Updated on 2024/03/18

写真a

 
NAMBU, Yasusada
 
Organization
Graduate School of Science Associate professor
Graduate School
Graduate School of Science
Undergraduate School
School of Science
Title
Associate professor
Contact information
メールアドレス

Degree 1

  1. 理学博士 （ 1989.5   広島大学 ） 

To the head of Degree.▲

Research Interests 5

  1. general relativity

  2. 量子情報

  3. ブラックホール磁気圏

  4. 重力の量子性

  5. ブラックホール

To the head of Research Interests.▲

Research Areas 2

  1. Others / Others  / 量子情報

  2. Others / Others  / Elementary Particle/Atomic Nucleus/Cosmic Ray/Space Physics

To the head of Research Areas.▲

Current Research Project and SDGs 3

  1. 重力の量子性

  2. ブラックホール時空での波動光学

  3. 非一様宇宙と量子論

To the head of Current Research Project and SDGs.▲

Education 1

  1. Hiroshima University

    　 More details

    Country： Japan

To the head of Education.▲

Professional Memberships 2

  1. 日本物理学会

  2. IAU

To the head of Professional Memberships.▲
 

Papers 38

  1. Entanglement partners and monogamy in de Sitter universes

    Nambu, Y; Yamaguchi, K

    PHYSICAL REVIEW D   Vol. 108 ( 4 )   2023.8

    　More details

    Publisher：Physical Review D  

    We investigate entanglement of local spatial modes defined by a quantum field in a de Sitter universe. The introduced modes show disentanglement behavior when the separation between two regions where local modes are assigned becomes larger than the cosmological horizon. To understand the emergence of separability between these local modes, we apply the monogamy inequality proposed by S. Camalet. We embed the focusing bipartite mode defined by the quantum field in a pure four-mode Gaussian state, and identify its partner modes. Then applying a Gaussian version of the monogamy relation, we show that the external entanglement between the bipartite mode and its partner modes constrains the entanglement of the bipartite mode. Thus the emergence of separability of local modes in the de Sitter universe can be understood from the perspective of entanglement monogamy.

    DOI： 10.1103/PhysRevD.108.045002

    Web of Science

    Scopus

  2. Particle creation and entanglement in a dispersive model with step velocity profile

    Osawa, Y; Nambu, Y

    PHYSICAL REVIEW D   Vol. 107 ( 10 )   2023.5

    　More details

    Publisher：Physical Review D  

    We investigate particle creation and entanglement structure in a dispersive model with subluminal dispersion relation. Assuming the step function spatial velocity profile of the background flow, mode functions for a massless scalar field are exactly obtained by the matching method. Power spectrums of created particles are calculated for the subsonic and the trans-sonic flow cases. For the trans-sonic case, the sonic horizon exists, and created particles show the Planckian distribution for the low frequency region, but the thermal property disappears for the high frequency region near the cutoff frequency introduced by the nonlinear dispersion. For the subsonic case, although the sonic horizon does not exist, the effective group velocity horizon appears due to the nonlinear dispersion for the high frequency region, and an approximate thermal property of the power spectrum arises. The relation between particle creation and entanglement between each mode is also discussed.

    DOI： 10.1103/PhysRevD.107.105005

    Web of Science

    Scopus

  3. Quantumness of gravity in harmonically trapped particles

    Kaku Youka, Maeda Shin' ya, Nambu Yasusada, Osawa Yuki

    PHYSICAL REVIEW D   Vol. 106 ( 12 )   2022.12

    　More details

    Publisher：Physical Review D  

    This study investigates the quantumness of gravity under the setup of the atomic interferometry from the viewpoint of mass-energy equivalence. We evaluated interference visibility considering a particle with internal energy levels in a harmonic trapping potential. As per the result, for a spatially superposed gravitational source mass, interference visibility exhibits collapse and revival behavior, which implies that an initial separable internal state evolves to the entangled state with respect to the degrees of freedom of the center of mass, the internal energy levels, and the external source state. In particular, it does not exhibit revival behavior when gravity is treated as a quantum interaction, while it revives with a finite period for a semiclassical treatment of gravity. We also examined the temporal behavior of entanglement negativity and found that the nonrevival behavior of visibility reflects the creation of the entanglement between the internal energy state and the external source state which is uniquely induced by the quantum interaction of gravity in accordance with the weak equivalence principle.

