to the Superconducting (SC) Linac consisting of 25 cryomodules. The dynamic heat load of the SC cavities for continuous wave (CW) as well as pulsed mode of operation are determined. The static heat loads of the cavities along with the CDS are discussed. The supercritical helium (SHe) flow requirements for each cryomodule are computed through simulation study. Comparison between the flow requirements of the cryomodules for the CW and pulsed modes of operation are made. From the total computed heat load and pressure drop values in the CDS, the basic specifications for the SHCP, required for cooling the SC Linac, have evolved.
High resolution measurements of the temperature dependence of the roton energy of superfluid 4He
International Nuclear Information System (INIS)
Pearce, J.V.; Azuah, R.T.; Stirling, W.G.
1999-01-01
Complete text of publication follows. Recent neutron inelastic scattering measurements [1] at the ILL (energy resolution 4 He roton energy on temperature have shown significant deviations from the expected behaviour; the temperature variation was found to be slower than predicted by the established roton-roton interaction theory due to Bedel, Pines and Zawadowski [2] (BPZ). New measurements of the roton excitations in superfluid 4 He have been made using the IRIS spectrometer (energy resolution ∼ 20 μeV) at the ISIS spallation neutron source. The roton energy was determined over a temperature range of 0.5 K to 1.6 K. It was found that the results can be described well by the BPZ theory and so appear to contradict the ILL results. (author)
Noiseless film boiling in superfluid helium on a heated thin (32 micron) wire
International Nuclear Information System (INIS)
Jebali, F.; Maza, J.; Francois, M.X.; Vidal, F.
1988-01-01
Results are presented on the heat transfer in superfluid helium for a heat flux density range high enough to locally evaporate the liquid. In the present paper, the case of a thin wire heater (32 micron) placed horizontally in the helium bath is focused on. Also, the scenario presented here will be the noiseless (stable) film boiling. For a given vapor film (constant thickness), the experimental dependence of the heat flux density at the vapor-liquid interface as a function of the hydrostatic pressure, and of the heater temperature as a function of the heat flux density at the surface heater is presented. These experimental results will be analyzed using irreversible thermodynamics theories and kinetic approaches. 17 references
Extraordinary sensitivity of the internal Doppler effect in a superfluid 4-3He admixture
Nepomnyashchy, Y. A.; Gov, N.; Mann, A.; Revzen, M.
1995-09-01
Recently, a nontrivial T (temperature) behavior was found for the Doppler shift of the fourth and first sounds in superfluid 4He with internal motion: a plateau in the phonon region and a sharp peak in the beginning of the roton region of the Doppler parameters Γ4,1 (T)=(Δu4,1/vs)v=0. The situation is similar to the case of second sound investigated long ago for Γ2(T)=(Δu2/vn)v=0, but the signs and values of plateaus and peaks indicated some kinds of Doppler anomalies: the ``outstripping effect'' (OEF), in addition to the ``back-entrainment effect'' (BEF) described by Khalatnikov (Δui is the Doppler shift of ith sound; vs, vn, v are the velocities of superfluid and normal components and of the liquid as a whole, respectively). The Doppler anomalies mean the breaking of some ``natural'' suppositions: that Δui is intermediate between vn and vs, and that the sign of (Δui-v) is determined by the velocity of the ``dominant'' component (at low T this is the superfluid component for first and fourth sounds, vd=vs, and the normal one for second sound, vd=vn). The direction of (Δui-v) can be opposite to the direction of (vd-v) (BEF) and the center of spreading sound can move faster than the flowing dominant component when the other component is stationary: Δui>vd (OEF). The Doppler anomalies as well as the very existence of the nonkinematic (internal) Doppler shift Δui-v≠0, and its nontrivial T behavior are special manifestations of the superfluidity. Here we investigate the Doppler phenomenon in the 4-3He mixture. We find strong sensitivity of the T behavior of the Doppler shift and of the Doppler anomalies to the 3He admixture. At low T this is associated with a general peculiarity of the 4-3He mixture: the nonanalyticity of its characteristics, i.e., the inequivalence of T-->0, X-->0 to X-->0, T-->0 (X is the concentration of 3He). We find some ``key derivatives:'' ∂ρ/∂w2, ∂σ/∂w2, crucial for the T behavior of Γi whose role changes at X≠0 (ρ and
Superfluidity of a dipolar Fermi gas in 2D optical lattices bilayer
Energy Technology Data Exchange (ETDEWEB)
Camacho-Guardian, A.; Paredes, R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico (Mexico)
2016-12-15
Ultracold Fermi molecules lying in 2D square optical lattices bilayers with its dipole moment perpendicularly aligned to the layers, having interlayer finite range s-wave interactions, are shown to form superfluid phases, both, in the Bardeen, Cooper and Schrieffer (BCS) regime of Cooper pairs, and in the condensate regime of bound dimeric molecules. We demonstrate this result using a functional integral scheme within the Ginzburg-Landau theory. For the deep Berezinskii-Kosterlitz-Thouless (BKT) phase transition, we predict critical temperatures around 5 nK and 20 nK for {sup 23}Na{sup 40}K and OH molecules, which are within reach of current experiments [J. W. Park, S. Will and M. Zwierlein, Phys. Rev. Lett. 114, 205302 (2015)]. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Applied string theory, hot and cold. A holographic view on quark-gluon plasma and superfluids
Energy Technology Data Exchange (ETDEWEB)
Samberg, Andreas Wilhelm
2015-12-21
This thesis deals with applications of gauge/gravity duality to strong-coupling phenomena in the quark-gluon plasma and far-from-equilibrium superfluids. In a first part we search for model-independent (universal) behavior in various non-Abelian gauge-theory plasmas at finite temperature and chemical potential. We employ the holographic duals of strongly coupled N=4 supersymmetric Yang-Mills theory and three one-parameter families of non-conformal deformations thereof, two of which solve the equations of motion of a five-dimensional Einstein-Maxwell-scalar action. We study the free energy and associated thermodynamic quantities of heavy quarks and bound quark-anti-quark (Q anti Q) pairs as well as the Q anti Q binding energy and the running coupling. We find qualitative agreement with available lattice QCD data. Moreover, we show that several observables exhibit universal behavior for all values of the chemical potential. In a second part we investigate the real-time dynamics of a bosonic superfluid in two spatial dimensions after initial quenches that take the system to far-from-equilibrium states characterized by many topological vortex defects in association with quantum turbulence. To this end we numerically solve the full equations of motion of the holographically dual Abelian Higgs model on four-dimensional anti-de Sitter space. We observe a universal non-equilibrium late-time regime characterized by power-law behavior in a two-point correlation function and in characteristic length scales, which we interpret as a non-thermal fixed point.
Dynamics of vortex tangle without mutual friction in superfluid 4He
International Nuclear Information System (INIS)
Tsubota, Makoto; Araki, Tsunehiko; Nemirovskii, Sergey K.
2000-01-01
A recent experiment has shown that a tangle of quantized vortices in superfluid 4 He decayed even at mK temperatures where the normal fluid was negligible and no mutual friction worked. Motivated by this experiment, this work studies numerically the dynamics of the vortex tangle without the mutual friction, thus showing that a self-similar cascade process, whereby large vortex loops break up to smaller ones, proceeds in the vortex tangle and is closely related with its free decay. This cascade process which may be covered with the mutual friction at higher temperatures is just the one at zero temperature Feynman proposed long ago. The full Biot-Savart calculation is made for dilute vortices, while the localized induction approximation is used for a dense tangle. The former finds the elementary scenario: the reconnection of the vortices excites vortex waves along them and makes them kinked, which could be suppressed if the mutual friction worked. The kinked parts reconnect with the vortex they belong to, dividing into small loops. The latter simulation under the localized induction approximation shows that such cascade process actually proceeds self-similarly in a dense tangle and continues to make small vortices. Considering that the vortices of the interatomic size no longer keep the picture of vortex, the cascade process leads to the decay of the vortex line density. The presence of the cascade process is supported also by investigating the classification of the reconnection type and the size distribution of vortices. The decay of the vortex line density is consistent with the solution of the Vinen's equation which was originally derived on the basis of the idea of homogeneous turbulence with the cascade process. The cascade process revealed by this work is an intrinsic process in the superfluid system free from the normal fluid. The obtained result is compared with the recent Vinen's theory which discusses the Kelvin wave cascade with sound radiation
Phonon contribution to the shear viscosity of a superfluid Fermi gas in the unitarity limit
International Nuclear Information System (INIS)
Mannarelli, Massimo; Manuel, Cristina; Tolos, Laura
2013-01-01
We present a detailed analysis of the contribution of small-angle Nambu–Goldstone boson (phonon) collisions to the shear viscosity, η, in a superfluid atomic Fermi gas close to the unitarity limit. We show that the experimental values of the shear viscosity coefficient to entropy ratio, η/s, obtained at the lowest reached temperature can be reproduced assuming that phonons give the leading contribution to η. The phonon contribution is evaluated considering 1↔2 processes and taking into account the finite size of the experimental system. In particular, for very low temperatures, T≲0.1T F , we find that phonons are ballistic and the contribution of phonons to the shear viscosity is determined by the processes that take place at the interface between the superfluid and the normal phase. This result is independent of the detailed form of the phonon dispersion law and leads to two testable predictions: the shear viscosity should correlate with the size of the optical trap and it should decrease with decreasing temperature. For higher temperatures the detailed form of the phonon dispersion law becomes relevant and, within our model, we find that the experimental data for η/s can be reproduced assuming that phonons have an anomalous dispersion law. -- Highlights: •We study the contribution of phonons to shear viscosity of a cold Fermi gas at unitary. •The shear viscosity to entropy ratio (η/s) is reproduced for T F . •For very low temperatures η/s correlates with the size of the optical trap. •We explain η/s for T>∼0.1T F assuming an anomalous dispersion law for phonons
Rydberg States of Alkali Metal Atoms on Superfluid Helium Droplets - Theoretical Considerations
Pototschnig, Johann V.; Lackner, Florian; Hauser, Andreas W.; Ernst, Wolfgang E.
2017-06-01
The bound states of electrons on the surface of superfluid helium have been a research topic for several decades. One of the first systems treated was an electron bound to an ionized helium cluster. Here, a similar system is considered, which consists of a helium droplet with an ionized dopant inside and an orbiting electron on the outside. In our theoretical investigation we select alkali metal atoms (AK) as central ions, stimulated by recent experimental studies of Rydberg states for Na, Rb, and Cs attached to superfluid helium nanodroplets. Experimental spectra , obtained by electronic excitation and subsequent ionization, showed blueshifts for low lying electronic states and redshifts for Rydberg states. In our theoretical treatment the diatomic AK^+-He potential energy curves are first computed with ab initio methods. These potentials are then used to calculate the solvation energy of the ion in a helium droplet as a function of the number of atoms. Additional potential terms, derived from the obtained helium density distribution, are added to the undisturbed atomic pseudopotential in order to simulate a 'modified' potential felt by the outermost electron. This allows us to compute a new set of eigenstates and eigenenergies, which we compare to the experimentally observed energy shifts for highly excited alkali metal atoms on helium nanodroplets. A. Golov and S. Sekatskii, Physica B, 1994, 194, 555-556 E. Loginov, C. Callegari, F. Ancilotto, and M. Drabbels, J. Phys. Chem. A, 2011, 115, 6779-6788 F. Lackner, G. Krois, M. Koch, and W. E. Ernst, J. Phys. Chem. Lett., 2012, 3, 1404-1408 F. Lackner, G. Krois, M. Theisen, M. Koch, and W. E. Ernst, Phys. Chem. Chem. Phys., 2011, 13, 18781-18788
Applied string theory, hot and cold. A holographic view on quark-gluon plasma and superfluids
International Nuclear Information System (INIS)
Samberg, Andreas Wilhelm
2015-01-01
This thesis deals with applications of gauge/gravity duality to strong-coupling phenomena in the quark-gluon plasma and far-from-equilibrium superfluids. In a first part we search for model-independent (universal) behavior in various non-Abelian gauge-theory plasmas at finite temperature and chemical potential. We employ the holographic duals of strongly coupled N=4 supersymmetric Yang-Mills theory and three one-parameter families of non-conformal deformations thereof, two of which solve the equations of motion of a five-dimensional Einstein-Maxwell-scalar action. We study the free energy and associated thermodynamic quantities of heavy quarks and bound quark-anti-quark (Q anti Q) pairs as well as the Q anti Q binding energy and the running coupling. We find qualitative agreement with available lattice QCD data. Moreover, we show that several observables exhibit universal behavior for all values of the chemical potential. In a second part we investigate the real-time dynamics of a bosonic superfluid in two spatial dimensions after initial quenches that take the system to far-from-equilibrium states characterized by many topological vortex defects in association with quantum turbulence. To this end we numerically solve the full equations of motion of the holographically dual Abelian Higgs model on four-dimensional anti-de Sitter space. We observe a universal non-equilibrium late-time regime characterized by power-law behavior in a two-point correlation function and in characteristic length scales, which we interpret as a non-thermal fixed point.
International Nuclear Information System (INIS)
Alvarez R, J.T.
