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  • 1. Aarnio, A
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Measurement of the mass and width of the Zo particle from multihadron final states produced in e+e--annihilations1989Ingår i: Physics Letters, nr 231, s. p 539-Artikel i tidskrift (Övrigt vetenskapligt)
  • 2. Aarnio, A
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Study of the hadronic decays of the Zo boson1990Ingår i: Physics Letters, nr 240, s. p 271-Artikel i tidskrift (Övrigt vetenskapligt)
  • 3. Aarnio, A
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Study of the leptonic decays of the Zo boson1990Ingår i: Physics Letters, nr 241, s. p 425-Artikel i tidskrift (Övrigt vetenskapligt)
  • 4. Askebjer, P
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    AMANDA: Status Report from the 1993/94 Campaign and Optical Properties of the South Pole Ice1995Ingår i: Nuclear Physics, nr 38, s. 287-292Artikel i tidskrift (Refereegranskat)
  • 5. Askebjer, P
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    First Data and Future Prospects for AMANDA, the Antarctic Muon and Neutrino Detector1994Ingår i: Antarctic Journal of the United States, nr 29, s. 337-339Artikel i tidskrift (Övrigt vetenskapligt)
  • 6. Askebjer, P
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Remote Surveys of AMANDA1995Ingår i: Contribution to the XXIV International Cosmic Ray Conference, Rome 1995, 1995Konferensbidrag (Övrigt vetenskapligt)
  • 7. Bergström, Lars
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Detection of High Energy Neutrinos in PAN1992Ingår i: Proceedings of the Workshop on High Energy Neutrino Astrophysics, Univ. Hawaai at Manoa, Honolulu, Hawaii, March 23-26, 1992., 1992Konferensbidrag (Övrigt vetenskapligt)
  • 8.
    Bernad, Joszef Zsolt
    et al.
    Massey University.
    Jääskeläinen, Markku
    Högskolan Dalarna. Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Palmerston North, New Zealand.
    Zulicke, Ulrich
    Massey University.
    Effects of a quantum measurement on the electric conductivity: Application to graphene2010Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, nr 7, artikel-id 073403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We generalize the standard linear-response (Kubo) theory to obtain the conductivity of a system that is subject to a quantum measurement of the current. Our approach can be used to specifically elucidate how back-action inherent to quantum measurements affects electronic transport. To illustrate the utility of our general formalism, we calculate the frequency-dependent conductivity of graphene and discuss the effect of measurement-induced decoherence on its value in the dc limit. We are able to resolve an ambiguity related to the parametric dependence of the minimal conductivity.

  • 9. Burns, M
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Physics aspects of the DELPHI vertex detector1988Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 10. Dijkstra, F
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Physics aspects of the DELPHI vertex detector1989Ingår i: Nuclear Instruments and Methods, nr 277, s. p 160-Artikel i tidskrift (Refereegranskat)
  • 11.
    Dutta, Omjyoti
    et al.
    University of Arizona.
    Jääskeläinen, Markku
    Department of Physics and College of Optical Sciences, The University of Arizona, Tucson, Arizona 85721, USA.
    Meystre, Pierre
    University of Arizona.
    Polarizing beam splitter for dipolar molecules2005Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 71, nr 5, artikel-id 051601(R)Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a coherent beam splitter for polarized heteronuclear molecules based on a stimulated Raman adiabatic passage scheme that uses a tripod linkage of electrotranslational molecular states. We show that for strongly polarized molecules the rotational dynamics imposes significantly larger Rabi frequencies than would otherwise be expected, but within this limitation, a full transfer of the molecules to two counterpropagating ground-state wave packets is possible.