    DOI： 10.1103/PhysRevD.106.126005

    Web of Science

    Scopus

  4. Entanglement Renyi Entropy of Two Disjoint Intervals for Large c Liouville Field Theory

    Tsujimura Jun, Nambu Yasusada

    ENTROPY   Vol. 24 ( 12 )   2022.12

    　More details

    Publisher：Entropy  

    Entanglement entropy (EE) is a quantitative measure of the effective degrees of freedom and the correlation between the sub-systems of a physical system. Using the replica trick, we can obtain the EE by evaluating the entanglement Renyi entropy (ERE). The ERE is a q-analogue of the EE and expressed by the q replicated partition function. In the semi-classical approximation, it is apparently easy to calculate the EE because the classical action represents the partition function by the saddle point approximation and we do not need to perform the path integral for the evaluation of the partition function. In previous studies, it has been assumed that only the minimal-valued saddle point contributes to the EE. In this paper, we propose that all the saddle points contribute comparably but not necessarily equally to the EE by dealing carefully with the semi-classical limit and then the (Formula presented.) limit. For example, we numerically evaluate the ERE of two disjoint intervals for the large c Liouville field theory with (Formula presented.). We exploit the BPZ equation with the four twist operators, whose solution is given by the Heun function. We determine the ERE by tuning the behavior of the Heun function such that it becomes consistent with the geometry of the replica manifold. We find the same two saddle points as previous studies for (Formula presented.) in the above system. Then, we provide the ERE for the large but finite c and the (Formula presented.) in case that all the saddle points contribute comparably to the ERE. In particular, the ERE is the summation of these two saddle points by the same weight, due to the symmetry of the system. Based on this work, it shall be of interest to reconsider EE in other semi-classical physical systems with multiple saddle points.

    DOI： 10.3390/e24121758

    Web of Science

    Scopus

  5. Deep learning metric detectors in general relativity

    Katsube Ryota, Tam Wai-Hong, Hotta Masahiro, Nambu Yasusada

    PHYSICAL REVIEW D   Vol. 106 ( 4 )   2022.8

    　More details

    Language：Japanese   Publisher：Physical Review D  

    We consider conceptual issues of deep learning (DL) for metric detectors using test particle geodesics in curved spacetimes. Advantages of DL metric detectors are emphasized from a viewpoint of general coordinate transformations. Two given metrics (two spacetimes) are defined to be connected by a DL isometry if their geodesic image data cannot be discriminated by any DL metric detector at any time. The fundamental question of when the DL isometry appears is extensively explored. If the two spacetimes connected by the DL isometry are in superposition of quantum gravity theory, the postmeasurement state may be still in the same superposition even after DL metric detectors observe the superposed state. We also demonstrate metric-detection DL methods in 2dimensional anti-de Sitter (AdS) spacetimes to estimate the cosmological constants and Brown-Henneaux charges. In the AdS/CFT correspondence dictionary, it may be expected that such metric detectors in the AdS bulk region correspond to quantum measurement devices in the conformal field theory at the AdS boundary. +ACY-copy+ADs- 2022 American Physical Society.

    DOI： 10.1103/PhysRevD.106.044051

    Web of Science

    Scopus

  6. Leggett-Garg inequalities for testing quantumness of gravity

    Matsumura Akira, Nambu Yasusada, Yamamoto Kazuhiro

    PHYSICAL REVIEW A   Vol. 106 ( 1 )   2022.7

    　More details

    Language：Japanese   Publisher：Physical Review A  

    In this study, we determine a violation of the Leggett-Garg inequalities due to gravitational interaction in a hybrid system consisting of a harmonic oscillator and a spatially localized superposed particle. The violation of the Leggett-Garg inequalities is discussed using the two-time quasiprobability in connection with the entanglement negativity generated by gravitational interaction. It is demonstrated that the entanglement suppresses the violation of the Leggett-Garg inequalities when one of the two times of the quasiprobability t1 is chosen as the initial time. Further, it is shown that the Leggett-Garg inequalities are generally violated due to gravitational interaction by properly choosing the configuration of the parameters, including t1 and t2, which are the times of the two-time quasiprobability. The feasibility of detecting violations of the Leggett-Garg inequalities in hybrid systems is also discussed.