1998-01-01
This thesis presents a microscopic model for the non-linear fluctuating hydrodynamic of superfluid helium ( 4 He), model developed by means of the Maximum Entropy Method (Maxent). In the chapter 1, it is demonstrated the necessity to developing a microscopic model for the fluctuating hydrodynamic of the superfluid helium, starting from to show a brief overview of the theories and experiments developed in order to explain the behavior of the superfluid helium. On the other hand, it is presented the Morozov heuristic method for the construction of the non-linear hydrodynamic fluctuating of simple fluid. Method that will be generalized for the construction of the non-linear fluctuating hydrodynamic of the superfluid helium. Besides, it is presented a brief summary of the content of the thesis. In the chapter 2, it is reproduced the construction of a Generalized Fokker-Planck equation, (GFP), for a distribution function associated with the coarse grained variables. Function defined with aid of a nonequilibrium statistical operator ρhut FP that is evaluated as Wigneris function through ρ CG obtained by Maxent. Later this equation of GFP is reduced to a non-linear local FP equation from considering a slow and Markov process in the coarse grained variables. In this equation appears a matrix D mn defined with a nonequilibrium coarse grained statistical operator ρhut CG , matrix elements are used in the construction of the non-linear fluctuating hydrodynamics equations of the superfluid helium. In the chapter 3, the Lagrange multipliers are evaluated for to determine ρhut CG by means of the local equilibrium statistical operator ρhut l -tilde with the hypothesis that the system presents small fluctuations. Also are determined the currents associated with the coarse grained variables and furthermore are evaluated the matrix elements D mn but with aid of a quasi equilibrium statistical operator ρhut qe instead of the local equilibrium operator ρhut l -tilde. Matrix
Regnier, David; Lacroix, Denis; Scamps, Guillaume; Hashimoto, Yukio
2018-03-01
In a mean-field description of superfluidity, particle number and gauge angle are treated as quasiclassical conjugated variables. This level of description was recently used to describe nuclear reactions around the Coulomb barrier. Important effects of the relative gauge angle between two identical superfluid nuclei (symmetric collisions) on transfer probabilities and fusion barrier have been uncovered. A theory making contact with experiments should at least average over different initial relative gauge-angles. In the present work, we propose a new approach to obtain the multiple pair transfer probabilities between superfluid systems. This method, called phase-space combinatorial (PSC) technique, relies both on phase-space averaging and combinatorial arguments to infer the full pair transfer probability distribution at the cost of multiple mean-field calculations only. After benchmarking this approach in a schematic model, we apply it to the collision 20O+20O at various energies below the Coulomb barrier. The predictions for one pair transfer are similar to results obtained with an approximated projection method, whereas significant differences are found for two pairs transfer. Finally, we investigated the applicability of the PSC method to the contact between nonidentical superfluid systems. A generalization of the method is proposed and applied to the schematic model showing that the pair transfer probabilities are reasonably reproduced. The applicability of the PSC method to asymmetric nuclear collisions is investigated for the 14O+20O collision and it turns out that unrealistically small single- and multiple pair transfer probabilities are obtained. This is explained by the fact that relative gauge angle play in this case a minor role in the particle transfer process compared to other mechanisms, such as equilibration of the charge/mass ratio. We conclude that the best ground for probing gauge-angle effects in nuclear reaction and/or for applying the proposed
Transition from a 2D Degenerate Bose Liquid to 3D Superfluid in 4He Films Formed in Nanopores
Matsushita, Taku; Hieda, Mitsunori; Toda, Ryo; Inagaki, Shinji; Wada, Nobuo
2017-10-01
The phase transition mechanism in a new dimensional condition was studied for the 4He film formed in 3D nanopore where pores of 2.7 nm diameter are connected in 3D with a period of 5.5 nm. In the case of a very low superfluid onset temperature TSF at a low coverage, a sharp and large peak of the specific heat indicates the typical 3D transition of the 4He film. This is understood by comparing the relative lengths among the 3D and 2D mean atomic distances and the 3D connection length of the film. When the coverage is increased, these length relations are changed to a new dimensional condition. We observed a sharp peak at TSF of the 3D transition up to 1.1 K. For a thick film, we also observed a hump at TB, which is higher than TSF. The hump is attributed to a phase change to a 2D degenerate state with a finite amplitude but without a long range order in the phase of superfluid order parameters. This indicates a new type of transition at TSF from the 2D degenerate state to the 3D superfluid, which is essentially different from the Kosterlitz-Thouless transition.
Proceedings of the solid state physics symposium. Vol. 34C
International Nuclear Information System (INIS)
1991-12-01
This volume contains the proceedings of the Solid State Physics Symposium held at Varanasi during December 21 to 24, 1991. The topics discussed in the symposium were : (a) Phonon physics, (b) Electron states and electronic properties, (c) Magnetism and magnetic properties, (d) Semiconductor physics, (e) Physics of defects and disordered materials, (f) Transport properties, (g) Superconductivity and superfluidity, (h) Liquid crystals and plastic crystals, (i) Phase transitions and critical phenomena, (j) Surface and interface physics, (k) Non-linear dynamics, instabilities and chaos, (l) Resonance studies and relaxation phenomena, (m) Solid state devices, techniques and instrumentation. Three seminars on topics : (i) High T c superconductors, (ii) Soft matter, and (iii) Physics and technology of interfaces were also held during the symposium. (M.K.V.N.)
Verification of an analytic fit for the vortex core profile in superfluid Fermi gases
Energy Technology Data Exchange (ETDEWEB)
Verhelst, Nick, E-mail: nick.verhelst@uantwerpen.be [TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen (Belgium); Klimin, Serghei, E-mail: sergei.klimin@uantwerpen.be [TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen (Belgium); Department of Theoretical Physics, State University of Moldova, Republic of Moldova (Moldova, Republic of); Tempere, Jacques [TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610 Antwerpen (Belgium); Lyman Laboratory of Physics, Harvard University (United States)
2017-02-15
Highlights: • The vortex profile in an imbalanced Fermi condensate is investigated. • The analytic fit for the vortex profile is compared with numerical simulations. • The analytic fit excellently agrees with numeric results in the BCS-BEC crossover. - Abstract: A characteristic property of superfluidity and -conductivity is the presence of quantized vortices in rotating systems. To study the BEC-BCS crossover the two most common methods are the Bogoliubov-De Gennes theory and the usage of an effective field theory. In order to simplify the calculations for one vortex, it is often assumed that the hyperbolic tangent yields a good approximation for the vortex structure. The combination of a variational vortex structure, together with cylindrical symmetry yields analytic (or numerically simple) expressions. The focus of this article is to investigate to what extent this analytic fit truly reflects the vortex structure throughout the BEC-BCS crossover at finite temperatures. The vortex structure will be determined using the effective field theory presented in [Eur. Phys. Journal B 88, 122 (2015)] and compared to the variational analytic solution. By doing this it is possible to see where these two structures agree, and where they differ. This comparison results in a range of applicability where the hyperbolic tangent will be a good fit for the vortex structure.
Utilizing subcooled, superfluid He-II in the design of a 12-Tesla tandem mirror experiment
International Nuclear Information System (INIS)
Hoard, R.W.; Cornish, D.N.; Baldi, R.W.; Taylor, W.D.
1981-01-01
A design study of 12-T yin-yang coils for a conceptual Tandem Mirror Next Step facility has been recently performed by Lawrence Livermore National Laboratory in conjunction with the Convair Division of General Dynamics. The large magnets have major and mirror radii of 3.7 and 1.5 m, 0.70 x 3.75 m 2 cross section, 46.3 MA turns, and an overall current density of 1765 A/cm 2 , obtained by the use of Nb 3 Sn and Nb-Ti superconductors. Each coil is composed of several subcoils separated by internal strengthening substructure to react the enormous electromagnetic forces. The size of the yin-yang coils, and hence the current density, was reduced by utilizing subcooled, superfluid He-II at 1.8 K for the coolant. This paper reviews the design study, with emphasis on He-II heat transport and conductor stability. Methods are also presented which allow the extension of Gorter-Mellink-channel calculations to encompass multiple, interconnecting coolant channels
Design of 12-T Yin-Yang magnets operating in subcooled, superfluid helium
International Nuclear Information System (INIS)
Cornish, D.N.; Hoard, R.W.; Baldi, R.
1981-01-01
A conceptual design study of a large 12-T yin-yang pair of coils, typical of the plug coils envisioned for a tandem-mirror facility to follow MFTF, has been completed. Because of its larger size and field strength, the magnetic forces are much greater than those experienced on MFTF. The main purpose of this study, therefore, is to assess the feasibility of such a device, paying particular attention to mechanical stress and conductor strain. The conductor proposed operates at 15.6 kA and consists of a rectangular half-hard copper stabilizer with a Nb-Ti insert in the low-field regions and Nb 3 Sn in the high field. The coil is divided into four sections in the longitudinal direction, with steel substructure to limit the winding stress to an acceptable level. The conductor is cryostatically stabilized in superfluid He at 1.8K and 1.2 atm, with an operating heat flux of 0.8 W.cm -2
Neutron spin echo investigation of elementary excitations in superfluid 4He
International Nuclear Information System (INIS)
Mezei, F.
1980-01-01
The present work represents the first experimental evidence for the application of Neutron Spin Echo (NSE) in high resolution study of both optical-like (non dispersive) and dispersive elementary excitations. The results obtained proved to be relevant contributions concerning the temperature dependence of the energy and linewidth of the roton excitation between 0.96 and 1.4 K; the temperature dependence of the linewidth of the 1.1 A -1 and 1.72 A -1 phonons and the suggested onset of three-phonon decay between 2.1 A -1 and 2.4 A -1 . The energy transfer resolution achieved in this work was 10-40 times superiour to those in previous similar neutron scattering experiments. In this paper most of the attention will be paid to the experimental aspects. In the first section the details of the NSE experiment are described, with particular emphasis on the first demonstration of the general scheme of NSE focussing, which involves the tuning of both the ratio of the precession fields H 0 /H 1 and their geometrical assymetry ('tilt angle'). The second section gives the experimental results without, however, a detailed discussion of their significance for the understanding of superfluid 4 He, which will be published elsewhere. (orig.)
International Nuclear Information System (INIS)
Johnson, R.S.
1984-01-01
The propagation of surface waves - that is 'third' sound -on superfluid helium is considered. The fluid is treated as a continuum, using the two-fluid model of Landau, and incorporating the effects of healing, relaxation, thermal conductivity and Newtonian viscosity. A linear theory is developed which includes some discussion of the matching to the outer regions of the vapour. This results in a comprehensive propagation speed for linear waves, although a few properties of the flow are left undetermined at this order. A nonlinear theory is then outlined which leads to the Burgers equation in an appropriate far field, and enables the leading-order theory to be concluded. Some numerical results, for two temperatures, are presented by first recording the Helmholtz free energy as a polynomial in densities, but only the equilibrium state can be satisfactorily reproduced. The propagation speed, as a function of film thickness, is roughly estimated. The looked-for reduction in the predicted speeds is evident, but the magnitude of this reduction is too large for very thin films. However, these analytical results should prove more effective when a complete and accurate description of the Helmholtz free energy is available. (author)
A Facility for Accurate Heat Load and Mass Leak Measurements on Superfluid Helium Valves
Bézaguet, Alain-Arthur; Ferlin, G; Losserand-Madoux, R; Perin, A; Vandoni, Giovanna; Van Weelderen, R
1999-01-01
The superconducting magnets of the Large Hadron Collider (LHC) will be protected by safety relief valves operating at 1.9 K in superfluid helium (HeII). A test facility was developed to precisely determine the heat load and the mass leakage of cryogenic valves with HeII at their inlet. The temperature of the valve inlet can be varied from 1.8 K to 2 K for pressures up to 3.5 bar. The valve outlet pipe temperature can be regulated between 5 K and 20 K. The heat flow is measured with high precision using a Kapitza-resistance heatmeter and is also crosschecked by a vaporization measurement. After calibration, a precision of 10 mW for heat flows up to 1.1 W has been achieved. The helium leak can be measured up to 15 mg/s with an accuracy of 0.2 mg/s. We present a detailed description of the test facility and the measurements showing its performances.
Vortex loops in the critical Casimir effect in superfluid and superconducting films
International Nuclear Information System (INIS)
Williams, Gary A.
2004-01-01
Vortex-loop renormalization techniques are used to calculate the magnitude of the critical Casimir forces in superfluid and superconducting thin films. The force is found to become appreciable when the size of the thermally excited vortex loops is comparable to the film thickness, and the results for T c are found to match very well with perturbative renormalization-group theories that can only be carried out for T>T c . In helium films the Casimir force leads to a change in the film thickness close to T c that has been observed experimentally. A similar effect is predicted to occur near the transition temperature of high-T c superconducting films, which is also a vortex-loop phase transition. In this case the Casimir force takes the form of a voltage difference that will appear at the junction between a thin film and a bulk sample. Estimates show that this voltage can be appreciable (tens of microvolts), and it may be possible to observe the effect by measuring the voltage across two Josephson tunnel junctions to the film and to the bulk, using a SQUID voltmeter
Energy Technology Data Exchange (ETDEWEB)
Yang, X.F., E-mail: yangxf@ribf.riken.jp [School of Physics, Peking University, Chengfu Road, Haidian District, Beijing 100871 (China); RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Furukawa, T. [Dept. of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397 (Japan); Wakui, T. [Cyclotron and Radioisotope Center Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8578 (Japan); Imamura, K. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Tetsuka, H. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Fujita, T. [Dept. of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Yamaguchi, Y. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Tsutsui, Y. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Mitsuya, Y. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Ichikawa, Y. [Dept. of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro, Tokyo152-8551 (Japan); Ishibashi, Y. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Dept. of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan); Yoshida, N.; Shirai, H. [Dept. of Physics, Tokyo Institute of Technology, 2-12-1 O-Okayama, Meguro, Tokyo152-8551 (Japan); Ebara, Y.; Hayasaka, M. [Dept. of Physics, Tokyo Gakugei University, 4-1-1 Nukuikitamachi, Koganei, Tokyo 184-8501 (Japan); Arai, S.; Muramoto, S. [Dept. of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa 214-8571 (Japan); Hatakeyama, A. [Dept. of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Wada, M.; Sonoda, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); and others
2013-12-15
In order to investigate the structure of exotic nuclei with extremely low yields by measuring nuclear spins and moments, a new laser spectroscopy technique – “OROCHI” (Optical Radioisotopes Observation in Condensed Helium as Ion-catcher) has been proposed in recent years. The feasibility of this technique has been demonstrated by means of a considerable amount of offline and online studies of various atoms in superfluid helium. For in-situ laser spectroscopy of atoms in He II, trapping atoms in the observation region of laser is a key step. Therefore, a method which enables us to trap accelerated atoms at a precise position in He II is highly needed for performing experiment. In this work, a technique making use of a degrader, two plastic scintillators and a photon detection system is established for checking the stopping position of beam based on the LISE++ calculation. The method has been tested and verified by on-line experiments with the {sup 84,85,87}Rb beam. Details of the experimental setup, working procedure and testing results of this method are presented.
Absorption-induced stimulated second-sound scattering in superfluid liquids
International Nuclear Information System (INIS)
Pushkina, N.I.
2006-01-01
A new type of wave interaction for hydrodynamics-absorption-induced stimulated scattering-is considered. The present treatment is particularized to the case of stimulated scattering of second sound in a superfluid. If two waves-an intense pump wave and a signal wave-are propagating in a medium, the power released in the medium, which is proportional to the square modulus of the total field, contains an interference term at the difference frequency of the pump and signal waves. Since the properties of the medium depend on temperature, the temperature inhomogeneities arising at the difference frequency cause scattering of the pump wave, resulting in a field which is resonant for the signal wave. That field is proportional to the absorption coefficient and the intensity of the pump wave. At low intensities of the pump wave such scattering leads to partial compensation of the dissipation of the signal wave, and with increasing intensity of the pump wave it can lead to amplification of the signal wave. This means that stimulated scattering can arise. Analysis of the experimental data suggests that the threshold intensity of this stimulated scattering can be a real experimental quantity
Superfluidity of indirect excitons and biexcitons in coupled quantum wells and superlattices
Lozovik, Yu E; Willander, M
2002-01-01
The collective properties of indirect excitons in coupled quantum wells (CQWs) are considered. The energy of the ground state of the exciton liquid as a function of the density of electrons e and holes h at different separations D between e and h layers is analysed. The quantum gas-liquid transition as D decreases is studied. The superfluidity appearance temperatures in the system (Kosterlitz-Thouless transition temperatures) have been estimated at different separations D between e and h layers. For the anisotropic two-dimensional e-h system in CQWs the Mott metal-insulator quantum transition is considered. The instability of the ground state of the system of interacting two-dimensional indirect excitons in a slab of superlattice with alternating e and h layers is established. The stable system of indirect quasi-two-dimensional biexcitons, consisting of indirect excitons with opposite directed dipole moments, is considered. The radius and the binding energy of the indirect biexciton are calculated. The collec...