  • 12.
    Dutta, Omjyoti
    et al.
    University of Arizona.
    Jääskeläinen, Markku
    Department of Physics and College of Optical Sciences, The University of Arizona.
    Meystre, Pierre
    University of Arizona.
    Single-mode acceleration of matter waves in circular waveguides2006Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 74, nr 2, artikel-id 023609Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ultracold gases in ring geometries hold promise for significant improvements of gyroscopic sensitivity. Recent experiments have realized atomic and molecular storage rings with radii in the centimeter range, sizes whose practical use in inertial sensors requires velocities significantly in excess of typical recoil velocities. We use a combination of analytical and numerical techniques to study the coherent acceleration of matter waves in circular waveguides, with particular emphasis on its impact on single-mode propagation. In the simplest case we find that single-mode propagation is best maintained by the application of time-dependent acceleration force with the temporal profile of a Blackmann pulse. We also assess the impact of classical noise on the acceleration process.

  • 13.
    Dutta, Omjyoti
    et al.
    University of Arizona.
    Jääskeläinen, Markku
    Department of Physics and College of Optical Sciences, The University of Arizona, Tucson, Arizona 85721, USA.
    Meystre, Pierre
    University of Arizona.
    Thomas-Fermi ground state of dipolar fermions in a circular storage ring2006Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 73, nr 4, artikel-id 043610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent developments in the field of ultracold gases has led to the production of degenerate samples of polar molecules. These have large static electric-dipole moments, which in turn causes the molecules to interact strongly. We investigate the interaction of polar particles in waveguide geometries subject to an applied polarizing field. For circular waveguides, tilting the direction of the polarizing field creates a periodic inhomogeneity of the interparticle interaction. We explore the consequences of geometry and interaction for stability of the ground state within the Thomas-Fermi model. Certain combinations of tilt angles and interaction strengths are found to preclude the existence of a stable Thomas-Fermi ground state. The system is shown to exhibit different behavior for quasi-one-dimensional and three-dimensional trapping geometries.

  • 14. Erlandsson, Bengt
    et al.
    Johansson, Sverker
    Högskolan Dalarna, Ej akademianställd. Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Measurements of the Absorption Length of the Ice at the South Pole in the Wavelength Interval 410 nm to 610 nm1995Ingår i: The XXIV International Cosmic Ray Conference, Rome 1995, 1995Konferensbidrag (Övrigt vetenskapligt)
  • 15.
    Fritsch, Katarina
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Pedagogiskt arbete.
    Meningsskapande samtal om fysikens begrepp: Att utgå från elevernas erfarenheter och förförståelse2017Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Syftet med studien är att undersöka vad tidigare forskning säger om hur lärare kan organisera fysikundervisningen för att stödja elever, i årskurs 4 – 9, till meningsskapande samtal om fysikens begrepp. I denna systematiska litteraturstudie presenteras resultat utifrån litteratur som noggrant valts ut genom en systematisk sökningsprocess i databaserna Summon, ERIC, Nordina och avhandlingar.se där all litteratur har genomgått peer review. Studiens resultat visar att elever tillsammans bidrar till meningsskapande samtal genom att tillföra egna erfarenheter och förkunskaper om fysikens begrepp. Studien visar hur eleverna kan diskutera fritt så länge de har något att diskutera utifrån, exempelvis praktiska experiment, bilder, artefakter eller texter. Lärarens roll är sedan att stödja eleverna till att använda och förstå de korrekta vetenskapliga begreppen. Studien visar att läraren kan göra detta genom att koppla till vardagliga objekt och företeelser, ställa utmanande frågor, synliggöra nyckelbegrepp och elevers förförståelse samt återkoppla till elevers lärande. Med dessa olika metoder agerar läraren som en riktningsgivare som guidar eleven i en kunskapsutvecklande riktning. Genom att utgå från samt synliggöra elevernas förförståelse får både elever och lärare kunskap om eventuella missuppfattningar. Detta bidrar i sin tur till meningsskapande samtal då eleverna börjar ifrågasätta samt förändra och utveckla sin förståelse för fysiken begrepp. 