    DOI： 10.1103/PhysRevA.106.012214

    Web of Science

    Scopus

  7. Expanding Edges of Quantum Hall Systems in a Cosmology Language -- Hawking Radiation from de Sitter Horizon in Edge Modes

    Masahiro Hotta, Yasusada Nambu, Yuuki Sugiyama, Kazuhiro Yamamoto, Go Yusa

    PHYSICAL REVIEW D   Vol. 105 ( 10 )   2022.5

    　More details

    Language：Japanese   Publisher：AMER PHYSICAL SOC  

    Expanding edge experiments are promising to open new physics windows of
    quantum Hall systems. In a static edge, the edge excitation, which is described
    by free fields decoupled with the bulk dynamics, is gapless, and the dynamics
    preserve conformal symmetry. When the edge expands, such properties need not be
    preserved. We formulate a quantum field theory in 1+1 dimensional curved
    spacetimes to analyze the edge dynamics. We propose methods to address the
    following questions using edge waveforms from the expanding region: Does the
    conformal symmetry survive? Is the nonlinear interaction of the edge
    excitations induced by edge expansion? Do the edge excitations interact with
    the bulk excitations? We additionally show that the expanding edges can be
    regarded as expanding universe simulators of two-dimensional dilaton-gravity
    models, including the Jackiw-Teitelboim gravity model. As an application, we
    point out that our theoretical setup might simulate emission of analog Hawking
    radiation with the Gibbons-Hawking temperature from the future de Sitter
    horizon formed in the expanding edge region.

    DOI： 10.1103/PhysRevD.105.105009

    Web of Science

    Scopus

    arXiv

    Other Link： http://arxiv.org/pdf/2202.03731v2

  8. Alfvénic superradiance for a monopole magnetosphere around a Kerr black hole Reviewed

    Noda S., Nambu Y., Takahashi M., Tsukamoto T.

    Physical Review D   Vol. 105 ( 6 )   2022.3

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Physical Review D  

    Herein, we explore superradiance for Alfvén waves (Alfvénic superradiance) in an axisymmetric rotating magnetosphere of a Kerr black hole within the force-free approximation. On the equatorial plane of the Kerr spacetime, the Alfvén wave equation is reduced to a one-dimensional Schrödinger-type equation by separating variables of the wave function and introducing a tortoise coordinate mapping the inner and outer light surfaces to -∞ and +∞, respectively, and we investigate a wave scattering problem for Alfvén waves. An analysis of the asymptotic solutions of the wave equation and conservation of the Wronskian provides the superradiant condition for Alfvén waves, and it is shown that the condition coincides with that for the Blandford-Znajek process. This indicates that when Alfvénic superradiance occurs, the Blandford-Znajek process also occurs in the force-free magnetosphere. Then, we evaluate the reflection rate of Alfvén waves numerically and confirm that Alfvénic superradiance is indeed possible in the Kerr spacetime. Moreover, we will discuss a resonant scattering of Alfvén waves, which is related to a "quasinormal mode"of the magnetosphere.