International Nuclear Information System (INIS)
Gritsenko, I.A.; Klokol, K.A.; Sokolov, S.S.; Sheshin, G.A.
2016-01-01
An experimental study is made of the drag coefficient, which is the characteristics of energy dissipation during oscillations of the tuning forks, immersed in liquid helium. The experiments were performed in the temperature range from 0.1 to 3.5 K covering both the range of a hydrodynamic flow, and the ballistic regime of transfer of thermal excitations of superfluid helium below 0.6 K. It is found that there is the frequency dependence of the drag coefficient in the hydrodynamic limit, when the main dissipation mechanism is the viscous friction of the fluid against the walls of the oscillating body at temperatures above 0.7 K. In this case, the drag coefficient is proportional to the square root of the frequency of oscillation, and its temperature dependence in He II is determined by the respective dependence of the normal component density of the normal component and the viscosity of the fluid. At lower temperatures, the dependence of drag coefficient on the frequency is not available, and the magnitude of the dissipative losses is determined only by the temperature dependence of the density of the normal component. At the same time in the entire range of temperatures value of dissipative losses depends on the geometry of the oscillating body.
International Nuclear Information System (INIS)
Gleiter, H.
1991-01-01
Nanocrystalline solids are polycrystals, the crystal size of which is a few (typically 1 to 10) nanometres so that 50% or more of the solid consists of incoherent interfaces between crystals of different orientations. Solids consisting primarily of internal interfaces represent a separate class of atomic structures because the atomic arrangement formed in the core of an interface is known to be an arrangement of minimum energy in the potential field of the two adjacent crystal lattices with different crystallographic orientations on either side of the boundary core. These boundary conditions result in atomic structures in the interfacial cores which cannot be formed elsewhere (e.g. in glasses or perfect crystals). Nanocrystalline solids are of interest for the following four reasons: (1) Nanocrystalline solids exhibit an atomic structure which differs from that of the two known solid states: the crystalline (with long-range order) and the glassy (with short-range order). (2) The properties of nanocrystalline solids differ (in some cases by several orders of magnitude) from those of glasses and/or crystals with the same chemical composition, which suggests that they may be utilized technologically in the future. (3) Nanocrystalline solids seem to permit the alloying of conventionally immiscible components. (4) If small (1 to 10 nm diameter) solid droplets with a glassy structure are consolidated (instead of small crystals), a new type of glass, called nanoglass, is obtained. Such glasses seem to differ structurally from conventional glasses. (orig.)
Angelo, Joseph A
2011-01-01
Supported by a generous quantity of full-color illustrations and interesting sidebars, Solid Matter introduces the basic characteristics and properties of solid matter. It briefly describes the cosmic connection of the elements, leading readers through several key events in human pre-history that resulted in more advanced uses of matter in the solid state. Chapters include:. -Solid Matter: An Initial Perspective. -Physical Behavior of Matter. -The Gravity of Matter. -Fundamentals of Materials Science. -Rocks and Minerals. -Metals. -Building Materials. -Carbon Earth's Most Versatile Element. -S
The superfluid diffusion equation S(T)(∂T/∂t) = ∇·[K(T)(∇T)1/3
International Nuclear Information System (INIS)
Dresner, L.
1990-06-01
This report deals with the superfluid diffusion equation, S(T)(∂T/∂t) = ∇·[K(T)(∇T) 1/3 ], which describes heat transport in turbulent helium-II (superfluid helium). Three methods of solution -- the method of similarity, the variational method, and the method of maximum/minimum principles -- are applied to this equation. The solutions discovered are helpful in addressing the use of helium-II in superconducting magnets and other applications. 22 refs., 23 figs., 3 tabs
International Nuclear Information System (INIS)
1995-01-01
The article drawn up within the framework of 'the assessment of the state of the environment in Lebanon' provides an overview of solid waste management, and assesses future wastes volume and waste disposal issues.In particular it addresses the following concerns: - Long term projections of solid waste arisings (i.e. domestic, industrial, such commercial wastes, vehicle types, construction waste, waste oils, hazardous toxic wastes and finally hospital and clinical wastes) are described. - Appropriate disposal routes, and strategies for reducing volumes for final disposal - Balance between municipal and industrial solid waste generation and disposal/treatment and - environmental impacts (aesthetics, human health, natural environment )of existing dumps, and the potential impact of government plans for construction of solid waste facilities). Possible policies for institutional reform within the waste management sector are proposed. Tables provides estimations of generation rates and distribution of wastes in different regions of Lebanon. Laws related to solid waste management are summarized
Massive and modified gravity as self-gravitating media
Ballesteros, Guillermo; Pilo, Luigi
2016-01-01
We study the effective field theory that describes the low-energy physics of self-gravitating media. The field content consists of four derivatively coupled scalar fields that can be identified with the internal comoving coordinates of the medium. Imposing SO(3) internal spatial invariance, the theory describes supersolids. Stronger symmetry requirements lead to superfluids, solids and perfect fluids, at lowest order in derivatives. In the unitary gauge, massive gravity emerges, being thus the result of a continuous medium propagating in spacetime. Our results can be used to explore systematically the effects and signatures of modifying gravity consistently at large distances. The dark sector is then described as a self-gravitating medium with dynamical and thermodynamic properties dictated by internal symmetries. These results indicate that the divide between dark energy and modified gravity, at large distance scales, is simply a gauge choice.
Quantum Spin Ice under a [111] Magnetic Field: From Pyrochlore to Kagome.
Bojesen, Troels Arnfred; Onoda, Shigeki
2017-12-01
Quantum spin ice, modeled for magnetic rare-earth pyrochlores, has attracted great interest for hosting a U(1) quantum spin liquid, which involves spin-ice monopoles as gapped deconfined spinons, as well as gapless excitations analogous to photons. However, the global phase diagram under a [111] magnetic field remains open. Here we uncover by means of unbiased quantum Monte Carlo simulations that a supersolid of monopoles, showing both a superfluidity and a partial ionization, intervenes the kagome spin ice and a fully ionized monopole insulator, in contrast to classical spin ice where a direct discontinuous phase transition takes place. We also show that on cooling, kagome spin ice evolves towards a valence-bond solid similar to what appears in the associated kagome lattice model [S. V. Isakov et al., Phys. Rev. Lett. 97, 147202 (2006)PRLTAO0031-900710.1103/PhysRevLett.97.147202]. Possible relevance to experiments is discussed.
Flux tubes and the type-I/type-II transition in a superconductor coupled to a superfluid
International Nuclear Information System (INIS)
Alford, Mark G.; Good, Gerald
2008-01-01
We analyze magnetic-flux tubes at zero temperature in a superconductor that is coupled to a superfluid via both density and gradient ('entrainment') interactions. The example we have in mind is high-density nuclear matter, which is a proton superconductor and a neutron superfluid, but our treatment is general and simple, modeling the interactions as a Ginzburg-Landau effective theory with four-fermion couplings, including only s-wave pairing. We numerically solve the field equations for flux tubes with an arbitrary number of flux quanta and compare their energies. This allows us to map the type-I/type-II transition in the superconductor, which occurs at the conventional κ≡λ/ξ=1/√(2) if the condensates are uncoupled. We find that a density coupling between the condensates raises the critical κ and, for a sufficiently high neutron density, resolves the type-I/type-II transition line into an infinite number of bands corresponding to 'type-II(n)' phases, in which n, the number of quanta in the favored flux tube, steps from 1 to infinity. For lower neutron density, the coupling creates spinodal regions around the type-I/type-II boundary, in which metastable flux configurations are possible. We find that a gradient coupling between the condensates lowers the critical κ and creates spinodal regions. These exotic phenomena may not occur in nuclear matter, which is thought to be deep in the type-II region but might be observed in condensed-matter systems
Ezoe, Yuichiro; DiPirro, Michael; Fujimoto, Ryuichi; Ishikawa, Kumi; Ishisaki, Yoshitaka; Kanao, Kenichi; Kimball, Mark; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Murakami, Masahide; Noda, Hirofumi; Ohashi, Takaya; Okamoto, Atsushi; Satoh, Yohichi; Sato, Kosuke; Shirron, Peter; Tsunematsu, Shoji; Yamaguchi, Hiroya; Yoshida, Seiji
2018-01-01
When using superfluid helium in low-gravity environments, porous plug phase separators are commonly used to vent boil-off gas while confining the bulk liquid to the tank. Invariably, there is a flow of superfluid film from the perimeter of the porous plug down the vent line. For the soft x-ray spectrometer onboard ASTRO-H (Hitomi), its approximately 30-liter helium supply has a lifetime requirement of more than 3 years. A nominal vent rate is estimated as ˜30 μg/s, equivalent to ˜0.7 mW heat load. It is, therefore, critical to suppress any film flow whose evaporation would not provide direct cooling of the remaining liquid helium. That is, the porous plug vent system must be designed to both minimize film flow and to ensure maximum extraction of latent heat from the film. The design goal for Hitomi is to reduce the film flow losses to exchanger, and knife-edge devices. Design, on-ground testing results, and in-orbit performance are described.
Bielert, Erwin; ten Kate, Herman H.J.; Verweij, A.P.; Verweij, A.P.
2015-01-01
For the luminosity upgrade of the LHC at CERN, the final focusing quadrupole magnets will be exposed to an increased energy deposition in their coil windings. To have a higher heat transfer rate between cable and superfluid helium bath, the cable insulation has been subject of many studies. Improved
Pashitskii, E. A.
1999-02-01
The paradoxes and disparities in the contemporary microscopic theory of superfluid helium (He-II) are discussed along with possible ways of resolving them by taking pair correlations of 4He atoms into consideration. It is shown that most paradoxes are associated with the commonly accepted initial assumption concerning the dominating role of single-particle Bose condensate (SPBC) in the quantum microstructure of the superfluid component ρs. The existence of intensive SPBC leads to a strong hybridization of the elementary excitation branches and to a common dispersion law for all boson branches, which is identified with the quasiparticle spectrum E(p) observed experimentally from slow neutron scattering in liquid helium. However, the stability of this spectrum during a transition through the λ-point and the large value of the gap in the vicinity of the "rotonic" minimum contradict both the Landau theoretical criterion of superfluidity and the small value of experimentally measured critical velocity. At the same time, a strong interaction between particles in the Bose liquid 4He strongly suppresses the SPBC which amounts to less than 1% of all 4He atoms and hence cannot be the main constituent of the superfluid component, unlike the case of a weakly nonideal Bose gas. Moreover, for a quite strong attraction between particles in a certain region of the momentum space, bound pairs of bosons can be formed in the superfluid Bose liquid, and a coherent pair condensate (CPC) analogous to the Cooper pair condensate in superconductors may appear. Such a strong CPC may completely suppress the weak SPBC. In this case, the one-particle spectrum ɛ(p) of elementary excitations does not hybridize with the collective (two-particle) spectrum and does not appear in the structure of the dynamic form factor S(p,ɛ), i.e., does not coincide with the spectrum measured from neutron scattering. The dispersion of one-particle spectrum is defined by the momentum dependence of the pair
Amrit, Jay; Ramiere, Aymeric; Volz, Sebastian
2018-01-01
A quantum solid (solid 4He) in contact with a classical solid defines a new class of interfaces. In addition to its quantum nature, solid 4He is indeed a very plastic medium. We examine the thermal interface resistance upon solidification of superfluid 4He in contact with a silicon crystal surface (111) and show that dislocations play a crucial role in the thermal interface transport. The growth of solid 4He and the measurements are conducted at the minimum of the melting curve of helium (0.778 K and ˜25 bar ). The results display a first-order transition in the Kapitza resistance from a value of RK ,L=(80 ±8 ) c m2K /W at a pressure of 24.5 bar to a value of RK ,S=(41.7 ±8 ) c m2K /W after the formation of solid helium at ˜25.2 bar . The drop in RK ,S is only of a factor of ˜2 , although transverse phonon modes in solid 4He now participate in heat transmission at the interface. We provide an explanation for the measured RK ,S by considering the interaction of thermal phonons with vibrating dislocations in solid 4He. We demonstrate that this mechanism, also called fluttering, induces a thermal resistance RF l∝NdT-6 , where T is the temperature and Nd is the density of dislocations. We estimate that for dislocation densities on the order of ˜107c m-2 , RF l predominates over the boundary resistance RK ,S. These fundamental findings shed light on the role of dislocations and provide a quantitative explanation for previous experiments which showed no measurable change in the Kapitza resistance between Cu and superfluid 4He upon solidification of the latter. This demonstrates the possibility of using dislocations as an additional means to tailor thermal resistances at interfaces, formed especially with a plastic material.
Pietrowicz, S; Canfer, S; Jones, S; Baudouy, B
2011-01-01
In the framework of the European project EuCARD (FP7) aiming at constructing a high magnetic field accelerator magnet of 13 T with Nb3Sn superconducting cables, new electrical insulation are thermally tested. This technology will use “conventional” electrical insulation in combination with pressurized superfluid helium (He II) or saturated helium at atmospheric pressure as coolant. Two composite insulation systems composed of cyanate ester epoxy mix or a tri-functional epoxy (TGPAP-DETDA) with fiberglass tape frame, have been chosen as potential candidates. The knowledge of their thermal properties is necessary for the thermal design and therefore samples have been tested in pressurized He II where heat is applied perpendicularly to the fibers between 1.6 K and 2.0 K. Overall thermal resistance is determined as a function of temperature and the results are compared with other electrical insulation systems used for accelerator magnets.
Santandrea, Dario; Tuccillo, Raffaele; Granieri, Pier Paolo
The heat management is a basic and fundamental aspect of the superconducting magnets used in the CERN Large Hadron Collider. Indeed, the coil temperature must be kept below the critical value, despite the heat which can be generated or deposited in the magnet during the normal operations. Therefore, this thesis work aims at determining the heating power which can be extracted from the superconducting cables of the LHC, specially through their electrical insulation which represents the main thermal barrier. An experimental measurement campaign in superfluid helium bath was performed on several samples reproducting the main LHC magnets. The heating power was generated in the sample by Joule heating and the temperature increase was measured by means of Cernox bare chip and thermocouples. An innovative instrumentation technique which also includes the in-situ calibration of the thermocouples was developed. A thorough uncertainty analysis on the overall measurement chain concluded the experimental setup. The prese...