  • 16. Gray, P
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    The Design of a Neutrino Telescope Using Natural Deep Ice as a Particle Detector1995Ingår i: The XXIV International Cosmic Ray Conference, Rome 1995, 1995Konferensbidrag (Övrigt vetenskapligt)
  • 17. Halzen, Francis
    et al.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Status of the AMANDA South Pole Neutrino Detector1996Ingår i: The International Workshop on Aspects of Dark Matter in Astrophysics and Particle Physics, Heidelberg, Germany, September 1996, 1996Konferensbidrag (Övrigt vetenskapligt)
  • 18.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    A study of mu-mu- and e-mu-pairs produced in 450 GeV/c p-Be--collisions in HELIOS, and software development for DELPHI.1990Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The main part of this thesis treats measurements in the HELIOS experiment of the production of e-mu and mu+mu-pairs in 450 GeV/c p-Be collisions. The mumu measurement covers the kinematical covers the kinematical range of 2Mmu < M < 1.5 GeV, 0.03 < xF < 0.25, and 0 < pT < 2 GeV. Production of the vector mesons rho, omega , and phi is observed. The branching ratio omega to mu+mu- is for the first time experimentally measured. The continuum at masses below the mu mass is studied, and compared with the contributions from known sources, normalized to the vector meson peaks in the mu+mu- mass spectrum, and to measurements in this experiment of the mu cross section. The res ult is compared with that of other experiments, discussed in terms of different background estimates used. A significant signal of unlike-sign e-mu-pairs is observed, forming a continuum peaking at a mass below 500 MeV. Correlations between e-mu and neutrino production are studied. The shape of the e-mu mass and missng-energy spectra indicate significant non-charm contributions. A search for lepton-number-violating decays is made, resulting in upper limits on a number of branching ratios. Also discussed here is the author's work in the DELPHI experiment, contributions that are related to analysis of heavy quark production. Keywords: muon. pair, dimuon, dilepton, lepton, low mass, continuum, eta, rho, omega, branching ratio, emu, e-mu, mue, mu-e, muon-electron, electron-muon, electron, charm, neutrino, missing energy

  • 19.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Cosmic rays and free neutrinos affect decay rates2005Ingår i: The Counter-Creationism handbook, Westport: Greenwood Publishing , 2005Kapitel i bok, del av antologi (Övrig (populärvetenskap, debatt, mm))
  • 20.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Dimuon production in 450 GeV/c p-Be collisions1990Ingår i: Proceedings of the Pittsburgh Workshop on Soft Lepton Pair and Photon Production, Sept 6-8, 1990, 1990Konferensbidrag (Övrigt vetenskapligt)
  • 21.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, Medie-, litteratur- och språkdidaktik.
    Från ostkupan till den stora smällen2004Bok (Övrigt vetenskapligt)
  • 22.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Measuring the energy of multi-TeV muons with a water Cherenkov detector1991Ingår i: Proceedings of the 22nd International Cosmic Ray Conference, Dublin, Aug 11-23, 1991, 1991Konferensbidrag (Refereegranskat)
  • 23.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Sagan om hur allting började1996Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 24.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    The Cathedral of Physics1997Ingår i: Vetenskapens ansikten / [ed] Hans-Albin Larsson, Jönköping: Jönköping University Press , 1997Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 25.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    The Solar FAQ: Solar Neutrinos and Other Solar Oddities1998Övrigt (Övrig (populärvetenskap, debatt, mm))
  • 26.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    The Solar Neutrino Problem is Not a Solar Problem1999Rapport (Övrig (populärvetenskap, debatt, mm))
  • 27.
    Johansson, Sverker
    Högskolan i Jönköping.
    The transverse energy distribution in 16O-nucleus collisions at 60 and 200 GeV per nucleon1988Ingår i: Zeitschrift für Physik C, Vol. 38, s. 383-395Artikel i tidskrift (Refereegranskat)
  • 28.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Transverse energy distribution in 16O -nucleus collisions1987Ingår i: 6th International conference on ultra-relativistic nucleus-nucleus collisions: Nordkirchen, FR Germany, 24 - 28 Aug 1987, 1987, s. 15-18Konferensbidrag (Övrigt vetenskapligt)
  • 29.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Transverse energy distribution in 16O -nucleus collisions1988Ingår i: Zeitschrift für Physik C, nr 38, s. 15-18Artikel i tidskrift (Övrigt vetenskapligt)
  • 30.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Universums mörka hemlighet1993Ingår i: Högskriften: (personaltidning för Högskolan i Jönköping), Vol. april/majArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 31.
    Johansson, Sverker
    Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Vackrare värld med fysik2006Ingår i: Lärandets konst: betraktelser av estetiska dimensioner i lärandet, Lund: Studentlitteratur , 2006, s. 105-126Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 32.
    Junkala, Hannele
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Naturvetenskap.
    Fysik, formler, förkroppsligande och förståelse2016Ingår i: Forskning i Naturvetenskapernas Didaktik: Konferenstema: Kroppsligt lärande i den naturvetenskapliga undervisningen, 2016Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Vad kan barn och elever vinna i förståelse genom att uppleva olika begrepp med kroppen och sinnena? Vi utför några försök inom naturvetenskap och teknik och diskuterar hur kroppsliga upplevelser kan leda till ökad förståelse av bland annat tyngdpunkt, balans, krafter, enkla maskiner och temperatur. Genom att jämföra några laborativa moment, som utförs med material som man ofta hittar i traditionella NO-salar, med försök där man medvetet använder kroppen och sinnena, får vi gemensamma upplevelser att diskutera vidare kring. Vilka fler fenomen och begrepp behöver vi hitta och utveckla försök till, som kan bidra till att fördjupa elevernas förståelse?  Vi delar med oss av våra erfarenheter och frågor, tolkningar av styrdokument samt vad vi eventuellt känner till från aktuell forskning.