    DOI： 10.1103/PhysRevD.105.064018

    Scopus

  9. Interferometry of black holes with Hawking radiation Reviewed

    Nambu Yasusada, Noda Sousuke

    PHYSICAL REVIEW D   Vol. 105 ( 4 )   2022.2

    　More details

    Authorship：Lead author   Language：English   Publisher：Physical Review D  

    We investigate the wave optical imaging of black holes with Hawking radiation. The spatial correlation function of Hawking radiation is expressed in terms of transmission and reflection coefficients for scalar wave modes and evaluated by numerically summing over angular quantum numbers for the Unruh-Hawking state of the Kerr-de Sitter black hole. Then, wave optical images of an evaporating black hole are obtained by the Fourier transformation of the spatial correlation function. For a short wavelength, the image of the black hole with the outgoing mode of the Unruh-Hawking state has the appearance of a star with its surface given by the photon sphere. It is found that interference between incoming modes from the cosmological horizon and reflected modes due to the scattering of the black hole can enhance brightness of images in the vicinity of the photon sphere. For a long wavelength, the entire field of view is bright, and the emission region of Hawking radiation cannot be identified.

    DOI： 10.1103/PhysRevD.105.045022

    Web of Science

    Scopus

  10. Qubit Clock in Quantum Cosmology Invited Reviewed

    Nambu Yasusada

    UNIVERSE   Vol. 8 ( 2 )   2022.2

    　More details

    Authorship：Corresponding author   Language：English   Publisher：Universe  

    We investigate the emergent time scenario in quantum cosmology based on the Page– Wotters approach. Using a quantum cosmological model with a qubit clock, it is demonstrated how the entanglement between the qubit clock and the geometry derives emergence of a time parameter, which defines evolution of the timeless quantum state of the universe. We show that the universe wave function conditioned by a qubit clock obeys the standard Schrödinger equation and the Fisher information for the clock state, which quantifies entanglement between the universe and the clock, and contributes as a negative energy density.

    DOI： 10.3390/universe8020099

    Web of Science

    Scopus

  11. Blandford-Znajek process as Alfvenic superradiance Reviewed

    Noda Sousuke, Nambu Yasusada, Tsukamoto Takuma, Takahashi Masaaki

    PHYSICAL REVIEW D   Vol. 101 ( 2 )   2020.1

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevD.101.023003

    Web of Science

  12. Wave optics in spacetimes with compact gravitating object Reviewed

    Nambu Yasusada, Noda Sousuke, Sakai Yuichiro

    PHYSICAL REVIEW D   Vol. 100 ( 6 )   2019.9

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevD.100.064037

    Web of Science

  13. Large scale quantum entanglement in de Sitter spacetime Reviewed

    Matsumura Akira, Nambu Yasusada

    PHYSICAL REVIEW D   Vol. 98 ( 2 )   2018.7

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevD.98.025004

    Web of Science

  14. Soft-Hair-Enhanced Entanglement Beyond Page Curves in a Black Hole Evaporation Qubit Model Reviewed

    Hotta Masahiro, Nambu Yasusada, Yamaguchi Koji

    PHYSICAL REVIEW LETTERS   Vol. 120 ( 18 )   2018.5

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevLett.120.181301

    Web of Science

  15. Harvesting Large Scale Entanglement in de Sitter Space with Multiple Detectors Reviewed

    Kukita Shingo, Nambu Yasusada

    ENTROPY   Vol. 19 ( 9 )   2017.9

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/e19090449

    Web of Science

  16. Classical and quantum correlations of scalar field in the inflationary universe Reviewed

    Y. Nambu, Y. Ohsumi

    Phys. Rev. D   Vol. 84 ( 4 ) page： 044028   2011.7

    　More details

    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  17. One-dimensional Force-free Numerical Simulations of Alfven Waves around a Spinning Black String

    Koide Shinji, Noda Sousuke, Takahashi Masaaki, Nambu Yasusada

    ASTROPHYSICAL JOURNAL   Vol. 928 ( 1 )   2022.3

    　More details

    Language：Japanese   Publisher：Astrophysical Journal  

    We performed one-dimensional force-free magnetodynamic numerical simulations of the propagation of Alfvén waves along magnetic field lines around a spinning black-hole-like object, the Banados-Teitelboim-Zanelli black string, to investigate the dynamic process of wave propagation and energy transport with Alfvén waves. We considered an axisymmetric and stationary magnetosphere and perturbed the background magnetosphere to obtain the linear wave equation for the Alfvén wave mode. The numerical results show that the energy of Alfvén waves monotonically increases as the waves propagate outwardly along the rotating curved magnetic field line around the ergosphere, where energy seems not to be conserved, in the case of energy extraction from the black string by the Blandford-Znajek mechanism. The apparent breakdown of energy conservation suggests the existence of a wave induced by the Alfvén wave. Considering the additional fast magnetosonic wave induced by the Alfvén wave, the energy conservation is confirmed. Similar relativistic phenomena, such as the amplification of Alfvén waves and induction of fast magnetosonic waves, are expected around a spinning black hole.