International Nuclear Information System (INIS)
Kobayashi, Michikazu; Nitta, Muneto
2014-01-01
We study Kelvin modes and translational zero modes excited along a quantized vortex and relativistic global string in superfluids and a relativistic field theory, respectively, by constructing the low-energy effective theory of these modes. We find that they become exact gapless Nambu–Goldstone modes only in a system with the infinite volume limit. On the other hand, in a system with finite volume, we find an imaginary massive gap causing tachyonic instability above some critical wavelength in the relativistic theory. We also find in the non-relativistic theory that Kelvin modes with wavelengths longer than some critical value propagate in the direction opposite to those with shorter length, contrary to conventional understanding. The number of Nambu–Goldstone modes also saturate the equality of the Nielsen–Chadha inequality for both relativistic and non-relativistic theories
Mott insulator–superfluid phase transition in two-band Bose–Hubbard models with gapless nodal lines
Huang, Beibing; Yang, Xiaosen
2018-01-01
Recent studies on ultracold atoms have reported the implementation of laser-assisted tunneling in lattice systems, facilitating the realization of topological phases. Motivated by such advances, we investigate a two-band Bose–Hubbard model with its single-particle energy bands showing gapless nodal lines, which can be realized for ultracold atoms in the cubic optical lattices using laser-assisted tunneling. We analyze the superfluid–Mott insulator (MI) phase transition in this model and obtain a global phase diagram by using the strong-coupling expansion method. The excitation spectra in strong and weak coupling limits inherit the topological properties of single-particle energy bands to show the structures of nodal lines. The topological invariants, the flat surface states and the critical properties are analyzed theoretically in detail. The excitation spectra in the MI and superfluid phases are measurable in ultracold atom experiments to prove our results.
Lebrun, Ph; Tavian, L
2014-01-01
Superfluid helium is increasingly used as a coolant for superconducting devices in particle accelerators: the lower temperature enhances the performance of superconductors in high-field magnets and reduces BCS losses in RF acceleration cavities, while the excellent transport properties of superfluid helium can be put to work in efficient distributed cooling systems. The thermodynamic penalty of operating at lower temperature however requires careful management of the heat loads, achieved inter alia through proper design and construction of the cryostats. A recurrent question appears to be that of the need and practical feasibility of an additional screen cooled by normal helium at around 4.5 K surrounding the cold mass at about 2 K, in such cryostats equipped with a standard 80 K screen. We introduce the issue in terms of first principles applied to the configuration of the cryostats, discuss technical constraints and economical limitations, and illustrate the argumentation with examples taken from large proj...
Iskin, M.
2016-01-01
We consider a two-component Fermi gas with attractive interactions on a square optical lattice, and study the interplay of Zeeman field, spin-orbit coupling, and next-nearest-neighbor hopping on the ground-state phase diagrams in the entire BCS-BEC evolution. In particular, we first classify and distinguish all possible superfluid phases by the momentum-space topology of their zero-energy quasiparticle-quasihole excitations, and then numerically establish a plethora of quantum phase transitions in between. These transitions are further signaled and evidenced by the changes in the corresponding topological invariant of the system, i.e., its Chern number. Lastly, we find that the superfluid phase exhibits a reentrant structure, separated by a fingering normal phase, the origin of which is traced back to the changes in the single-particle density of states.
Energy Technology Data Exchange (ETDEWEB)
Gomes, Clélio B.C., E-mail: cleliogomes@ufrb.edu.br [CETEC, Universidade Federal do Recôncavo da Bahia, 44380-000 Cruz das Almas, Bahia (Brazil); Almeida, Francisco A.G.; Souza, Andre M.C. [Departamento de Fisica, Universidade Federal de Sergipe, 49100-000 Sao Cristovao, Sergipe (Brazil)
2016-04-29
We have studied analytically the Jaynes–Cummings–Hubbard model for a one-dimensional optical lattice with the account of the Kerr-type nonlinearity under the fermionic approximation. We have found that an increase in the number of photons or in the detuning parameter favors the superfluid phase. We have also found that the nonlinear Kerr effect favors the Mott insulator phase, which is in agreement with experimental observations.
Liquid Helium 3 and Solid Helium at Yale and Beyond
Lee, D. M.
2006-03-01
Many of the foundations of low temperature physics in the latter half of the twentieth century were built at Yale University under the leadership of Professor Cecil T. Lane who came to Yale in 1932 and Henry A. Fairbank who obtained his Ph.D. at Yale in 1944 under Lane's guidance. This discussion will mainly treat the contributions of Henry Fairbank and his students during the period between 1954 and 1963, when Henry Fairbank left Yale to become chairman of the Physics Dept. at Duke University. Following World War II small amounts of helium three became available to low temperature experimenters. Henry Fairbank’s graduate students were provided with the opportunity to investigate second sound in dilute and later concentrated mixtures of helium three in superfluid helium four. These measurements showed strong effects of the phase separation in helium 3 - helium 4 mixtures previously discovered in the laboratory of William Fairbank (a student of Lane and a brother of Henry Fairbank). As more helium three became available, studies of pure helium three were performed, including measurements of the thermal conductivity, the density and the specific heat. Early evidence for the melting curve minimum was found. The main emphasis in this work was to search for Fermi liquid behavior. Much of the later work in this area was performed by the group of John Wheatley at the University of Illinois. In studies of solid helium four at Yale, a surprising observation was made. Hitherto it had been thought that hcp was the stable phase throughout the low temperature part of the phase diagram. It was found via ultrasound experiments that a small silver of bcc solid existed at the lowest pressures. While this author was a graduate student at Yale, Henry Fairbank pointed out to him the possibility of cooling helium three via adiabatic compression from the liquid into the solid phase. (Pomeranchuk Cooling). A brief discussion is given of the use of this technique in the discovery of
Reflection and transformation of acoustic waves at the interface in superfluid 3He-A
International Nuclear Information System (INIS)
Kekutiya, Sh.E.; Chkhaidze, N.D.
1997-01-01
Reflection and transformation of acoustic waves in 3 He-A and 3 He-A 1 are considered for two cases: (1) at the boundary with a solid impermeable wall at an arbitrary angle of incidence of a wave and (2) for normal incidence of waves on the interface between a free liquid and a system of periodic plane-parallel capillaries filling the semi-space. For the first case we have calculated the reflection coefficients of the first and the second sounds and spin and spin-temperature waves as well as the coefficients of transformation of these waves into each other. It is shown that the longitudinal wave undergoes no transformation into other waves, there occurs instead its complete reflection from the solid wall. The angle of incidence at which the energy attenuation coefficient of the first sound is maximum, and the interval of angles corresponding to the attenuation and the total interval reflection of the second sound are estimated. For the second case we have obtained: the coefficients of excitation of the fourth sound and the magneto-acoustic wave by the first and the second sounds; the reflection coefficients for the first and the second sounds and the longitudinal spin wave; the coefficient of transformation of the first sound into the second one and vice versa; the coefficient of reflection of the fourth sound from the capillary system - free liquid interface; the coefficient of excitation of longitudinal spin wave in free helium by the same wave in a capillary
Shah, Rehan; Van Gorder, Robert A
2016-03-01
We demonstrate the existence of localized structures along quantized vortex filaments in superfluid helium under the quantum form of the local induction approximation (LIA), which includes mutual friction and normal fluid effects. For small magnitude normal fluid velocities, the dynamics are dissipative under mutual friction. On the other hand, when normal fluid velocities are sufficiently large, we observe parametric amplification of the localized disturbances along quantized vortex filaments, akin to the Donnelly-Glaberson instability for regular Kelvin waves. As the waves amplify they will eventually cause breakdown of the LIA assumption (and perhaps the vortex filament itself), and we derive a characteristic time for which this breakdown occurs under our model. More complicated localized waves are shown to occur, and we study these asymptotically and through numerical simulations. Such solutions still exhibit parametric amplification for large enough normal fluid velocities, although this amplification may be less uniform than would be seen for more regular filaments such as those corresponding to helical curves. We find that large rotational velocities or large wave speeds of nonlinear waves along the filaments will result in more regular and stable structures, while small rotational velocities and wave speeds will permit far less regular dynamics.
Tsepelin, V.; Baggaley, A. Â. W.; Sergeev, Y. Â. A.; Barenghi, C. Â. F.; Fisher, S. Â. N.; Pickett, G. Â. R.; Jackson, M. Â. J.; Suramlishvili, N.
2017-08-01
We present a combined numerical and experimental study of Andreev scattering from quantum turbulence in superfluid 3He-B at ultralow temperatures. We simulate the evolution of moderately dense, three-dimensional, quasiclassical vortex tangles and the Andreev reflection of thermal quasiparticle excitations by these tangles. This numerical simulation enables us to generate the two-dimensional map of local Andreev reflections for excitations incident on one of the faces of a cubic computational domain, and to calculate the total coefficient of Andreev reflection as a function of the vortex line density. Our numerical simulation is then compared with the experimental measurements probing quantum turbulence generated by a vibrating grid. We also address the question of whether the quasiclassical and ultraquantum regimes of quantum turbulence can be distinguished by their respective total Andreev reflectivities. We discuss the screening mechanisms which may strongly affect the total Andreev reflectivity of dense vortex tangles. Finally, we present combined numerical-experimental results for fluctuations of the Andreev reflection from a quasiclassical turbulent tangle and demonstrate that the spectral properties of the Andreev reflection reveal the nature and properties of quantum turbulence.
Chen, Qi-Hui; Li, Peng; Su, Haibin
2016-06-01
By generalizing the traditional single-site strong coupling expansion approach to a cluster one, we study the zero-temperature phase diagram of bosonic atoms in a trimerized Kagomé optical lattice. Some new features are present in this system. Due to the strong intra-trimer hopping interaction, there will be a new Mott insulator (MI), which is by definition incompressible but with a fractional filling per trimer. This is different from the traditional MI, which has an integral filling and originates only from the repulsive interaction between particles. We investigate the MI-to-superfluid transition and the nature of the fractional MI by calculating the critical exponents of phase transitions and the low-lying energy excitation spectra of quasiparticles (quasihole). We will show how the low-energy properties of this system can be understood qualitatively as a Bose-Hubbard model in triangular lattice from the point of view of the cluster strong coupling expansion. We also discuss how our results are related to experiment by studying the Bragg spectroscopy.
Kuma, Susumu; Nakahara, Hiroko; Tsubouchi, Masaaki; Takahashi, Akira; Mustafa, Majd; Sim, Goeun; Momose, Takamasa; Vilesov, Andrey F
2011-06-30
Clusters of tetracene molecules with different numbers of attached (Ar)(N), (Ne)(N) and (H(2))(N) particles (N = 1-2000) are assembled inside superfluid He nanodroplets and studied via laser-induced fluorescence. The frequency shift of the fluorescence spectrum of the tetracene molecules is studied as a function of cluster size and pickup order of tetracene and cluster species. For (Ar)(N) and (Ne)(N) clusters, our results indicate that the tetracene molecules reside inside the clusters when tetracene is captured by the He nanodroplet before the cluster species; conversely, the tetracene molecules stay on the surface of the clusters when tetracene is captured after the cluster species. In the case of (H(2))(N) clusters, however, tetracene molecules reside inside the (H(2))(N) clusters irrespective of the pickup order. We conclude that (Ar)(N) and (Ne)(N) clusters are rigid at T = 0.38 K, while (H(2))(N) clusters of up to N = 2000 remain fluxional at the same temperature. The results may also indicate the occurrence of heterogeneous nucleation of the (H(2))(N) clusters, which is induced by the interaction with tetracene chromophore molecules.
Malecha, Ziemowit; Lubryka, Eliza
2017-11-01
The numerical model of thin layers, characterized by a defined wrapping pattern can be a crucial element of many computational problems related to engineering and science. A motivating example is found in multilayer electrical insulation, which is an important component of superconducting magnets and other cryogenic installations. The wrapping pattern of the insulation can significantly affect heat transport and the performance of the considered instruments. The major objective of this study is to develop the numerical boundary conditions (BC) needed to model the wrapping pattern of thin insulation. An example of the practical application of the proposed BC includes the heat transfer of Rutherford NbTi cables immersed in super-fluid helium (He II) across thin layers of electrical insulation. The proposed BC and a mathematical model of heat transfer in He II are implemented in the open source CFD toolbox OpenFOAM. The implemented mathematical model and the BC are compared in the experiments. The study confirms that the thermal resistance of electrical insulation can be lowered by implementing the proper wrapping pattern. The proposed BC can be useful in the study of new patterns for wrapping schemes. The work has been supported by statutory funds from Polish Ministry for Science and Higher Education for the year of 2017.
Energy Technology Data Exchange (ETDEWEB)
Park, Miok [Korea Institute for Advanced Study, Seoul (Korea, Republic of); Park, Jiwon; Oh, Jae-Hyuk [Hanyang University, Department of Physics, Seoul (Korea, Republic of)
2017-11-15
Einstein-scalar-U(2) gauge field theory is considered in a spacetime characterized by α and z, which are the hyperscaling violation factor and the dynamical critical exponent, respectively. We consider a dual fluid system of such a gravity theory characterized by temperature T and chemical potential μ. It turns out that there is a superfluid phase transition where a vector order parameter appears which breaks SO(3) global rotation symmetry of the dual fluid system when the chemical potential becomes a certain critical value. To study this system for arbitrary z and α, we first apply Sturm-Liouville theory and estimate the upper bounds of the critical values of the chemical potential. We also employ a numerical method in the ranges of 1 ≤ z ≤ 4 and 0 ≤ α ≤ 4 to check if the Sturm-Liouville method correctly estimates the critical values of the chemical potential. It turns out that the two methods are agreed within 10 percent error ranges. Finally, we compute free energy density of the dual fluid by using its gravity dual and check if the system shows phase transition at the critical values of the chemical potential μ{sub c} for the given parameter region of α and z. Interestingly, it is observed that the anisotropic phase is more favored than the isotropic phase for relatively small values of z and α. However, for large values of z and α, the anisotropic phase is not favored. (orig.)
International Nuclear Information System (INIS)
Leung, Kent Kwan Ho
2013-01-01
The development of an Ultra-Cold Neutron (UCN) source at the Institut Laue-Langevin (ILL) based on super-thermal down-scattering of a Cold Neutron (CN) beam in superfluid 4 He is described. A continuous flow, self-liquefying 3 He cryostat was constructed. A beryllium coated prototype converter vessel with a vertical, window-less extraction system was tested on the PF1b CN beam at the ILL. Accumulation measurements with a mechanical valve, and continuous measurements with the vessel left open, were made. The development of a new magnetic UCN trap for neutron lifetime (τ β ) measurements is also described. A 1.2 m long octupole made from permanent magnets, with a bore diameter of 94 mm and surface field of 1.3 T, was assembled. This will be combined with a superconducting coil assembly and used with vertical confinement of UCN by gravity. A discussion of the systematic effects, focussing on the cleaning of above-threshold UCNs, is given. The possibility of detecting the charged decay products is also discussed. UCN storage experiments with the magnetic array and a fomblin-coated piston were performed on PF2 at the ILL. These measurements studied depolarization, spectrum cleaning, and loss due to material reflections in the trap experimentally.