  • 33.
    Junkala, Hannele
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle, Naturvetenskap.
    Lekplatsfysik som ett moment i utomhuspedagogik för Erasmusstudenter2016Konferensbidrag (Refereegranskat)
    Abstract [sv]

    Lekplatsfysik som ett moment i utomhuspedagogik för Erasmusstudenter

    Sedan vårterminen 2013 ger Högskolan Dalarna kursen Outdoor Education för internationella studenter inom Erasmusprogrammet. Efter kursen ska studenterna bland annat visa kunskap om hur utomhusdidaktik kan användas i naturvetenskapsundervisningen samt reflektera över utomhusdidaktik i ett jämförande internationellt perspektiv. De flesta av studenterna läser till lärare men några studerar till ingenjör, kurator eller jurist.

    Undervisningen i lekplatsfysik äger rum på en lekplats mellan Lugnets camping och riksskidstadion i Falun, belägen nära Högskolan Dalarna. I försöken ingår moment med eld, balans, gravitation, fritt fall, gungor, karuseller, burktelefoner och ballonger. Aktiviteterna pågår under en halv dag och följs upp med en hemuppgift som består av några ytterligare experiment kopplade till gungbräda, balans, rullande burkar, pendel samt teori. Avslutningsvis följer frågor om vad läroplanen i hemlandet anger om fysikundervisning och hur studenterna anser att de kan använda lekplatsfysik i sina framtida yrken samt om de kan hitta användbara hemsidor på nätet på deras eget språk. En del av svaren visar att studenterna uppfattar fysik som svårt från sin egen skolgång på grund av tonvikt på teori. De ser efter kursen möjlighet att väcka intresse för ämnet hos elever i framtiden genom upplevelser av fysik med kroppens sinnen utanför det traditionella klassrummet.