    DOI： 10.3847/1538-4357/ac47f8

    Web of Science

    Scopus

  18. Tripartite entanglement of Hawking radiation in dispersive model Reviewed

    Yasusada Nambu and Yuki Osawa

    Physical Review D   Vol. 103   page： 125007   2021.6

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： https://doi.org/10.1103/PhysRevD.103.125007 I.

  19. Violation of Bell-CHSH Inequalities through Optimal Local Filters in the Vacuum Invited Reviewed

    Quantum Reports   Vol. 2   page： 542 - 559   2020.11

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

  20. Null Wave Front and Ryu-Takayanagi Surface Reviewed

    Tsujimura Jun, Nambu Yasusada

    ENTROPY   Vol. 22 ( 11 )   2020.11

    　More details

    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/e22111297

    Web of Science

  21. Squeezing of Primordial Gravitational Waves as Quantum Discord Reviewed

    Matsumura Akira, Nambu Yasusada

    UNIVERSE   Vol. 6 ( 2 )   2020.2

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/universe6020033

    Web of Science

  22. Clock Time in Quantum Cosmology Reviewed

    Rotondo Marcello, Nambu Yasusada

    UNIVERSE   Vol. 5 ( 2 )   2019.2

    　More details

    Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/universe5020066

    Web of Science

  23. Propagation of scalar field in AdS space-time

    Tsujimura Jun, Numbu Y.

    Meeting Abstracts of the Physical Society of Japan   Vol. 74.2 ( 0 ) page： 367 - 367   2019

    　More details

    Language：Japanese   Publisher：The Physical Society of Japan  

    DOI： 10.11316/jpsgaiyo.74.2.0_367

    CiNii Research

  24. Quantum circuit model of black hole evaporation Reviewed

    Tokusumi Tomoro, Matsumura Akira, Nambu Yasusada

    CLASSICAL AND QUANTUM GRAVITY   Vol. 35 ( 23 )   2018.12

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6382/aaeb5a

    Web of Science

  25. The Decoherence and Interference of Cosmological Arrows of Time for a de Sitter Universe with Quantum Fluctuations Reviewed

    Rotondo Marcello, Nambu Yasusada

    UNIVERSE   Vol. 4 ( 6 )   2018.6

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/universe4060071

    Web of Science

  26. Quantum discrimination for the universe

    Matsumura A.

    Proceedings of the 28th Workshop on General Relativity and Gravitation in Japan, JGRG 2018   Vol. 2   page： 68 - 76   2018

    　More details

    Publisher：Proceedings of the 28th Workshop on General Relativity and Gravitation in Japan, JGRG 2018  

    Scopus

  27. Qubit Model of Black Hole Evapolation

    Tokusumi Tomoro

    Meeting Abstracts of the Physical Society of Japan   Vol. 73.1 ( 0 ) page： 446 - 446   2018