Bisplinghoff, Raymond L; Pian, Theodore HH
2014-01-01
Profusely illustrated exposition of fundamentals of solid mechanics and principles of mechanics, statics, and simple statically indeterminate systems. Covers strain and stress in three-dimensional solids, elementary elasticity, energy principles in solid continuum, and more. 1965 edition.
Campbell, M. E.
1972-01-01
A survey is presented of the most recent developments and trends in the field of solid lubrication. Topics discussed include: a history of solid lubrication, lubricating solids, bonded lubricants, new developments, methods of evaluation, environmental effects, application methods, novel materials, and designs for the use of solid lubricants. Excerpts of solid lubricant specifications and a discussion of contact stresses imposed on specimens in three types of test machines used for the evaluation of solid lubricants are presented.
Theoretical solid state physics
International Nuclear Information System (INIS)
Anon.
1977-01-01
Research activities at ORNL in theoretical solid state physics are described. Topics covered include: surface studies; particle-solid interactions; electronic and magnetic properties; and lattice dynamics
Yixiang, Yu; Sun, Fadi; Ye, Jinwu; Song, Ningfang
We study the global phase diagram of attractively interacting fermions hopping in a square lattice with any linear combinations of Rashba or Dresselhaus spin-orbit coupling (SOC) in a normal Zeeman field. Here, we focus on half filling case. We find there are 3 phases Band insulator, Superfluid (SF) and Topological SF with C =2. The TSF happens in small Zeeman fields and very weak interactions which is the experimentally most easily accessible regimes and has also the smallest heating effects. The transition from the BI to the SF is a first order one due to the multi-minima structure of the energy landscape. There is a topological phase transition from the SF to the TSF at the low critical field h_{c1}, then another one from the TSF to the BI at the upper critical field h_{c2}. We derive effective actions to describe the two topological phase transitions, then study the edge modes and the Majorana zero modes inside a vortex core of the C =2 TSF near both h_{c1}and h_{c2}. We map out the local Berry Curvature distribution near both h_{c1}and h_{c2}. We find a topological tri-critical point along h_{c1}and conjecture that any topological transitions can only be odd order. We also study some bulk-Berry curvature-edge-vortex correspondences. We thank W. M. Liu for encouragements and acknowledge AFOSR FA9550-16-1-0412 for supports.
Braithwaite, E R
1964-01-01
Solid Lubricants and Surfaces deals with the theory and use of solid lubricants, particularly in colloidal form. Portions of this book are devoted to graphite and molybdenum disulfides, which are widely used solid lubricants in colloidal form. An extensive literature on the laboratory examination of hundreds of solids as potential lubricants is also provided in this text. Other topics discussed include the metals and solid lubricants; techniques for examining surfaces; other solid lubricants; metal shaping; and industrial uses of solid-lubricant dispersions. This publication is beneficial to e
Three-body interactions in liquid and solid hydrogen: Evidence from vibrational spectroscopy
Hinde, Robert
2008-03-01
In the cryogenic low-density liquid and solid phases of H2 and D2, the H2 and D2 molecules retain good rotational and vibrational quantum numbers that characterize their internal degrees of freedom. High-resolution infrared and Raman spectroscopic experiments provide extremely sensitive probes of these degrees of freedom. We present here fully-first-principles calculations of the infrared and Raman spectra of liquid and solid H2 and D2, calculations that employ a high-quality six-dimensional coupled-cluster H2-H2 potential energy surface and quantum Monte Carlo treatments of the single-molecule translational degrees of freedom. The computed spectra agree very well with experimental results once we include three-body interactions among the molecules, interactions which we also compute using coupled-cluster quantum chemical methods. We predict the vibrational spectra of liquid and solid H2 at several temperatures and densities to provide a framework for interpreting recent experiments designed to search for superfluid behavior in small H2 droplets. We also present preliminary calculations of the spectra of mixed H2/D2 solids that show how positional disorder affects the spectral line shapes in these systems.
McColgan, Patrick T.; Meraki, Adil; Boltnev, Roman E.; Lee, David M.; Khmelenko, Vladimir V.
2017-04-01
We studied optical and electron spin resonance spectra during destruction of porous structures formed by nitrogen-rare gas (RG) nanoclusters in bulk superfluid helium containing high concentrations of stabilized nitrogen atoms. Samples were created by injecting products of a radio frequency discharge of nitrogen-rare gas-helium gas mixtures into bulk superfluid helium. These samples have a high energy density allowing the study of energy release in chemical processes inside of nanocluster aggregates. The rare gases used in the studies were neon, argon, and krypton. We also studied the effects of changing the relative concentrations between nitrogen and rare gas on thermoluminescence spectra during destruction of the samples. At the beginning of the destructions, α -group of nitrogen atoms, Vegard-Kaplan bands of N_2 molecules, and β -group of O atoms were observed. The final destruction of the samples were characterized by a series bright flashes. Spectra obtained during these flashes contain M- and β -bands of NO molecules, the intensities of which depend on the concentration of molecular nitrogen in the gas mixture as well as the type of rare gas present in the gas mixture.
Burns, Gerald
2013-01-01
Solid State Physics, International Edition covers the fundamentals and the advanced concepts of solid state physics. The book is comprised of 18 chapters that tackle a specific aspect of solid state physics. Chapters 1 to 3 discuss the symmetry aspects of crystalline solids, while Chapter 4 covers the application of X-rays in solid state science. Chapter 5 deals with the anisotropic character of crystals. Chapters 6 to 8 talk about the five common types of bonding in solids, while Chapters 9 and 10 cover the free electron theory and band theory. Chapters 11 and 12 discuss the effects of moveme
Theoretical solid state physics
Haug, Albert
2013-01-01
Theoretical Solid State Physics, Volume 1 focuses on the study of solid state physics. The volume first takes a look at the basic concepts and structures of solid state physics, including potential energies of solids, concept and classification of solids, and crystal structure. The book then explains single-electron approximation wherein the methods for calculating energy bands; electron in the field of crystal atoms; laws of motion of the electrons in solids; and electron statistics are discussed. The text describes general forms of solutions and relationships, including collective electron i
Second-sound studies of coflow and counterflow of superfluid .sup.4./sup.He in channels
Czech Academy of Sciences Publication Activity Database
Varga, E.; Babuin, Simone; Skrbek, L.
2015-01-01
Roč. 27, č. 6 (2015), "065101-1"-"065101-22" ISSN 1070-6631 Institutional support: RVO:68378271 Keywords : rotating flows * turbulent flows * superflow Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.017, year: 2015
Czech Academy of Sciences Publication Activity Database
Babuin, Simone; L'vov, V.S.; Pomyalov, A.; Skrbek, L.; Varga, E.
2016-01-01
Roč. 94, č. 17 (2016), s. 1-18, č. článku 174504. ISSN 2469-9950 Institutional support: RVO:68378271 Keywords : liquid helium-ii * 3-dimensional vortex dynamics * mutual friction * heat current * hydrodynamic turbulence * 2-fluid flow Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016
International Nuclear Information System (INIS)
Wide, L.
1977-01-01
Solid phase coupled antibodies were introduced to facilitate the separation of bound and free labelled ligand in the competitive inhibition radioimmunoassay. Originally, the solid matrix used was in the form of small particles and since then a number of different matrices have been used such as very fine powder particles, gels, paper and plastic discs, magnetic particles and the inside surface of plastic tubes. The coupling of antibodies may be that of a covalent chemical binding, a strong physical adsorbtion, or an immunological binding to a solid phase coupled antigen. New principles of radioimmunoassay such as the solid phase sandwich techniques and the immunoradiometric assay were developped from the use of solid phase coupled antigens and antibodies. The solid phase sandwich techniques are reagent excess methods with a very wide applicability. Several of the different variants of solid phase techniques are suitable for automation. Advantages and disadvantages of solid phase radioimmunoassays when compared with those using soluble reagents are discussed. (orig.) [de
Energy Technology Data Exchange (ETDEWEB)
Epstein, Richard I [Los Alamos National Laboratory; Sheik-bahae, Mansoor [UNM
2008-01-01
We present an overview of solid-state optical refrigeration also known as laser cooling in solids by fluorescence upconversion. The idea of cooling a solid-state optical material by simply shining a laser beam onto it may sound counter intuitive but is rapidly becoming a promising technology for future cryocooler. We chart the evolution of this science in rare-earth doped solids and semiconductors.
International Nuclear Information System (INIS)
Green, P.H.; Watson, D.M.
1989-08-01
This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces
Energy Technology Data Exchange (ETDEWEB)
Green, P.H.; Watson, D.M. (eds.)
1989-08-01
This report contains brief discussions on work done in the Solid State Division of Oak Ridge National Laboratory. The topics covered are: Theoretical Solid State Physics; Neutron scattering; Physical properties of materials; The synthesis and characterization of materials; Ion beam and laser processing; and Structure of solids and surfaces. (LSP)
Solid state radiation dosimetry
International Nuclear Information System (INIS)
Moran, P.R.
1976-01-01
Important recent developments provide accurate, sensitive, and reliable radiation measurements by using solid state radiation dosimetry methods. A review of the basic phenomena, devices, practical limitations, and categories of solid state methods is presented. The primary focus is upon the general physics underlying radiation measurements with solid state devices
Lawrance, R
1972-01-01
Solid State Phenomena explores the fundamentals of the structure and their influence on the properties of solids. This book is composed of five chapters that focus on the electrical and thermal conductivities of crystalline solids. Chapter 1 describes the nature of solids, particularly metals and crystalline materials. This chapter also presents a model to evaluate crystal structure, the forces between atom pairs, and the mechanism of plastic and elastic deformation. Chapter 2 demonstrates random vibrations of atoms in a solid using a one-dimensional array, while Chapter 3 examines the resista
Simonucci, S.; Strinati, G. C.
2014-02-01
We derive a nonlinear differential equation for the gap parameter of a superfluid Fermi system by performing a suitable coarse graining of the Bogoliubov-de Gennes (BdG) equations throughout the BCS-BEC crossover, with the aim of replacing the time-consuming solution of the original BdG equations by the simpler solution of this novel equation. We perform a favorable numerical test on the validity of this new equation over most of the temperature-coupling phase diagram, by an explicit comparison with the full solution of the original BdG equations for an isolated vortex. We also show that the new equation reduces both to the Ginzburg-Landau equation for Cooper pairs in weak coupling close to the critical temperature and to the Gross-Pitaevskii equation for composite bosons in strong coupling at low temperature.
Bielert, E; ten Kate, H
2012-01-01
For a future luminosity upgrade of CERN’s Large Hadron Collider, a drastically improved heat removal in the inner triplet quadrupole magnets is required. One of the necessary improvements involves the cable insulation. A porous all-polyimide insulation scheme has been proposed recently. Essentially the insulation features a network of micro channels filled with superfluid helium that significantly increases the heat transfer through the insulation layer. A three dimensional Finite Element model required to simulate and study the enhanced heat transfer through the micro channels is presented here. The thermal coupling between heated cable and helium as well as the heat flux through the micro-channels are investigated. The model is validated by comparison of results with published measured data. Finally a sensitivity analysis is performed concerning the stability of the cables in magnet windings.
Energy Technology Data Exchange (ETDEWEB)
Furukawa, T; Ishii, Y; Yoshida, N; Nanao, T [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Wakui, T; Sasaki, A; Izumi, S [Cyclotron and Radioisotope Center, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 (Japan); Ichikawa, Y; Yoshimi, A; Wada, M; Sonoda, T [RIKEN Nishina Center, 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan); Tajiri, K [Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043 (Japan); Matsuura, Y; Kato, Y; Yamaguchi, Y; Imamura, K [Department of Physics, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa 214-8571 (Japan); Makuta, M; Hatakeyama, A [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 (Japan); Ito, Y [Department of Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Kobayashi, T, E-mail: takeshi@yap.nucl.ap.titech.ac.jp [RIKEN Advanced Science Institute, 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan)
2011-07-20
We have been developing a new nuclear laser spectroscopic method 'OROCHI' for determining spins and moments of exotic RIs. This is a method based on the combination of superfluid helium as a stopper of radioactive isotope (RI) beam and in-situ laser spectroscopy of RI atoms. This unique method will enable us to measure nuclear spins and electromagnetic moments of extremely low yield RI (less than 1 particle per second). To confirm the feasibility of this method for rare radioisotopes, we carried out the first on-line experiment with a {sup 87}Rb beam, aiming at evaluating the minimum beam intensity required for the measurement. The LIF (Laser Induced Fluorescence) photons from the {sup 87}Rb atoms stopped in He II are successfully observed in the on-line experiment. The obtained LIF intensity is nearly consistent with the intensity calculated from the photo-absorption cross section of atoms in He II.
Ono, Yoshio
2011-01-01
The importance of solid base catalysts has come to be recognized for their environmentally benign qualities, and much significant progress has been made over the past two decades in catalytic materials and solid base-catalyzed reactions. The book is focused on the solid base. Because of the advantages over liquid bases, the use of solid base catalysts in organic synthesis is expanding. Solid bases are easier to dispose than liquid bases, separation and recovery of products, catalysts and solvents are less difficult, and they are non-corrosive. Furthermore, base-catalyzed reactions can be performed without using solvents and even in the gas phase, opening up more possibilities for discovering novel reaction systems. Using numerous examples, the present volume describes the remarkable role solid base catalysis can play, given the ever increasing worldwide importance of "green" chemistry. The reader will obtain an overall view of solid base catalysis and gain insight into the versatility of the reactions to whic...
Magnetic conditioning in superfluid
International Nuclear Information System (INIS)
Caspi, S.
1988-08-01
Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs
Magnetic conditioning in superfluid
Energy Technology Data Exchange (ETDEWEB)
Caspi, S.
1988-08-01
Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs.
Cristol, Y
2013-01-01
Solid State Video Cameras reviews the state of the art in the field of solid-state television cameras as compiled from patent literature. Organized into 10 chapters, the book begins with the basic array types of solid-state imagers and appropriate read-out circuits and methods. Documents relating to improvement of picture quality, such as spurious signal suppression, uniformity correction, or resolution enhancement, are also cited. The last part considerssolid-state color cameras.
