Butsuri
Online ISSN : 2423-8872
Print ISSN : 0029-0181
ISSN-L : 0029-0181
Volume 72 , Issue 6
Showing 1-19 articles out of 19 articles from the selected issue
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  • Atsushi Nishizawa
    Type: Researches
    2017 Volume 72 Issue 6 Pages 398-401
    Published: June 05, 2017
    Released: June 05, 2018
    JOURNALS FREE ACCESS

    Detections of gravitational wave (GW) from binary black holes, GW150914 and GW151226, suggest that the properties of the GW are consistent with general relativity. After the first detection, the origin of binary black holes has been discussed actively among researchers. However, there are still many possibilities for the formation scenario of binary black holes: the isolated binary model, the star cluster model, primordial black holes, and etc. In this article we discuss how we can discriminate the formation scenarios with current and future GW observations, particularly focusing on our recent proposals using orbital eccentricities and spatial clustering of binary black holes.

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  • Tomohiro Yokoyama
    Type: Researches
    2017 Volume 72 Issue 6 Pages 402-407
    Published: June 05, 2017
    Released: June 05, 2018
    JOURNALS FREE ACCESS

    We theoretically investigate a multi-terminal Josephson junction. Such junctions can be realized, for instance, with crossed InSb nanowires. N superconductors can define N-1 independent superconducting phase differences. The spectrum of Andreev bound states is 2π periodic in all the phase differences. By regarding the phase differences as quasimomenta, the Andreev spectrum in the multi-terminal junction can be proposed as an energy band of artificial material. We exhibit topological Weyl singularity in the Andreev spectrum. The Weyl singularity requires more than three superconducting terminals. The Weyl points are found in a 3D space of the phase differences. They come always in groups of four. The singularity is present even in the absence of SO interaction, thus even for doubly degenerate spectrum. The SO interaction splits energetically the conical spectrum of the Weyl points, however their topological property does not disappear. Since the Weyl points host positive or negative topological charges, they are removed only a pair annihilation when they meet. The topological charge works as monopole of Berry curvature field. To detect such topological property, we discuss quantized transconductance due to the Chern number when one applies finite voltages to the superconducting terminals.

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  • Naomichi Hatano
    Type: Researches
    2017 Volume 72 Issue 6 Pages 408-414
    Published: June 05, 2017
    Released: June 05, 2018
    JOURNALS FREE ACCESS

    The arrow of time is a big and long-standing problem of physics. It refers to a situation in which one phenomenon is more often observed than its time-reversal counterpart as time goes by. We pinpoint the instance at which the arrow of time appears in microscopic quantum mechanics. We first show that the Schrödinger equation, despite that it is time-reversal symmetric, can harbor eigenstates that break time-reversal symmetry. The eigenstates always appear as a pair of those which are time reversal to each other, namely decaying and growing eigenstates. We next show that the decaying eigenstates excel in the initial-state problem for t>0, whereas the growing ones dominate in the terminal-state problem for t<0. This explains why a two-state atom in a radiation field always decays as in the theory of the Einstein coefficients.

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  • Masaki Matsuda, Noriaki Hanasaki
    Type: Researches
    2017 Volume 72 Issue 6 Pages 415-421
    Published: June 05, 2017
    Released: June 05, 2018
    JOURNALS FREE ACCESS

    Metallophthalocyanine (M(Pc)) derivatives are ideal components to bring out the giant magnetoresistance (GMR) effect in molecular compounds. In the M (Pc) molecule, both the conducting π electron and the local d moment exist, and the strong intramolecular π–d interaction, which corresponds to the Hund's coupling in the manganese oxides, plays an important role in the molecular GMR effect. By the molecular design on the central transition metal ion and the π conjugating ligand, we investigated the dependence of the GMR effect on the local-moment density, and tuned the intrinsic π–d interaction.

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