    　More details

    Language：Japanese   Publisher：The Physical Society of Japan  

    DOI： 10.11316/jpsgaiyo.73.1.0_446

    CiNii Research

  28. Entanglement dynamics in de Sitter spacetime Reviewed

    Kukita Shingo, Nambu Yasusada

    CLASSICAL AND QUANTUM GRAVITY   Vol. 34 ( 23 )   2017.12

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1088/1361-6382/aa8e31

    Web of Science

  29. Quantum Cramer-Rao Bound for a Massless Scalar Field in de Sitter Space Reviewed

    Rotondo Marcello, Nambu Yasusada

    UNIVERSE   Vol. 3 ( 4 )   2017.12

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.3390/universe3040071

    Web of Science

  30. Analog rotating black holes in a magnetohydrodynamic inflow Reviewed

    Noda Sousuke, Nambu Yasusada, Takahashi Masaaki

    PHYSICAL REVIEW D   Vol. 95 ( 10 )   2017.5

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1103/PhysRevD.95.104055

    Web of Science

  31. Probability of boundary conditions in quantum cosmology Reviewed

    Suenobu Hiroshi, Nambu Yasusada

    GENERAL RELATIVITY AND GRAVITATION   Vol. 49 ( 2 )   2017.2

    　More details

    Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

    DOI： 10.1007/s10714-017-2185-z

    Web of Science

  32. Probability of boundary conditions in quantum cosmology

    Nambu Yasusada, Suenobu Hiroshi

    8TH INTERNATIONAL WORKSHOP DICE2016: SPACETIME - MATTER - QUANTUM MECHANICS   Vol. 880   2017

    　More details

  33. Qubit model of hawking radiation

    Tokusumi T.

    Proceedings of the 27th Workshop on General Relativity and Gravitation in Japan, JGRG 2017   Vol. 3   page： 77 - 78   2017

    　More details

    Publisher：Proceedings of the 27th Workshop on General Relativity and Gravitation in Japan, JGRG 2017  

    Scopus

  34. 宇宙初期ゆらぎのエンタングルメント Invited Reviewed

    南部保貞

    日本物理学会誌   Vol. 11   page： 763-770   2014.11

    　More details

    Authorship：Lead author   Language：Japanese  

  35. 「光子の裁判」と宇宙の古典性 Invited Reviewed

    南部保貞

    数理科学   Vol. 1   page： 45-50   2014.1

    　More details

    Authorship：Lead author   Language：Japanese  

  36. Viewing black holes by waves Reviewed

    K. Kanai, Y. Nambu

    Class. Quantum Grav.   Vol. 30 ( 17 ) page： 175002   2013.6

    　More details

    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  37. Entanglement structure in expanding universe Invited Reviewed

    Yausada Nambu

    Entropy   Vol. 15 ( 5 ) page： 1847-1878   2013.5

    　More details

    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

  38. Wave optics and image formation in gravitational lensing Reviewed

    Y. Nambu

    Int. J. Astro. Astrophyisics   Vol. 3 ( 1 ) page： 1-7   2013.3

    　More details

    Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

▼display all

To the head of Papers.▲

Books 1

  1. 数理科学特集「宇宙の謎と魅力」：量子情報で理解する宇宙 Reviewed

    南部保貞（ Role： Sole author）

    2022.7 

    　More details

    Language：Japanese

To the head of Books.▲

Presentations 15

  1. 時空構造と量子論 Invited

    南部保貞

    第１回極限宇宙スクール  2022.3 

    　More details

    Event date： 2022.3

    Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

    Venue：基礎物理学研究所  

  2. Entanglement partner of super horizon modes Invited International conference

    Yasusada Nambu

    Recent progress in theoretical physics based on quantum information theory  2021.3.5 

    　More details

    Event date： 2021.3

    Language：English   Presentation type：Oral presentation (keynote)  

  3. Multipratite entanglement in black hole evaporation and primordial fluctuations Invited International conference

    Yasusada Nambu

    Relativistic Quantum Information North 2019  2019.5.31 

    　More details

    Event date： 2019.5

    Language：English   Presentation type：Oral presentation (keynote)  

  4. インフレーションの数理：原始ゆらぎの量子性 Invited

    南部保貞

    日本物理学会  2019.3.15 

    　More details

    Event date： 2019.3

    Language：Japanese   Presentation type：Oral presentation (keynote)  

    Venue：九州大学  

  5. Interferometry of black holes with Hawking radiation Invited

    南部保貞

    ブラックホール磁気圏研究会  2022.3.10 

    　More details

    Event date： 2022.3

    Language：Japanese   Presentation type：Oral presentation (keynote)  