Nanoscale hydrodynamics near solids
Camargo, Diego; de la Torre, J. A.; Duque-Zumajo, D.; Español, Pep; Delgado-Buscalioni, Rafael; Chejne, Farid
2018-02-01
Density Functional Theory (DFT) is a successful and well-established theory for the study of the structure of simple and complex fluids at equilibrium. The theory has been generalized to dynamical situations when the underlying dynamics is diffusive as in, for example, colloidal systems. However, there is no such a clear foundation for Dynamic DFT (DDFT) for the case of simple fluids in contact with solid walls. In this work, we derive DDFT for simple fluids by including not only the mass density field but also the momentum density field of the fluid. The standard projection operator method based on the Kawasaki-Gunton operator is used for deriving the equations for the average value of these fields. The solid is described as featureless under the assumption that all the internal degrees of freedom of the solid relax much faster than those of the fluid (solid elasticity is irrelevant). The fluid moves according to a set of non-local hydrodynamic equations that include explicitly the forces due to the solid. These forces are of two types, reversible forces emerging from the free energy density functional, and accounting for impenetrability of the solid, and irreversible forces that involve the velocity of both the fluid and the solid. These forces are localized in the vicinity of the solid surface. The resulting hydrodynamic equations should allow one to study dynamical regimes of simple fluids in contact with solid objects in isothermal situations.
Multivalent ion conducting solids
Energy Technology Data Exchange (ETDEWEB)
Imanaka, N. [Osaka Univ., Suita, Osaka (Japan). Dept. of Applied Chemistry
2008-07-01
Solid electrolytes possess important characteristics for industrial applications. Only a single ionic species can macroscopically migrate in these solids. This paper described a the new NASICON (M-Zr-Nb-P-O) type system, exhibiting an exceptionally high level of trivalent M3+ ion conductivity on polycrystalline solids. The partial substitution of the smaller higher valent Nb5+ ion for Zr4+ stabilized the NASICON phase and realized the M3+ ion conduction in the NASICON structure. It was concluded that the conductivities of the series are comparable to those of the practically applied solid electrolytes of oxide anion conductors of YSZ and CSZ. 3 refs., 2 figs.
International Nuclear Information System (INIS)
Thompson, W.T.; Stinton, L.H.
1980-01-01
Compliance with the latest regulatory requirements addressing disposal of radioactive, hazardous, and sanitary solid waste requires the application of numerous qualitative and quantitative criteria in the selection, design, and operation of solid waste management facilities. Due to the state of flux of these regulatory requirements from EPA and NRC several waste management options were identified as being applicable to the management of the various types of solid waste. This paper highlights the current regulatory constraints and the design and operational requirements for construction of both storage and disposal facilities for use in management of DOE-ORO solid waste. Capital and operational costs are included for both disposal and storage options
Understanding solid state physics
Holgate, Sharon Ann
2009-01-01
Where Sharon Ann Holgate has succeeded in this book is in packing it with examples of the application of solid state physics to technology. … All the basic elements of solid state physics are covered … . The range of materials is good, including as it does polymers and glasses as well as crystalline solids. In general, the style makes for easy reading. … Overall this book succeeds in showing the relevance of solid state physics to the modern world … .-Contemporary Physics, Vol. 52, No. 2, 2011I was indeed amused and inspired by the wonderful images throughout the book, carefully selected by th
Energy Technology Data Exchange (ETDEWEB)
Alvarez R, J.T
1998-10-01
This thesis presents a microscopic model for the non-linear fluctuating hydrodynamic of superfluid helium ({sup 4} He), model developed by means of the Maximum Entropy Method (Maxent). In the chapter 1, it is demonstrated the necessity to developing a microscopic model for the fluctuating hydrodynamic of the superfluid helium, starting from to show a brief overview of the theories and experiments developed in order to explain the behavior of the superfluid helium. On the other hand, it is presented the Morozov heuristic method for the construction of the non-linear hydrodynamic fluctuating of simple fluid. Method that will be generalized for the construction of the non-linear fluctuating hydrodynamic of the superfluid helium. Besides, it is presented a brief summary of the content of the thesis. In the chapter 2, it is reproduced the construction of a Generalized Fokker-Planck equation, (GFP), for a distribution function associated with the coarse grained variables. Function defined with aid of a nonequilibrium statistical operator {rho}hut{sub FP} that is evaluated as Wigneris function through {rho}{sub CG} obtained by Maxent. Later this equation of GFP is reduced to a non-linear local FP equation from considering a slow and Markov process in the coarse grained variables. In this equation appears a matrix D{sub mn} defined with a nonequilibrium coarse grained statistical operator {rho}hut{sub CG}, matrix elements are used in the construction of the non-linear fluctuating hydrodynamics equations of the superfluid helium. In the chapter 3, the Lagrange multipliers are evaluated for to determine {rho}hut{sub CG} by means of the local equilibrium statistical operator {rho}hut{sub l}-tilde with the hypothesis that the system presents small fluctuations. Also are determined the currents associated with the coarse grained variables and furthermore are evaluated the matrix elements D{sub mn} but with aid of a quasi equilibrium statistical operator {rho}hut{sub qe} instead
Universal decoherence in solids.
Chudnovsky, Eugene M
2004-03-26
Symmetry implications for the decoherence of quantum oscillations of a two-state system in a solid are studied. When the oscillation frequency is small compared to the Debye frequency, the universal lower bound on the decoherence due to the atomic environment is derived in terms of the macroscopic parameters of the solid, with no unknown interaction constants.
Buckley, D. H.; Johnson, R. L.
1972-01-01
Brief discussion of the historical background, variety range, chemistry, physics, and other properties of solid lubricants, and review of their current uses. The widespread use of solid lubricants did not occur until about 1947. At present, they are the object of such interest that a special international conference on their subject was held in 1971. They are used at temperatures beyond the useful range of conventional lubricating oils and greases. Their low volatility provides them with the capability of functioning effectively in vacuum and invites their use in space applications. Their high load carrying ability makes them useful with heavily loaded components. Solid lubricants, however, do lack some of the desirable properties of conventional lubricants. Unlike oils and greases, which have fluidity and can continuously be carried back into contact with lubricated surfaces, solid lubricants, because of their immobility, have finite lives. Also, oils and greases can carry away frictional heat from contacting surfaces, while solid lubricants cannot.
Bower, Allan F
2009-01-01
Modern computer simulations make stress analysis easy. As they continue to replace classical mathematical methods of analysis, these software programs require users to have a solid understanding of the fundamental principles on which they are based. Develop Intuitive Ability to Identify and Avoid Physically Meaningless Predictions Applied Mechanics of Solids is a powerful tool for understanding how to take advantage of these revolutionary computer advances in the field of solid mechanics. Beginning with a description of the physical and mathematical laws that govern deformation in solids, the text presents modern constitutive equations, as well as analytical and computational methods of stress analysis and fracture mechanics. It also addresses the nonlinear theory of deformable rods, membranes, plates, and shells, and solutions to important boundary and initial value problems in solid mechanics. The author uses the step-by-step manner of a blackboard lecture to explain problem solving methods, often providing...
Experimental studies in solid state and low temperature physics. Final report for 1966-1980
International Nuclear Information System (INIS)
Goldman, A.M.; Weyhmann, W.V.; Zimmermann, W. Jr.
1980-06-01
Experimental and theoretical investigations have been carried out in a broad area of low temperature and solid state physics which includes superconductivity, theory of quantum crystals (through 1973), magnetism in metals, and liquid helium. The work in superconductivity has involved investigations of the Josephson effect, studies of the pair-field susceptibility of superconductors and investigations of the thermodynamics of the superconducting phase transition. The competition between the metal-nonmetal transition and superconductivity has also been studied in random metal-rare gas systems. In the area of magnetism, magnetically ordered materials and dilute magnetic alloys have been investigated. Enhanced hyperfine nuclear magnetic ordering was discovered in PrCu 6 at about 2.5 mK. The research on liquid 4 He and 3 He/ 4 He mixtures has been directed at the quantum aspects of superfluid flow and rotation, the critical behavior near the lambda transition and the properties of the tricritical point. The theoretical program (through 1973) encompassed a broad spectrum of research on the properties of quantum liquids and solids with particular emphasis on crystalline 3 He
Solid Lithium Ion Conductors (SLIC) for Lithium Solid State Batteries
National Aeronautics and Space Administration — To identify the most lithium-ion conducting solid electrolytes for lithium solid state batteries from the emerging types of solid electrolytes, based on a...
Orton, J W; Walling, J C; Ter Haar, D
1970-01-01
The Solid State Maser presents readings related to solid state maser amplifier from the first tentative theoretical proposals that appeared in the early 1950s to the successful realization of practical devices and their application to satellite communications and radio astronomy almost exactly 10 years later. The book discusses a historical account of the early developments (including that of the ammonia maser) of solid state maser; the properties of paramagnetic ions in crystals; the development of practical low noise amplifiers; and the characteristics of maser devices designed for communica
Nemova, Galina
2009-01-01
Parallel to advances in laser cooling of atoms and ions in dilute gas phase, which has progressed immensely, resulting in physics Nobel prizes in 1997 and 2001, major progress has recently been made in laser cooling of solids. I compare the physical nature of the laser cooling of atoms and ions with that of the laser cooling of solids. I point out all advantages of this new and very promising area of laser physics. Laser cooling of solids (optical refrigeration) at the present time can be lar...
Applications in solid mechanics
DEFF Research Database (Denmark)
Ølgaard, Kristian Breum; Wells, Garth N.
2012-01-01
Problems in solid mechanics constitute perhaps the largest field of application of finite element methods. The vast majority of solid mechanics problems involve the standard momentum balance equation, posed in a Lagrangian setting, with different models distinguished by the choice of nonlinear...... or linearized kinematics, and the constitutive model for determining the stress. For some common models, the constitutive relationships are rather complex. This chapter addresses a number of canonical solid mechanics models in the context of automated modeling, and focuses on some pertinent issues that arise...
Czech Academy of Sciences Publication Activity Database
Čejka, Jiří; Morris, R. E.; Nachtigall, P.; Roth, Wieslaw Jerzy
2014-01-01
Roč. 43, č. 27 (2014), s. 10274-10275 ISSN 1477-9226 Institutional support: RVO:61388955 Keywords : layered inorganic solids * physical chemistry * catalysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.197, year: 2014
National Research Council Canada - National Science Library
Jones, Franklin
2001-01-01
This program was for the design, construction and test of two Solid State Grid Modulators to provide enhanced performance and improved reliability in existing S-band radar transmitters at the Rome Research Site...
Amey, E.B.; Russell, J.A.; Hurdelbrink, R.J.
1996-01-01
In 1976, the U.S. Congress enacted the Resource Conservation and Recovery Act (RCRA) to further address the problem of increasing industrial and municipal waste. The main objectives of RCRA were to responsibly manage hazardous and solid waste and to procure materials made from recovered wastes. To fulfill these objectives, four main programs of waste management were developed. These programs were defined under Subtitle C, the Hazardous Waste Program; Subtitle D, the Solid Waste Program; Subtitle I, the Underground Storage Tank Program; and Subtitle J, the Medical Waste Program. Subtitle D illustrates the solid waste dilemma occurring in the United States. Under this program, states are encouraged to develop and implement their own waste management plans. These plans include the promotion of recycling solid wastes and the closing and upgrading of all environmentally unsound dumps. ?? 1996 International Association for Mathematical Geology.
Solid Waste Management Districts
Vermont Center for Geographic Information — The Solid waste management districts layer is part of a dataset that contains administrative boundaries for Vermont's Agency of Natural Resources. This dataset...
Solids Accumulation Scouting Studies
Energy Technology Data Exchange (ETDEWEB)
Duignan, M. R.; Steeper, T. J.; Steimke, J. L.
2012-09-26
The objective of Solids Accumulation activities was to perform scaled testing to understand the behavior of remaining solids in a Double Shell Tank (DST), specifically AW-105, at Hanford during multiple fill, mix, and transfer operations. It is important to know if fissionable materials can concentrate when waste is transferred from staging tanks prior to feeding waste treatment plants. Specifically, there is a concern that large, dense particles containing plutonium could accumulate in poorly mixed regions of a blend tank heel for tanks that employ mixing jet pumps. At the request of the DOE Hanford Tank Operations Contractor, Washington River Protection Solutions, the Engineering Development Laboratory of the Savannah River National Laboratory performed a scouting study in a 1/22-scale model of a waste staging tank to investigate this concern and to develop measurement techniques that could be applied in a more extensive study at a larger scale. Simulated waste tank solids: Gibbsite, Zirconia, Sand, and Stainless Steel, with stainless steel particles representing the heavier particles, e.g., plutonium, and supernatant were charged to the test tank and rotating liquid jets were used to mix most of the solids while the simulant was pumped out. Subsequently, the volume and shape of the mounds of residual solids and the spatial concentration profiles for the surrogate for heavier particles were measured. Several techniques were developed and equipment designed to accomplish the measurements needed and they included: 1. Magnetic particle separator to remove simulant stainless steel solids. A device was designed and built to capture these solids, which represent the heavier solids during a waste transfer from a staging tank. 2. Photographic equipment to determine the volume of the solids mounds. The mounds were photographed as they were exposed at different tank waste levels to develop a composite of topographical areas. 3. Laser rangefinders to determine the volume of
Schwoerer, Marcus
2007-01-01
This is the first comprehensive textbook on the physical aspects of organic solids. All phenomena which are necessary in order to understand modern technical applications are being dealt with in a way which makes the concepts of the topics accessible for students. The chapters - from the basics, production and characterization of organic solids and layers to organic semiconductors, superconductors and opto-electronical applications - have been arranged in a logical and well thought-out order.
Abraham, Kuzhikalail M.; Alamgir, Mohamed; Choe, Hyoun S.
1995-01-01
This invention relates to Li ion (Li.sup.+) conductive solid polymer electrolytes composed of poly(vinyl sulfone) and lithium salts, and their use in all-solid-state rechargeable lithium ion batteries. The lithium salts comprise low lattice energy lithium salts such as LiN(CF.sub.3 SO.sub.2).sub.2, LiAsF.sub.6, and LiClO.sub.4.
Lyophilization -Solid Waste Treatment
Litwiller, Eric; Flynn, Michael; Fisher, John; Reinhard, Martin
2004-01-01
This paper discusses the development of a solid waste treatment system that has been designed for a Mars transit exploration mission. The technology described is an energy-efficient lyophilization technique that is designed to recover water from spacecraft solid wastes. Candidate wastes include feces, concentrated brines from water processors, and other solid wastes that contain free water. The system is designed to operate as a stand-alone process or to be integrated into the International Space Station Waste Collection System. In the lyophilization process, water in an aqueous waste is frozen and then sublimed, separating the waste into a dried solid material and liquid water. The sublimed water is then condensed in a solid ice phase and then melted to generate a liquid product. In the subject system the waste solids are contained within a 0.2 micron bio-guard bag and after drying are removed from the system and stored in a secondary container. This technology is ideally suited to applications such as the Mars Reference Mission, where water recovery rates approaching 100% are desirable but production of CO2 is not. The system is designed to minimize power consumption through the use of thermoelectric heat pumps. The results of preliminary testing of a prototype system and testing of the final configuration are provided. A mathematical model of the system is also described.