  • 34.
    Jääskeläinen, Markku
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik.
    Gravitational self-localization for spherical masses2012Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 86, nr 5, artikel-id 052105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, I consider the center-of-mass wave function for a homogenous sphere under the influence of the self-interaction due to Newtonian gravity. I solve for the ground state numerically and calculate the average radius as a measure of its size. For small masses, M≲10−17 kg, the radial size is independent of density, and the ground state extends beyond the extent of the sphere. For masses larger than this, the ground state is contained within the sphere and to a good approximation given by the solution for an effective radial harmonic-oscillator potential. This work thus determines the limits of applicability of the point-mass Newton Schrödinger equations for spherical masses. In addition, I calculate the fringe visibility for matter-wave interferometry and find that in the low-mass case, interferometry can in principle be performed, whereas for the latter case, it becomes impossible. Based on this, I discuss this transition as a possible boundary for the quantum-classical crossover, independent of the usually evoked environmental decoherence. The two regimes meet at sphere sizes R≈10−7 m, and the density of the material causes only minor variations in this value.

  • 35.
    Jääskeläinen, Markku
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik.
    The wave function as matter density: ontological assumptions and experimental consequences2015Ingår i: Foundations of physics, ISSN 0015-9018, E-ISSN 1572-9516, Vol. 45, nr 6, s. 591-610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wavefunction is the central mathematical entity of quantum mechanics, but it still lacks a universally accepted interpretation. Much effort is spent on attempts to probe its fundamental nature. Here I investigate the consequences of a matter ontology applied to spherical masses of constant bulk density. The governing equation for the center-of-mass wavefunction is derived and solved numerically. The ground state wavefunctions and resulting matter densities are investigated. A lowering of the density from its bulk value is found for low masses due to increased spatial spreading. A discussion of the possibility to experimentally observe these effects is given and the possible consequences for choosing an ontological interpretation for quantum mechanics are commented upon.

  • 36.
    Jääskeläinen, Markku
    et al.
    Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on the Hudson, Hoboken, New Jersey 07030, USA.
    Corvino, Frank
    Search, Christopher P.
    Fessatidis, Vassilios
    Quantum pumping of electrons by a moving modulated potential2008Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, nr 15, s. 155319-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantum pumping holds great potential for future applications in microtechnology and nanotechnology. Its main feature, which is the dissipationless charge transport, is theoretically possible via several different mechanisms. However, since no unambiguous verification has been experimentally demonstrated, the question of finding a viable mechanism for pumping remains open. Here, we study quantum pumping in an one dimensional electron waveguide with a single time-dependent barrier. The quantum pumping of electrons by using a potential barrier whose height and position are harmonically varied is analytically analyzed and by numerically solving the time-dependent Schrodinger equation. The pumped charge is analytically modeled by including two contributions in linear response theory. First, the scattering of electrons off a potential moving slowly through matter waves gives a contribution independent of the translational velocity of the potential. Second, Doppler-shifted scattering events give rise to a velocity dependent contribution, which is found in general to be small in comparison with the first one. The relative phase between the oscillations of the height and position is found to be the factor that determines to what extent either contribution is present.

  • 37.
    Jääskeläinen, Markku
    et al.
    Department of Physics and Engineering Physics, Stevens Institute of Technology, Castle Point on the Hudson, Hoboken, New Jersey 07030, USA.
    Jeong, Jaeyoon
    Stevens Institute of Technology.
    Search, Christopher P.
    Stevens Institute of Technology.
    Bifurcations and bistability in cavity-assisted photoassociation of Bose-Einstein-condensed molecules2007Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 76, nr 6, artikel-id 063615Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the photoassociation of Bose-Einstein condensed atoms into molecules using an optical cavity field. The driven cavity field introduces a dynamical degree of freedom into the photoassociation process, whose role in determining the stationary behavior has not previously been considered. The semiclassical stationary solutions for the atom and molecules as well as the intracavity field are found and their stability and scaling properties are determined in terms of experimentally controllable parameters including driving amplitude of the cavity and the nonlinear interactions between atoms and molecules. For weak cavity driving, we find a bifurcation in the atom and molecule number occurs that signals a transition from a stable steady state to nonlinear Rabi oscillations. For a strongly driven cavity, there exists bistability in the atom and molecule number.