    Venue：大阪市立大学  

  6. 流体ブラックホールにおけるHawking輻射の量子もつれ構造 Invited

    南部保貞

    中央大学素粒子論研究室セミナー  2022.1.13 

    　More details

    Event date： 2022.1

    Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

  7. 流体ブラックホールにおけるHawking輻射の量子もつれ構造 Invited

    南部保貞

    大阪市立大学セミナー  2021.5.10 

    　More details

    Event date： 2021.5

    Language：Japanese   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

  8. 流体ブラックホールにおけるHawking輻射の量子もつれ構造 Invited

    南部保貞

    ブラックホール磁気圏研究会  2021.3.25 

    　More details

    Event date： 2021.3

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

    Venue：名古屋大学  

  9. 初期宇宙とエンタングルメント Invited

    南部保貞

    九州大学理学部談話会  2020.10.6 

    　More details

    Event date： 2020.10

    Language：Japanese  

    Venue：九州大学理学部  

  10. 宇宙論とエンタングルメント Invited

    南部保貞

    量子情報技術研究会  2018.6.5 

    　More details

    Event date： 2018.6

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

    Venue：広島国際会議場  

  11. 宇宙初期のエンタングルメントとBell不等式 Invited

    南部保貞

    弱値，エンタングルメント，量子コヒーレンスの新地平  2018.2.21 

    　More details

    Event date： 2018.2

    Language：Japanese   Presentation type：Oral presentation (invited, special)  

    Venue：KEK  

  12. Stochastic Inflation, Entanglement and Bell’s inequality Invited

    Yasusada Nambu

    IR workshop  2018.1.21 

    　More details

    Event date： 2018.1

    Language：English   Presentation type：Oral presentation (keynote)  

  13. BZ processとsuperradiance Invited

    南部保貞

    BZ研究会  2017.9.29 

    　More details

    Event date： 2017.9

    Language：Japanese   Presentation type：Oral presentation (keynote)  

  14. Stochastic Inflation, Entanglement and Bell's Inequalities Invited International conference

    南部 保貞

    Infrared physics of gauge theories and quantum dynamics of inflation  2018.1.21 

    　More details

    Language：English   Presentation type：Oral presentation (invited, special)  

    Venue：琵琶湖クラブ  

  15. Multipartite Entanglement in Black Hole Evaporation and Primordial Fluctuations Invited International conference

    南部 保貞

    Relativistic Quantum Information North  2019.5.31 

    　More details

    Language：English   Presentation type：Oral presentation (keynote)  

    Venue：台南成功大学  

▼display all

To the head of Presentations.▲

KAKENHI (Grants-in-Aid for Scientific Research) 5

  1. Entanglement structure and information scrambling in inflationary models

    Grant number：22H05257  2022.6 - 2024.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Transformative Research Areas (A)

    　 More details

    Authorship：Principal investigator 

    Grant amount：\2600000 （ Direct Cost: \2000000 、 Indirect Cost：\600000 ）

  2. Quantumness and multipartite entanglement in primordial fluctuation

    Grant number：19K03866  2019.4 - 2023.3

    　 More details

    Authorship：Principal investigator 

    Grant amount：\4420000 （ Direct Cost: \3400000 、 Indirect Cost：\1020000 ）

  3. 宇宙初期ゆらぎの量子性と情報量

    Grant number：16H01094  2016.4 - 2018.3

    科学研究費補助金   新学術領域研究(研究領域提案型)

    南部 保貞

    　 More details

    Authorship：Principal investigator 

    Grant amount：\2080000 （ Direct Cost: \1600000 、 Indirect Cost：\480000 ）

    インフレーション宇宙における情報量，エンタングルメントならびに量子古典転移に関する研究を行い以下の成果を得た．
    <BR>
    (1)多体間エンタングルメントの効果：deSitter時空上での２つの検出器間のエンタングルメントは，距離がハッブル地平線長さを超えると消失することが知られていた．これはインフレーションによって大スケールの古典ゆらぎが生成されるというシナリオと整合的である．本解析では多数個（３個以上）の検出器間のエンタングルメントを評価しその結果，多体間エンタングルメントは大スケールにおいても残り得ることを示した．この結果は，原始ゆらぎの古典性についての再考察を必要とするものである．
    <BR>
    (2)deSitter時空におけるFisher情報量：de Sitter時空上の量子場に対する古典Fisher情報量ならびに量子Fisher情報量を評価し，場の持つエンタングルメントとこれらの情報量の振る舞いの関係性を議論した．
    29年度が最終年度であるため、記入しない。
    29年度が最終年度であるため、記入しない。

