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Jääskeläinen, MarkkuORCID iD iconorcid.org/0000-0002-8049-2425
Alternative names
Publications (10 of 18) Show all publications
Jääskeläinen, M. & Lagerkvist, A. (2017). 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 system. European journal of physics, 38(4), Article ID 045705.
Open this publication in new window or tab >>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 system
2017 (English)In: European journal of physics, ISSN 0143-0807, E-ISSN 1361-6404, Vol. 38, no 4, article id 045705Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
active learning, classroom response system, student learning of magnetic field, student learning of kinematics
National Category
Physical Sciences Educational Sciences
Research subject
No research profile
Identifiers
urn:nbn:se:du-25503 (URN)10.1088/1361-6404/aa73b5 (DOI)000403832500001 ()2-s2.0-85021295799 (Scopus ID)
Available from: 2017-09-08 Created: 2017-09-08 Last updated: 2017-12-20Bibliographically approved
Jääskeläinen, M. (2015). The wave function as matter density: ontological assumptions and experimental consequences. Foundations of physics, 45(6), 591-610
Open this publication in new window or tab >>The wave function as matter density: ontological assumptions and experimental consequences
2015 (English)In: Foundations of physics, ISSN 0015-9018, E-ISSN 1572-9516, Vol. 45, no 6, p. 591-610Article in journal (Refereed) Published
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.

Keywords
Foundations of quantum theory, Wavefunction, Newtonian gravity, Bound states
National Category
Physical Sciences
Research subject
No research profile
Identifiers
urn:nbn:se:du-17487 (URN)10.1007/s10701-015-9884-7 (DOI)000353842200001 ()
Available from: 2015-05-21 Created: 2015-05-21 Last updated: 2017-12-20Bibliographically approved
Jääskeläinen, M. (2012). Gravitational self-localization for spherical masses. Physical Review A. Atomic, Molecular, and Optical Physics, 86(5), Article ID 052105.
Open this publication in new window or tab >>Gravitational self-localization for spherical masses
2012 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 86, no 5, article id 052105Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
American Physical Society, 2012
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:du-11222 (URN)10.1103/PhysRevA.86.052105 (DOI)000310847700002 ()
Available from: 2012-11-08 Created: 2012-11-08 Last updated: 2017-12-07Bibliographically approved
Jääskeläinen, M., Lombard, M. & Zuelicke, U. (2011). Refraction in spacetime. American Journal of Physics, 79(6)
Open this publication in new window or tab >>Refraction in spacetime
2011 (English)In: American Journal of Physics, ISSN 0002-9505, E-ISSN 1943-2909, Vol. 79, no 6Article in journal (Refereed) Published
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.

National Category
Other Physics Topics
Identifiers
urn:nbn:se:du-11200 (URN)10.1119/1.3553459 (DOI)000290585900015 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
Jääskeläinen, M. & Zulicke, U. (2010). Anomalous spin-related quantum phase in mesoscopic hole rings. Physical Review B. Condensed Matter and Materials Physics, 81(15), Article ID 155326.
Open this publication in new window or tab >>Anomalous spin-related quantum phase in mesoscopic hole rings
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 15, article id 155326Article in journal (Refereed) Published
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.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:du-11201 (URN)10.1103/PhysRevB.81.155326 (DOI)000277210500097 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
Bernad, J. Z., Jääskeläinen, M. & Zulicke, U. (2010). Effects of a quantum measurement on the electric conductivity: Application to graphene. Physical Review B. Condensed Matter and Materials Physics, 81(7), Article ID 073403.
Open this publication in new window or tab >>Effects of a quantum measurement on the electric conductivity: Application to graphene
2010 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 7, article id 073403Article in journal (Refereed) Published
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.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:du-11202 (URN)10.1103/PhysRevB.81.073403 (DOI)000274998200020 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
Weatherall, J. O., Search, C. P. & Jääskeläinen, M. (2008). Quantum control of electromagnetically induced transparency dispersion via atomic tunneling in a double-well Bose-Einstein condensate. Physical Review A. Atomic, Molecular, and Optical Physics, 78(1), Article ID 013830.
Open this publication in new window or tab >>Quantum control of electromagnetically induced transparency dispersion via atomic tunneling in a double-well Bose-Einstein condensate
2008 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 78, no 1, article id 013830Article in journal (Refereed) Published
Abstract [en]

Electromagnetically induced transparency (EIT) is an important tool for controlling light propagation and nonlinear wave mixing in atomic gases with potential applications ranging from quantum computing to table top tests of general relativity. Here we consider EIT in an atomic Bose-Einstein condensate (BEC) trapped in a double-well potential. A weak probe laser propagates through one of the wells and interacts with atoms in a three-level Lambda configuration. The well through which the probe propagates is dressed by a strong control laser with Rabi frequency Omega(mu), as in standard EIT systems. Tunneling between the wells at the frequency g provides a coherent coupling between identical electronic states in the two wells, which leads to the formation of interwell dressed states. The macroscopic interwell coherence of the BEC wave function results in the formation of two ultranarrow absorption resonances for the probe field that are inside of the ordinary EIT transparency window. We show that these new resonances can be interpreted in terms of the interwell dressed states and the formation of a type of dark state involving the control laser and the interwell tunneling. To either side of these ultranarrow resonances there is normal dispersion with very large slope controlled by g. We discuss prospects for observing these ultranarrow resonances and the corresponding regions of high dispersion experimentally.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:du-11203 (URN)10.1103/PhysRevA.78.013830 (DOI)000258180300228 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
Zivkovic, M., Jääskeläinen, M., Search, C. P. & Djuric, I. (2008). Sagnac rotational phase shifts in a mesoscopic electron interferometer with spin-orbit interactions. Physical Review B. Condensed Matter and Materials Physics, 77(11), Article ID 115306.
Open this publication in new window or tab >>Sagnac rotational phase shifts in a mesoscopic electron interferometer with spin-orbit interactions
2008 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 77, no 11, article id 115306Article in journal (Refereed) Published
Abstract [en]

The Sagnac effect is an important phase coherent effect in optical and atom interferometers where rotations of the interferometer with respect to an inertial reference frame result in a shift in the interference pattern proportional to the rotation rate. Here, we analyze the Sagnac effect in a mesoscopic semiconductor electron interferometer. We include in our analysis the Rashba spin-orbit interactions in the ring. Our results indicate that spin-orbit interactions increase the rotation-induced phase shift. We discuss the potential experimental observability of the Sagnac phase shift in such mesoscopic systems.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:du-11205 (URN)10.1103/PhysRevB.77.115306 (DOI)000254542800102 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
diva2:565617
Open this publication in new window or tab >>Bifurcations and bistability in cavity-assisted photoassociation of Bose-Einstein-condensed molecules
2007 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 76, no 6, article id 063615Article in journal (Refereed) Published
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.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:du-11206 (URN)10.1103/PhysRevA.76.063615 (DOI)000251985900094 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
Jääskeläinen, M. & Meystre, P. (2006). Coherence dynamics of two-mode condensates in asymmetric potentials. Physical Review A. Atomic, Molecular, and Optical Physics, 73(1), Article ID 013602.
Open this publication in new window or tab >>Coherence dynamics of two-mode condensates in asymmetric potentials
2006 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 73, no 1, article id 013602Article in journal (Refereed) Published
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.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:du-11209 (URN)10.1103/PhysRevA.73.013602 (DOI)000235008900128 ()
Available from: 2012-11-07 Created: 2012-11-07 Last updated: 2017-12-07Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-8049-2425

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