  • 38.
    Jääskeläinen, Markku
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik.
    Lagerkvist, Andreas
    Högskolan Dalarna, Akademin Industri och samhälle, Matematik/tillämpad matematik.
    Why do they not answer and do they really learn?: A case study in analysing student response flows in introductory physics using an audience response system2017Ingår i: European journal of physics, ISSN 0143-0807, E-ISSN 1361-6404, Vol. 38, nr 4, artikel-id 045705Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we investigate teaching with a classroom response system in introductory physics with emphasis on two issues. First, we discuss retention between question rounds and the reasons why students avoid answering the question a second time. A question with declining response rate was followed by a question addressing the student reasons for not answering. We find that there appear to be several reasons for the observed decline, and that the students need to be reminded. We argue that small drops are unimportant as the process appears to work despite the drops. Second, we discuss the dynamics of learning in a concept-sequence in electromagnetism, where a majority of the students, despite poor statistics in a first round, manage to answer a followup question correctly. In addition, we analyse the response times for both situations to connect with research on student reasoning on situations with misconception-like answers. From the combination of the answer flows and response time behaviours we find it plausible that conceptual learning occurred during the discussion phase.

  • 39.
    Jääskeläinen, Markku
    et al.
    Institute of Fundamental Sciences and MacDarmid Institute for Advanced Materials and Nanotechnology, Massey University, Manawatu Campus, Palmerston North, New Zealand.
    Lombard, Marijke
    Massey University.
    Zuelicke, Ulrich
    Massey University.
    Refraction in spacetime2011Ingår i: American Journal of Physics, ISSN 0002-9505, E-ISSN 1943-2909, Vol. 79, nr 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Refraction, interference, and diffraction are distinguishing features of wavelike phenomena. Although they are usually associated only with a purely spatial wave-propagation pattern, analogs to interference and diffraction involving the spatio-temporal dynamics of waves in one dimension have been discussed. We complete the triplet of analogies by discussing how spatio-temporal analogs to refraction are exhibited by a quantum particle in one dimension that is scattering off a step barrier. Similarly, birefringence in spacetime occurs for a spin-1/2 particle in a magnetic field.

  • 40.
    Jääskeläinen, Markku
    et al.
    Department of Physics and College of Optical Sciences, The University of Arizona, Tucson, Arizona 85721, USA.
    Meystre, Pierre
    University of Arizona.
    Coherence dynamics of two-mode condensates in asymmetric potentials2006Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 73, nr 1, artikel-id 013602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Detection of weak forces with an accuracy beyond the standard quantum limit holds promise both for fundamental research and for technological applications. Schemes involving ultracold atoms for such measurements are now considered to be prime candidates for increased sensitivity. In this paper we use a combination of analytical and numerical techniques to investigate the possible subshot-noise estimation of applied force fields through detection of coherence dynamics of Bose-condensed atoms in asymmetric double-well traps. Following a semiclassical description of the system dynamics and fringe visibility, we present numerical simulations of the full quantum dynamics that demonstrate the dynamical production of phase squeezing beyond the standard quantum limit. Nonlinear interactions are found to limit the achievable amount to a finite value determined by the external weak force.

  • 41.
    Jääskeläinen, Markku
    et al.
    Department of Physics and College of Optical Sciences, The University of Arizona, Tucson, Arizona 85721, USA.
    Meystre, Pierre
    University of Arizona.
    Dynamics of Bose-Einstein condensates in double-well potentials2005Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 71, nr 4, artikel-id 043603Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the dynamics of Bose-Einstein condensates in symmetric double-well potentials following a sudden change of the potential from the Mott-insulator to the superfluid regime. We introduce a continuum approximation that maps that problem onto the wave-packet dynamics of a particle in an anharmonic effective potential. For repulsive two-body interactions the visibility of interference fringes that result from the superposition of the two condensates following a stage of ballistic expansion exhibits a collapse of coherent oscillations onto a background value whose magnitude depends on the amount of squeezing of the initial state. Strong attractive interactions are found to stabilize the relative number dynamics. We visualize the dynamics of the system in phase space using a quasiprobability distribution that allows for an intuitive interpretation of the various types of dynamics.