  4. Wave optical effect in black hole spacetimes

    Grant number：15K05073  2015.4 - 2019.3

    Nambu Yasusada

    　 More details

    Authorship：Principal investigator 

    Grant amount：\4680000 （ Direct Cost: \3600000 、 Indirect Cost：\1080000 ）

    To discriminate black hole mimikers of which radius is smaller than unstable photon orbit, we investigate wave optics in spherically symmetric spacetimes with compact gravitating object. We found that the effect of star's surface smaller than the radius of unstable photon orbit results in oscillation in power spectrums with long period, which make possible to discriminate black hole mimickers from black hole.

  5. Educational activities and its evaluation using the Galactic Center Supermassive Black Hole Sgr A * Events

    Grant number：26350255  2014.4 - 2018.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    OHNISHI Kouji, MINESHIGE Shin, TAKAHASHI Masaaki, MIYOSHI Makoto, NISHIYAMA Shogo, TAKAHAHI Rohta, KINUGASA Kenzo, SAITO Masao, NISHIOKA Makiko, IDE Hidemi, NAITO Seiichiro, SUSUKI Yukino, HOTTA Hideyuki, KOMINAMI Junko, KIUCHI Kenta, OHSUGA Ken, YOSHIDA Naoki, SAIDA Hiromi, KAWASHIMA Tomohisa, NAMBU Yasusada, TAKAMORI Yosuke, TAMURA Takayuki, HADA Kazuhiro, AKIYAMA Kazunori, HATANO Satomi, SINOHARA Hideo, ARIMOTO Junichi, WATARAI Kenya, SAITO Hideki, OHBA Toru, HIDAKA Masaki, TAKEURA Siro, TAKAHASHI Jun, HONMA Takayuki, NEMOTO Shiomi, TOYOMASU Shinji, TUKADA Ken

    　 More details

    The purpose of this research is to share understanding and dissemination of scientific research methods to citizens by sharing astronomical research sites in real time with researchers, educators and citizens. For this purpose, we made a mechanism to experience and share the science scene for citizens, children and students, and at the same time conducted an experiment to create science education scenes by collaboration and cooperative work of researchers and educators. In this practice, we initially targeted the Sgr A * event, then Exoplanets Naming campaign, fusion of astronomy and art, latest astronomy WS, gravitational wave detection, "Nagano prefecture is Astro-prefecture" and so on.
    In the process of creating a network of researchers, educators, and citizens, we took the opportunity to practice a new science education that stakeholders shared scientific thoughts together.

To the head of KAKENHI (Grants-in-Aid for Scientific Research).▲
 

Teaching Experience (On-campus) 2

  1. 一般相対論

    2017

  2. Fundamentals of Physics II

    2011

To the head of Teaching Experience (On-campus).▲

Teaching Experience (Off-campus) 5

  1. 時空の物理における量子情報

    2020.10 （Kyushu University）

    　More details

    Level：Postgraduate 

  2. 時空の物理における量子情報

    2018.7 （Rikkyo University）

    　More details

    Level：Postgraduate 

  3. 物理数学

    （Nagoya University）

  4. 解析力学

    （Nagoya University）

  5. 電磁気

    （Nagoya University）

To the head of Teaching Experience (Off-campus).▲
 

Social Contribution 1

  1. スーパーサイエンスハイスクール

    Role(s)：Lecturer,　Advisor,　Informant

    名古屋大学附属高校  名古屋大学附属高校  2014.4

    　More details

    Audience： Junior students,　High school students

    Type：Visiting lecture

To the head of Social Contribution.▲