Pietrowicz, S; Jones, S; Canfer, S; Baudouy, B
2012-01-01
In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13 T Nb$_{3}$Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9 K and 1 atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 μm to 598 μm have been tested in steady-state condition in the temperature range of 1.6 K - 2.0 K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k=[(34.2±5.5).T-(16.4±8.2)]×10-3 Wm-1K-1 and for the cyanate ester epoxy k=[(26.8±4.8).T- (9...
International Nuclear Information System (INIS)
Jelatis, G.J.
1983-01-01
Third sound in superfluid helium four films has been investigated using two parallel-plate waveguides. These investigations led to the observation of fifth sound, a new mode of sound propagation. Both waveguides consisted of two parallel pieces of vitreous quartz. The sound speed was obtained by measuring the time-of-flight of pulsed third sound over a known distance. Investigations from 1.0-1.7K were possible with the use of superconducting bolometers, which measure the temperature component of the third sound wave. Observations were initially made with a waveguide having a plate separation fixed at five microns. Adiabatic third sound was measured in the geometry. Isothermal third sound was also observed, using the usual, single-substrate technique. Fifth sound speeds, calculated from the two-fluid theory of helium and the speeds of the two forms of third sound, agreed in size and temperature dependence with theoretical predictions. Nevertheless, only equivocal observations of fifth sound were made. As a result, the film-substrate interaction was examined, and estimates of the Kapitza conductance were made. Assuming the dominance of the effects of this conductance over those due to the ECEs led to a new expression for fifth sound. A reanalysis of the initial data was made, which contained no adjustable parameters. The observation of fifth sound was seen to be consistent with the existence of an anomalously low boundary conductance
Defects in flexoelectric solids
Mao, Sheng; Purohit, Prashant K.
2015-11-01
A solid is said to be flexoelectric when it polarizes in proportion to strain gradients. Since strain gradients are large near defects, we expect the flexoelectric effect to be prominent there and decay away at distances much larger than a flexoelectric length scale. Here, we quantify this expectation by computing displacement, stress and polarization fields near defects in flexoelectric solids. For point defects we recover some well known results from strain gradient elasticity and non-local piezoelectric theories, but with different length scales in the final expressions. For edge dislocations we show that the electric potential is a maximum in the vicinity of the dislocation core. We also estimate the polarized line charge density of an edge dislocation in an isotropic flexoelectric solid which is in agreement with some measurements in ice. We perform an asymptotic analysis of the crack tip fields in flexoelectric solids and show that our results share some features from solutions in strain gradient elasticity and piezoelectricity. We also compute the energy release rate for cracks using simple crack face boundary conditions and use them in classical criteria for crack growth to make predictions. Our analysis can serve as a starting point for more sophisticated analytic and computational treatments of defects in flexoelectric solids which are gaining increasing prominence in the field of nanoscience and nanotechnology.
International Nuclear Information System (INIS)
Anon.
2006-01-01
The European (EU 25) wish to substitute solid biomass origin energy consumption (principally wood and wood waste, but also straw, crop harvest residues, vegetal and animal waste) for a part of that of fossil fuel origin (petrol, gas and coal) is beginning to pay off. 58,7 million tons oil equivalent (Mtoe) of solid biomass was produced in 2005, i.e. a 3.1 Mtoe increase with respect to 2004. Production of primary energy coming from direct combustion of renewable municipal solid waste in incineration plants should also be added on to this figure. The 0,2 Mtoe increase in this production with respect to 2004 brings valorization of this type of waste up to 5,3 Mtoe in 2005. (author)
Fkhir, Moustafa
2016-01-01
Solid bulk cargoes, such as nickel ore and iron ore, have a tendency to liquefy. Such goods can transform from hard to liquid state very rapidly leaving no time for the master or crew to do anything but face their imminent fate. The liquefaction of solid bulk cargoes has claimed many seafarers’ lives and dozens of ships. The moisture content present in these cargoes can be dramatically increased to unsafe limits by the mere reason of the vessel’s rolling on waves. In response to the alarming ...
International Nuclear Information System (INIS)
Reese, M.G.; Johnson, L.R.; Ransom, D.K.
1980-01-01
In a solid phase assay for quantitative determination of biological and other analytes, a sample such as serum is contacted with a receptor for the analyte being assayed, the receptor being supported on a solid support. No tracer for the analyte is added to the sample before contacting with the receptor; instead the tracer is contacted with the receptor after unbound analyte has been removed from the receptor. The assay can be otherwise performed in a conventional manner but can give greater sensitivity. (author)
Photochemistry on solid surfaces
Matsuura, T
1989-01-01
The latest developments in photochemistry on solid surfaces, i.e. photochemistry in heterogeneous systems, including liquid crystallines, are brought together for the first time in a single volume. Distinguished photochemists from various fields have contributed to the book which covers a number of important applications: molecular photo-devices for super-memory, photochemical vapor deposition to produce thin-layered electronic semiconducting materials, sensitive optical media, the control of photochemical reactions pathways, etc. Photochemistry on solid surfaces is now a major field and this
Pridham, G J
2013-01-01
Solid-State Circuits provides an introduction to the theory and practice underlying solid-state circuits, laying particular emphasis on field effect transistors and integrated circuits. Topics range from construction and characteristics of semiconductor devices to rectification and power supplies, low-frequency amplifiers, sine- and square-wave oscillators, and high-frequency effects and circuits. Black-box equivalent circuits of bipolar transistors, physical equivalent circuits of bipolar transistors, and equivalent circuits of field effect transistors are also covered. This volume is divided
Lai, Yun
2011-06-26
Metamaterials can exhibit electromagnetic and elastic characteristics beyond those found in nature. In this work, we present a design of elastic metamaterial that exhibits multiple resonances in its building blocks. Band structure calculations show two negative dispersion bands, of which one supports only compressional waves and thereby blurs the distinction between a fluid and a solid over a finite frequency regime, whereas the other displays super anisotropy-in which compressional waves and shear waves can propagate only along different directions. Such unusual characteristics, well explained by the effective medium theory, have no comparable analogue in conventional solids and may lead to novel applications. © 2011 Macmillan Publishers Limited. All rights reserved.
Directory of Open Access Journals (Sweden)
Zhishan Yuan
2018-02-01
Full Text Available Abstract Solid-state nanopore has captured the attention of many researchers due to its characteristic of nanoscale. Now, different fabrication methods have been reported, which can be summarized into two broad categories: “top-down” etching technology and “bottom-up” shrinkage technology. Ion track etching method, mask etching method chemical solution etching method, and high-energy particle etching and shrinkage method are exhibited in this report. Besides, we also discussed applications of solid-state nanopore fabrication technology in DNA sequencing, protein detection, and energy conversion.
Harrison, Walter A
2011-01-01
""A well-written text . . . should find a wide readership, especially among graduate students."" - Dr. J. I. Pankove, RCA.The field of solid state theory, including crystallography, semi-conductor physics, and various applications in chemistry and electrical engineering, is highly relevant to many areas of modern science and industry. Professor Harrison's well-known text offers an excellent one-year graduate course in this active and important area of research. While presenting a broad overview of the fundamental concepts and methods of solid state physics, including the basic quantum theory o
Wooten, Frederick
1972-01-01
Optical Properties of Solids covers the important concepts of intrinsic optical properties and photoelectric emission. The book starts by providing an introduction to the fundamental optical spectra of solids. The text then discusses Maxwell's equations and the dielectric function; absorption and dispersion; and the theory of free-electron metals. The quantum mechanical theory of direct and indirect transitions between bands; the applications of dispersion relations; and the derivation of an expression for the dielectric function in the self-consistent field approximation are also encompassed.
Directory of Open Access Journals (Sweden)
Sergey G. Chefranov
2014-05-01
Full Text Available Aims The observed experimental and natural phenomenon of cyclone-anticyclone vortex asymmetry implies that a relatively more stable and showing a longer life, as well as a relatively more intense mode of rotation with an anticyclonic circulation direction (opposite to the direction of rotation of the medium as a whole is realized as compared with an oppositely directed rotation of the cyclonic vortex mode. Until now, however, it was not a success to identify a universal triggering mechanism responsible for the formation of the corresponding breaking of chiral vortex symmetry. Materials and methods In this paper we reveal the said linear universal instability mechanism of breaking of chiral symmetry in the sign of vortex circulation in the rotating medium in the presence of linear Eckman friction. Results Obtained is a condition for the linear dissipative - centrifugal instability (DCI, which leads (only when considering the external linear Eckman friction for an abovethreshold value of rotation frequency of the underlying boundary surface of fluid to the breaking of chiral symmetry in the Lagrangian fluid particle dynamics and the corresponding realization of the cyclone-anticyclone vortex asymmetry. Conclusion A new non-stationary solution to the problem for the disc which carries out weak axial-torsional oscillations in fluid with the frequency which are superimposed on its rotation with the previously considered frequency ω0 in connection with the experimental data on the rotating superfluid helium II has been found. It gives the possibility to conclude that the effects of external, linear on velocity, friction forces must be important to include into consideration for the solve of any fundamental problems of hydrodynamics in bounded systems (as for the blood dynamics in cardiovascular system, for example.
Theory of neutron scattering from the two-roton, two-maxon and maxon-roton states in superfluid 4He
International Nuclear Information System (INIS)
Juge, K.J.; Griffin, A.
1994-01-01
In 1970 Ruvalds and Zawadowski (RZ) outlined a microscopic theory of the two-roton pair excitation spectrum in superfluid 4 He. They pointed out that because of a Bose condensate-induced coupling into the density fluctuation spectrum, these pair excitations show up in inelastic neutron data for S(Q,ω) as high energy multiparticle scattering above the maxon-roton quasiparticle peak. Stimulated by recent high-resolution neutron data from ILL, we have carried out an extensive study of the single-particle ρ 1 (Q,ω) and the two-particle ρ 2 (Q,ω) spectral densities within the RZ scenario, over a wide range of wavevectors (1 approx-lt Q approx-lt 3 angstrom -1 ), frequencies and temperatures. We extend the original RZ analysis (which concentrated on the two-roton spectrum) to include the multiparticle structure associated with the maxon-roton and maxon-maxon spectra and present numerical results for both attractive and repulsive quasiparticle interactions. We also point out that the microscopic theory of S(Q,ω), in a Bose-condensed fluid shows that it involves a weighted sum of both ρ 1 (Q,ω) and ρ 2 (Q,ω). As a result, multi-particle structure exhibited by S(Q,ω) is not easily related to theoretical results for ρ 1 (Q,ω) and ρ 2 (Q,ω). Previous attempts in the literature to fit neutron data for S(Q,ω) to either ρ 1 (Q,ω) or ρ 2 (Q,ω) would not appear to have much quantitative basis, especially in the two-roton frequency region ω∼2Δ R
International Nuclear Information System (INIS)
2012-01-01
The winter of 2011 was exceptionally mild, even in Northern Europe, with unusually warm temperatures. As a result the demand for firewood and solid biomass fuel was low. The European Union's primary energy production from solid biomass contracted by 2.9% slipping to 78.8 Mtoe. The first 4 countries are Germany (11.690 Mtoe), France (9.223 Mtoe), Sweden (8.165 Mtoe) and Finland (7.476 Mtoe) and when the production is relative to the population the first 4 countries become: Finland (1.391 toe/inhab.), Sweden (0.867 toe/inhab.), Latvia (0.784 toe/inhab.) and Estonia (0.644 toe/inhab.). Solid biomass electricity production continued to grow, driven by the additional take-up of biomass co-firing, to reach 72.800 TWh at the end of 2011, it means +2.6% compared to 2010. The energy policy of various states concerning solid biomass is analyzed
DEFF Research Database (Denmark)
2010-01-01
The solid oxide fuel cell comprising a metallic support material, an active anode layer consisting of a good hydrocarbon cracking catalyst, an electrolyte layer, an active cathode layer, and a transition layer consisting of preferably a mixture of LSM and a ferrite to the cathode current collector...
Raouf, M.S.
1963-01-01
The most important literature on theoretical aspects of mixing solids was reviewed.
Only when the mixed materials showed no segregation it was possible to analyse the mixing process quantitatively. In this case the mixture could be described by the 'χ' Square test. Longitudinal mixing could be
Energy Technology Data Exchange (ETDEWEB)
Wilkinson, M. K.; Young, Jr, F. W.
1977-10-01
Research at ORNL into the physical properties of solids is described. Topics covered include: optical, electrical, and magnetic properties of magnesium oxide; ionic conductivity and superconductivity; surface physics and catalysis; defects and impurities in insulating crystals; photovoltaic conversion of solar energy; and fracture studies. (GHT)
Graves, S. R.
2000-01-01
This paper presents viewgraphs on thiokol solid rocket motors. The topics include: 1) Communications; 2) Military and government intelligence; 3) Positioning satellites; 4) Remote sensing; 5) Space burial; 6) Science; 7) Space manufacturing; 8) Advertising; 9) Space rescue space debris management; 10) Space tourism; 11) Space settlements; 12) Hazardous waste disposal; 13) Extraterrestrial resources; 14) Fast package delivery; and 15) Space utilities.
Science Teacher, 1973
1973-01-01
Consists of excerpts from a forthcoming publication of the United States Environmental Protection Agency, Student's Guide to Solid-Waste Management.'' Discusses the sources of wastes from farms, mines, factories, and communities, the job of governments, ways to collect trash, methods of disposal, processing, and suggests possible student action.…
Current Solid Mechanics Research
DEFF Research Database (Denmark)
Tvergaard, Viggo
2016-01-01
About thirty years ago James Lighthill wrote an essay on “What is Mechanics?” With that he also included some examples of the applications of mechanics. While his emphasis was on fluid mechanics, his own research area, he also included examples from research activities in solid mechanics....
Indian Academy of Sciences (India)
-β/β -alumina; solid electrolyte; calcium impurity; specific resistance. 1. Introduction. Since its development in the 1980s, the Na/S battery has been one of the most promising candidates for energy storage applications. The Na/S battery functions based on the elec- trochemical reaction between sodium and sulphur to form.
Indian Academy of Sciences (India)
alumina was synthesized using a solid-state reaction. The changes in ... sive, because of its abundant lowcost raw materials and is suitable for high-volume mass production. The battery is composed of a sodium anode, a sulphur cathode, and. Na. +.