  • 42.
    Jääskeläinen, Markku
    et al.
    Laser Physics and Quantum Optics, Royal Institute of Technology, Roslagstullsbacken 21 SE-10691 Stockholm, Sweden.
    Stenholm, Stig
    echnology, Roslagstullsbacken 21 SE-10691 Stockholm, Sweden.
    Adiabatic propagation in potential structures2002Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 66, nr 2, artikel-id 023608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work the adiabatic approximation is applied to the propagation of matter waves in confined geometries like those experimentally realized in recent atom optical experiments. Adiabatic propagation along a channel is assumed not to mix the various transverse modes. Nonadiabatic corrections arise from the potential squeezing and bending. Here we investigate the effect of the former. Detailed calculations of two-dimensional propagation are carried out both exactly and in an adiabatic approximation. This offers the possibility to analyze the validity of adiabaticity criteria. A semiclassical (sc) approach, based on the sc Massey parameter is shown to be inadequate, and the diffraction due to wave effects must be included separately. This brings in the Fresnel parameter well known from optical systems. Using these two parameters, we have an adequate understanding of adiabaticity on the system analyzed. Thus quantum adiabaticity must also take cognizance of the intrinsic diffraction of matter waves.

  • 43.
    Jääskeläinen, Markku
    et al.
    Kungliga tekniska högskolan.
    Stenholm, Stig
    Kungliga tekniska högskolan.
    Localization in splitting of matter waves2003Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 68, nr 3, artikel-id 033607Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we present an analysis of how matter waves, guided as propagating modes in potential structures, are split under adiabatic conditions. The description is formulated in terms of localized states obtained through a unitary transformation acting on the mode functions. The mathematical framework results in coupled propagation equations that are decoupled in the asymptotic regions as well before as after the split. The resulting states have the advantage of describing propagation in situations, for instance matter-wave interferometers, where local perturbations make the transverse modes of the guiding potential unsuitable as a basis. The different regimes of validity of adiabatic propagation schemes based on localized versus delocalized basis states are also outlined. Nontrivial dynamics for superposition states propagating through split potential structures is investigated through numerical simulations. For superposition states the influence of longitudinal wave-packet extension on the localization is investigated and shown to be accurately described in quantitative terms using the adiabatic formulations presented here.

  • 44.
    Jääskeläinen, Markku
    et al.
    Laser Physics and Quantum Optics, Royal Institute of Technology, Roslagstullsbacken 21 SE-10691 Stockholm, Sweden.
    Stenholm, Stig
    Quantum-state measurement through ballistic expansion of matter waves2002Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 66, nr 4, s. 043612-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a method for state measurement in atomic waveguides is presented. Matter waves exiting a terminated waveguide are allowed to expand ballistically. Measurement is performed by spatially resolved detection of laser-induced fluorescence. We describe in detail the motion of wave packets both in the guiding potential and in the region of free expansion. It is shown that different modes can be distinguished in a straightforward manner and that the same is true for coherent superpositions after introduction of a controlled phase shift. The sensitivity of the transition from adiabatic guiding to free expansion is investigated in detail. It is found that adiabatic readjustment, which will distort the original state, can be considerable but may be avoided by proper choice of potential parameters. The method proposed here is shown to be feasible for experiments in atom optics through utilizing numerical estimates.

  • 45. Jääskeläinen, Markku
    et al.
    Stenholm, Stig
    Laser Physics and Quantum Optics, Royal Institute of Technology, Roslagstullsbacken 21, SE-10691 Stockholm, Sweden.
    Reflection of matter waves in potential structures2002Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 66, nr 5, s. 053605-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper the behavior of matter waves in suddenly terminated potential structures is investigated numerically. It is shown that there is no difference between a fully quantum mechanical treatment and a semiclassical one with regards to energy redistribution. For the quantum case it is demonstrated that there can be substantial reflection at the termination. The neglect of backscattering by the semiclassical method brings about major differences in the case of low kinetic energies. A simple phenomenological model is shown to partially explain the observed backscattering using dynamics of reduced dimensionality.

  • 46.
    Jääskeläinen, Markku
    et al.
    Optical Sciences Center, The University of Arizona, Tucson, Arizona 85721, USA.
    Zhang, Weiping
    Department of Physics, Tsinghua University, Beijing 100084, China.
    Meystre, Pierre
    Optical Sciences Center, The University of Arizona, Tucson, Arizona 85721, USA.
    Limits to phase resolution in matter-wave interferometry2004Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 70, nr 6, artikel-id 063612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the quantum dynamics of a two-mode Bose-Einstein condensate in a time-dependent symmetric double-well potential using analytical and numerical methods. The effects of internal degrees of freedom on the visibility of interference fringes during a stage of ballistic expansion are investigated varying particle number, nonlinear interaction sign and strength, as well as tunneling coupling. Expressions for the phase resolution are derived and the possible enhancement due to squeezing is discussed. In particular, the role of the superfluid-Mott insulator crossover and its analog for attractive interactions is recognized.

  • 47.
    Jääskeläinen, Markku
    et al.
    Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Manawatu Campus, Private Bag 11 222, Palmerston North 4442, New Zealand.
    Zulicke, Ulrich
    Massey University.
    Anomalous spin-related quantum phase in mesoscopic hole rings2010Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, nr 15, artikel-id 155326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have obtained numerically exact results for the spin-related geometric quantum phases that arise in p-type semiconductor ring structures. The interplay between gate-controllable (Rashba) spin splitting and quantum-confinement-induced mixing between hole-spin states causes a much higher sensitivity of magnetoconductance oscillations to external parameters than previously expected. Our results imply a much-enhanced functionality of hole-ring spin-interference devices and shed new light on recent experimental findings.

  • 48.
    Linnaeus, Staffan
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik.
    Phase-integral solution of the radial Dirac equation2010Ingår i: Journal of Mathematical Physics, ISSN 0022-2488, E-ISSN 1089-7658, Vol. 51, nr 3, artikel-id 032304Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A phase-integral (WKB) solution of the radial Dirac equation is constructed, retaining perfect symmetry between the two components of the wave function and introducing no singularities except at the classical transition points. The potential is allowed to be the time component of a four-vector, a Lorentz scalar, a pseudoscalar, or any combination of these. The key point in the construction is the transformation from two coupled first-order equations constituting the radial Dirac equation to a single second-order Schroumldinger-type equation. This transformation can be carried out in infinitely many ways, giving rise to different second-order equations but with the same spectrum. A unique transformation is found that produces a particularly simple second-order equation and correspondingly simple and well-behaved phase-integral solutions. The resulting phase-integral formulas are applied to unbound and bound states of the Coulomb potential. For bound states, the exact energy levels are reproduced.

  • 49.
    Linnaeus, Staffan
    Högskolan Dalarna, Akademin Industri och samhälle, Fysik.
    Stokes constants for a singular wave equation2005Ingår i: Journal of Mathematical Physics, ISSN 0022-2488, E-ISSN 1089-7658, Vol. 45, nr 5, artikel-id 053505Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Stokes constants for arbitrary-order phase-integral approximations are calculated when the square of the wave number has either two simple zeros close to a second-order pole or one simple zero close to a first-order pole. The treatment is based on uniform approximations. All parameters may assume general complex values.

  • 50. Miller, Tim
    et al.
    Johansson, Sverker
    Högskolan Dalarna, Ej akademianställd. Högskolan för lärande och kommunikation, Högskolan i Jönköping, HLK, Ämnesforskning.
    Initial Analysis of Coincident Events Between the SPASE and AMANDA Detectors1995Ingår i: Nuclear Physics, nr 43, s. 245-248Artikel i tidskrift (Refereegranskat)
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