Luminescence and the solid state
Ropp, Richard C
2013-01-01
Since the discovery of the transistor in 1948, the study of the solid state has been burgeoning. Recently, cold fusion and the ceramic superconductor have given cause for excitement. There are two approaches possible to this area of science, namely, that of solid state physics and solid state chemistry, although both overlap extensively. The former is more concerned with electronic states in solids (including electromagnetics) whereas the latter is more concerned with interactions of atoms in solids. The area of solid state physics is well documented, however, there are very few texts which de
SolidWorks Administration Bible
Lombard, Matt
2009-01-01
What you need to prepare, install, and maintain SolidWorks. It's not enough to know how to use SolidWorks, if your job also requires you to install or maintain it, train new users, and implement standards. This in-depth guide was written for those of you who have to actually manage your company's SolidWorks system. From hardware selection to helping users to licensing and more, this is the everyday, bread-and-butter SolidWorks administration resource that IT and CAD managers have been seeking.:; SolidWorks is a powerful 3D solid modeling system that is popular with CAD users everywhere, but of
Solid Phase Characterization of Solids Recovered from Failed Sluicer Arm
Energy Technology Data Exchange (ETDEWEB)
Cooke, Gary A. [Hanford Site (HNF), Richland, WA (United States)
2015-03-09
The Enclosure to this memo discusses the solid phase characterization of a solid sample that was retrieved from the single-shell Tank 241-C-111 extended reach sluicer #2. This sluicer, removed from riser #3 on September 25, 2014, was found to have approximately 0.4 gallons of solid tank waste adhering to the nozzle area.
Solid residues; Os residuos solidos
Energy Technology Data Exchange (ETDEWEB)
NONE
2005-07-01
This chapter gives a general overview on the general effects of the solid waste pollution, the principal pollutants emitted by the oil refineries, control actions for the solid waste emissions, the minimization actions, and the effluent treatment.
Martins, George; Clapp, Leallyn B.
1974-01-01
Discusses the problem of solid waste disposal in the United States, suggests ways in which solid wastes might be reduced, and proposes a number of related topics for student debate in classes or in science clubs. (JR)
Energy Technology Data Exchange (ETDEWEB)
Kamm, James R.; Love, Edward; Robinson, Allen C; Young, Joseph G.; Ridzal, Denis
2013-12-01
We review the edge element formulation for describing the kinematics of hyperelastic solids. This approach is used to frame the problem of remapping the inverse deformation gradient for Arbitrary Lagrangian-Eulerian (ALE) simulations of solid dynamics. For hyperelastic materials, the stress state is completely determined by the deformation gradient, so remapping this quantity effectively updates the stress state of the material. A method, inspired by the constrained transport remap in electromagnetics, is reviewed, according to which the zero-curl constraint on the inverse deformation gradient is implicitly satisfied. Open issues related to the accuracy of this approach are identified. An optimization-based approach is implemented to enforce positivity of the determinant of the deformation gradient. The efficacy of this approach is illustrated with numerical examples.
Lawn, Brian
1993-01-01
This is an advanced text for higher degree materials science students and researchers concerned with the strength of highly brittle covalent-ionic solids, principally ceramics. It is a reconstructed and greatly expanded edition of a book first published in 1975. The book presents a unified continuum, microstructural and atomistic treatment of modern day fracture mechanics from a materials perspective. Particular attention is directed to the basic elements of bonding and microstructure that govern the intrinsic toughness of ceramics. These elements hold the key to the future of ceramics as high-technology materials--to make brittle solids strong, we must first understand what makes them weak. The underlying theme of the book is the fundamental Griffith energy-balance concept of crack propagation. The early chapters develop fracture mechanics from the traditional continuum perspective, with attention to linear and nonlinear crack-tip fields, equilibrium and non-equilibrium crack states. It then describes the at...
DEFF Research Database (Denmark)
2010-01-01
The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...
Cantera, Rodrigo G; Leza, María G; Bachiller, Carmen M
2002-10-01
In this report we describe the preparation and characterization of four polymorphic forms of tenoxicam; they are, three 1:1 stoichiometric solvates with acetonitrile, dioxane, and N,N-dimethylformamide, and an amorphous phase obtained by recrystallization in various solvents. Polymorph IV and solvates with dioxane and N,N-dimethylformamide are reported for the first time in this paper. In addition, three solvates were crystallized in acetone, ethyl acetate, and isopropyl alcohol. These solid forms were characterized by X-ray powder diffraction, differential scanning calorimetry, infrared spectroscopy, thermogravimetry, optical microscopy, and elemental analysis. Solid-state properties, intrinsic dissolution rate, and dissolution kinetics from formulated tablets are also provided. Copyright 2002 Wiley-Liss Inc. and the American Pharmaceutical Association
Beltzer, Abraham I
1988-01-01
Technological developments in composite materials, non-destructive testing, and signal processing as well as biomedical applications, have stimulated wide-ranging engineering investigations of heterogeneous, anisotropic media and surface waves of different types. Wave propagation in solids is now of considerable importance in a variety of applications. The book presents many of the key results in this field and interprets them from a unified engineering viewpoint. The conceptual importance and relevance for applications were the prevailing criteria in selecting the topics. Included are body and surface waves in elastic, viscoelastic, and piezoelectric media and waveguides, with emphasis on the effects of inhomogeneity and anisotropy. The book differs in many aspects from the other monographs dealing with wave propagation in solids. It focuses on physically meaningful theoretical models, a broad spectrum of which is covered, and not on mathematical techniques. Some of the results, particularly those dealing wi...
Flexoelectric Effect in Solids
Zubko, Pavlo; Catalan, Gustau; Tagantsev, Alexander K.
2013-07-01
Flexoelectricity-the coupling between polarization and strain gradients-is a universal effect allowed by symmetry in all materials. Following its discovery several decades ago, studies of flexoelectricity in solids have been scarce due to the seemingly small magnitude of this effect in bulk samples. The development of nanoscale technologies, however, has renewed the interest in flexoelectricity, as the large strain gradients often present at the nanoscale can lead to strong flexoelectric effects. Here we review the fundamentals of the flexoelectric effect in solids, discuss its presence in many nanoscale systems, and look at potential applications of this electromechanical phenomenon. The review also emphasizes the many open questions and unresolved issues in this developing field.
International Nuclear Information System (INIS)
Tiwari, G.P.; Kale, G.B.; Patil, R.V.
1999-01-01
The article presents a brief survey of process of diffusion in solids. It is emphasised that the essence of diffusion is the mass transfer through the atomic jumps. To begin with formal equations for diffusion coefficient are presented. This is followed by discussions on mechanisms of diffusion. Except for solutes which form interstitial solid solution, diffusion in majority of cases is mediated through exchange of sites between an atom and its neighbouring vacancy. Various vacancy parameters such as activation volume, correlation factor, mass effect etc are discussed and their role in establishing the mode of diffusion is delineated. The contribution of dislocations and grain boundaries in diffusion process is brought out. The experimental determination of different types of diffusion coefficients are described. Finally, the pervasive nature of diffusion process in number of commercial processes is outlined to show the importance of diffusion studies in materials science and technology. (author)
International Nuclear Information System (INIS)
Martin, D.H.
1977-01-01
The wide application of scattering experiments in the study of the structures of solids and liquids is surveyed. Part 1 of the review (Martin. Contemp. Phys.;vol. 18, No. 1: Jan. 1977:pp. 81-98) showed how the angular distribution of a scattered beam of photons or neutrons is related by Fourier transform to the space and time-dependent distributions of electrons and nuclei in the scattering target. The use of x-rays and of neutrons in determining time-averaged density distributions was examined. In this part the time-dependent aspects of the distributions for solids and liquids, including helium, are discussed. The dynamical distributions of magnetism (or angular momentum) density are considered, and the present limitations and future possibilities of scattering experiments are examined. (U.K.)
Municipal Solid Waste Resources
Energy Technology Data Exchange (ETDEWEB)
None
2016-06-01
Municipal solid waste (MSW) is a source of biomass material that can be utilized for bioenergy production with minimal additional inputs. MSW resources include mixed commercial and residential garbage such as yard trimmings, paper and paperboard, plastics, rubber, leather, textiles, and food wastes. Waste resources such as landfill gas, mill residues, and waste grease are already being utilized for cost-effective renewable energy generation. MSW for bioenergy also represents an opportunity to divert greater volumes of residential and commercial waste from landfills.
International Nuclear Information System (INIS)
Parazin, R.J.
1995-01-01
This study presents estimates of the solid radioactive waste quantities that will be generated in the Separations, Low-Level Waste Vitrification and High-Level Waste Vitrification facilities, collectively called the Tank Waste Remediation System Treatment Complex, over the life of these facilities. This study then considers previous estimates from other 200 Area generators and compares alternative methods of handling (segregation, packaging, assaying, shipping, etc.)
1979-04-01
SITATEMENT rot tho ahatrai .nti,,ed in IfllorM 0, It diIIIorenl Itroft I.port) 15L %UPPLEMENTARY NOTES 19, KEY WORDS (Continiou on roveaou oido It...yji1 :ppeŽ r prt rni j Lr ,, [VQ I urt, her eL ve.Luprnent into high solids coating systems. The Acryloid AU-568 hns many of the desirable properties
Solid phase extraction membrane
Carlson, Kurt C [Nashville, TN; Langer, Roger L [Hudson, WI
2002-11-05
A wet-laid, porous solid phase extraction sheet material that contains both active particles and binder and that possesses excellent wet strength is described. The binder is present in a relatively small amount while the particles are present in a relatively large amount. The sheet material is sufficiently strong and flexible so as to be pleatable so that, for example, it can be used in a cartridge device.
1996-05-15
15, 324 (1993). 3. L . Wallman , J. Drott, J. Nilsson, and T. Laurell, 8th International Conference on Solid-State Sensors and Actuators and...unlimited. BTIG QUA1ETY IHSESCTBH) l This report is based on studies performed at Lincoln Laboratory, a center for research operated by Massachusetts...analyzer. 34 7-1 Fully depleted transistor results for 50-nm silicon-on-insulator thickness and W/ L = 7/0.25 fjm: (a) n-channel characteristic curves, (b
International Nuclear Information System (INIS)
Medina Bermudez, Clara Ines
1999-01-01
The topic of solid residues is specifically of great interest and concern for the authorities, institutions and community that identify in them a true threat against the human health and the atmosphere in the related with the aesthetic deterioration of the urban centers and of the natural landscape; in the proliferation of vectorial transmitters of illnesses and the effect on the biodiversity. Inside the wide spectrum of topics that they keep relationship with the environmental protection, the inadequate handling of solid residues and residues dangerous squatter an important line in the definition of political and practical environmentally sustainable. The industrial development and the population's growth have originated a continuous increase in the production of solid residues; of equal it forms, their composition day after day is more heterogeneous. The base for the good handling includes the appropriate intervention of the different stages of an integral administration of residues, which include the separation in the source, the gathering, the handling, the use, treatment, final disposition and the institutional organization of the administration. The topic of the dangerous residues generates more expectation. These residues understand from those of pathogen type that are generated in the establishments of health that of hospital attention, until those of combustible, inflammable type, explosive, radio-active, volatile, corrosive, reagent or toxic, associated to numerous industrial processes, common in our countries in development
International Nuclear Information System (INIS)
Ortiz, Paul G.
1995-01-01
The purpose of this document is to study the solid waste issues brought about by a Type C Investigation; ''Disposal of Inappropriate Material in the Los Alamos County Landfill'' (May 28, 1993). The study was completed in August 1995 by Coleman Research Corporation, under subcontract number 405810005-Y for Los Alamos National Laboratory (LANL). The study confirmed the issues identified in the Type C investigation, and also ascertained further issues or problems. During the course of this study two incidents involving hazardous waste resulted in the inappropriate disposal of the waste. An accidental spill, on June 8, 1995, at one of Laboratory buildings was not handled correctly, and ended up in the LAC Landfill. Hazardous waste was disposed of in a solid waste container and sent to the Los Alamos County Landfill. An attempt to locate the hazardous waste at the LAC Landfill was not successful. The second incident involving hazardous waste was discovered by the FSS-8, during a random dumpster surveillance. An interim dumpster program managed by FSS-8 discovered hazardous waste and copper chips in the solid waste, on August 9, 1995. The hazardous waste and copper chips would have been transported to the LAC Landfill if the audit team had not brought the problem to the awareness of the facility waste management personnel
Conformal solids and holography
Esposito, A.; Garcia-Saenz, S.; Nicolis, A.; Penco, R.
2017-12-01
We argue that a SO( d) magnetic monopole in an asymptotically AdS space-time is dual to a d-dimensional strongly coupled system in a solid state. In light of this, it would be remiss of us not to dub such a field configuration solidon. In the presence of mixed boundary conditions, a solidon spontaneously breaks translations (among many other symmetries) and gives rise to Goldstone excitations on the boundary — the phonons of the solid. We derive the quadratic action for the boundary phonons in the probe limit and show that, when the mixed boundary conditions preserve conformal symmetry, the longitudinal and transverse sound speeds are related to each other as expected from effective field theory arguments. We then include backreaction and calculate the free energy of the solidon for a particular choice of mixed boundary conditions, corresponding to a relevant multi-trace deformation of the boundary theory. We find such free energy to be lower than that of thermal AdS. This suggests that our solidon undergoes a solid-to-liquid first order phase transition by melting into a Schwarzschild-AdS black hole as the temperature is raised.
Crangle, John
1991-01-01
Solid state magnetism is important and attempts to understand magnetic properties have led to an increasingly deep insight into the fundamental make up of solids. Both experimental and theoretical research into magnetism continue to be very active, yet there is still much ground to cover before there can be a full understanding. There is a strong interplay between the developments of materials science and of magnetism. Hundreds of new materials have been dis covered, often with previously unobserved and puzzling magnetic prop erties. A large and growing technology exists that is based on the magnetic properties of materials. Very many devices used in everyday life involve magnetism and new applications are being invented all the time. Under standing the fundamental background to the applications is vital to using and developing them. The aim of this book is to provide a simple, up-to-date introduction to the study of solid state magnetism, both intrinsic and technical. It is designed to meet the needs a...
International Nuclear Information System (INIS)
Espinosa G, G.
1994-01-01
The main purpose of this book is to dispose within reach of young professionals in the fields of Physics, Biology, Chemistry, Medicine, Geology, Earth Sciences and Ecology between others, the basis of the Solid State Nuclear Track Methodology (SSNTM). The contents of this book is distributed as follows: Chapter 1, occurs the basic aspects on the formation of tracks in solid state materials. Chapter 2 analyzes the formation of the solid state nuclear tracks in order to three fundamental steps in the process: ionizing radiation, chemical revealed of the track and characterization and reading of the tracks. In the chapter 3, was made an analysis of the possible materials like detecting for tracks, describing the experimental process for the parameters optimization and they are also specified the characteristics of the instrumentation developed for the STD. In the chapter 4, the results obtained in applications are shown specify of the STD, where it was made emphasis in the evaluation of radon within the city and the determination of profiles and pollutants of transuranic radioactive materials. In the chapter 5, it was made an analysis of the applications of the STD as well as their future perspectives in the fields of the science and the technology. Finally, in the conclusions summary the excellent aspects of each one of the chapters and the general results are presented. (Author)