Seminars

2009

GCOE seminar
title
Quantum opto-mechanics using an optically levitated nanosphere
author
Darrick E. Chang
California Institute of Technology)
date
March 24 (Wed) 2010, 14:00-15:30
place
Room 115[1F],Graduate School of Science, Building 5
abstract
ne of the most intriguing questions associated with quantum theory is whether effects such as quantum coherence and entanglement can be observed at macroscopic scales. As a first step towards resolving this question, recently much effort has been directed toward quantum state preparation of high-Q modes of nano-mechanical oscillators -- in particular, cooling such modes to their quantum ground state. To reach the quantum regime, it is necessary to minimize the thermalization and decoherence rates of these systems, which thus far has necessitated the use of cryogenic operating environments. Here we propose a fundamentally different approach, where one optically levitates an entire mechanical system inside an optical cavity, thus eliminating any contact of the system with the environment through clamping or material supports. Such an approach should facilitate the emergence of quantum behavior even in room-temperature environments. In particular, we show theoretically that the center-of-mass motion of an optically levitated nanosphere can be laser-cooled to its quantum ground state starting from room temperature. We also describe a technique to transfer quantum states of motion onto light or vice versa. This can be used to entangle two spheres separated by large distances in different cavities, starting from a pair of entangled optical beams generated using conventional nonlinear optics. Conversely, the optical trapping fields can be manipulated to create highly non-classical states of motion, which subsequently can be mapped onto light. As two examples, we show that an optically levitated sphere can be used to generate squeezed states of light and single photons. These examples suggest tremendous potential to realize nonlinear optical processes or quantum information processing of light using opto-mechanical systems.
contact
Takao Aoki ( takao.aoki@scphys. kyoto-u.ac.jp, Tel:075-753-3804)
note
GCOE Lecture
title
Cosmology Today
author
Professor George F. Smoot
University of California at Berkeley
date
Feb. 22 (Mon), 2010, 16:30 - 18:00
place
Room 301[3F],Graduate School of Science, Building 6
abstract
Using our most advanced techniques and instruments we sift through relic clues and evidence to understand the events surrounding the birth and subsequent development of the Universe. A precision inspection and investigation of the Cosmic Scene along with careful analysis, discussion, and computer modeling have allowed us determine what happened over billions of years with amazing certainty and accuracy. Some of our findings are surprising and even provide shocking twists of plot. There remain even additional mysteries to be solved. In spite of that we can tell the tale of the creation and history of the Universe show key supporting evidence some of it from very early times including using the cosmic background light to provide a direct image of the embryo universe and new techniques to reveal dark matter and dark energy.
contact
Hikaru Kawai( gcoe-office@scphys.kyoto-u.ac.jp, Tel:075-753-3758)
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GCOE seminar
title
Opportunities for neutron beam research at Australia's OPAL reactor
author
Dr. S J Kennedy
(echnical Director, Bragg Institute Australian Nuclear Science & Technology Organisation)
date
Feb. 10 (Wed), 2010, 14:30-15:30
place
Room 115 [1F], Physics Department
abstract
Neutron scattering has evolved over more than 1/2 century into a powerful set of tools for determination of atomic and molecular structures. Modern neutron sources, such as the OPAL research reactor at ANSTO, offer the chance to determine complex structures over length scales from ~0.1 nm to ~10 μm, information on atomic and molecular dynamics, on magnetic interactions and on the location and behaviour of light elements and gases (such as hydrogen) in a broad variety of materials. Consequently, neutron scattering has found a niche at the forefront of condensed matter research.
The presentation will outline the strengths of neutron scattering, describe the OPAL research reactor, and provide an overview of the opportunities for experimental research, including highlights from recent experiments. The discussion will emphasize how university researchers can utilize these exciting new facilities.  
contact
Yoshihisa Iwashita iwashita@kyticr. kuicr.kyoto-u.ac.jp, Tel:0774-38-3282
GCOE seminar
title
The self-organization of macromolecules with amphiphilic monomer units and in crowding environment
author
Professor Valentina Vasilevskaya
(Nesmeyanov Institute of Organoelement Compounds RAS)
date
Jan. 22 (FRI), 2010, 10:30 - 12:00
place
Room 401[4F], Physics Department
abstract
The self-organization of two types of polymer system will be discussed. First, we consider the macromolecules composed of amphiphilic monomer units having both hydrophobic and hydrophilic groups. Secondly, we address the polyelectrolyte macromolecules in crowding environment. The results of our collaboration with the laboratory of Professor K.Yoshikawa (Kyoto University) during last year will be presented as well. Namely, we present results of computer modeling of amphiphilic AP macromolecules and a theory of DNA compactization in solution of BSA (bovine serum albumin). By means of the computer modeling we studied the coil-to-globule transition of macromolecules composed of hydrophilic P and amphiphilic A monomer units. It was shown that inner structure of a globule of such AP macromolecules depends on the radius of action of potential. In case of the long-ranged potential the globule has blob-like structure, while in case of short-ranged potential the backbone of macromolecules forms the helix structure with a variable direction of bending. In the latter case, the compactization of AP macromolecules proceeds through the formation necklace conformation with quasi-helix beads. The theory of DNA compactization in crowding of strongly charged BSA molecules was created. It was proposed that the main factors governing the conformation of DNA are the depletion effect and the strong electrostatic repulsion between BSA and DNA molecules. It was shown that at low salt concentration with increase of the BSA concentration DNA at first contracts smoothly and then undergoes the sharp jump-wise transition; the concentration of BSA in the point of this transition depends on the salt concentration. It was also shown, that the higher the salt concentration, the smoother the transition. 
contact
Kenichi Yoshikawa ( yoshikaw@scph ys.kyoto-u.ac.jp, Tel:075-753-3671)
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GCOE/YITP Lecture
title
Topological Defects in Cosmology and Condensed Matte
author
Tom Kibble
(Imperial College, London)
date
January 15, 2010 (Fri) 16:30-
place
Panasonic Auditorium, Yukawa Hall, Yukawa Institute, Kyoto University
abstract
I shall briefly review the conditions under which topological defects may be expected to form at a symmetry-breaking phase transition, either in the early Universe or in low-temperature condensed-matter systems. Methods of estimating the density of defects produced by cooling through the transition at a finite rate, which were first developed in a cosmological context, have led to very innovative developments in condensed matter. These ideas have been tested in experiments in superfluids, liquid crystals, superconductors, and various other systems. I shall describe these developments and review the current status of the experiments. On the cosmological side, there is as yet no firm observational evidence for the existence of topological defects. Recent suggestions that a cosmic string might have been detected by its gravitational lensing effect have proved unfounded. On the other hand, the theoretical arguments for their existence have been strengthened by the discovery that cosmic strings of various kinds appear naturally in superstring theory. There are thus good grounds for optimism about their future detection.
contact
Prof. Misao Sasaki, YITP, (ext: 7043)
note
http://www.yukawa.kyoto-u.ac.jp/contents/seminar/detail.php?SNUM=50940
GCOE seminar
title
The Digital Universe 3D Atlas
author
Dr. Carter Emmart
(Rose Center for Earth and Space at the American Museum of Natural History, New York, USA)
date
December 14, 2009 (Mon) 13:00-14:00
place
Meeting Room[5F], Department of Astronomy
abstract
The Digital Universe (DU) is an ongoing project at the American Museum of Natural History (AMNH) to accurately create a 3D data atlas of the cosmos, started with NASA funding in 1998. DU was conceived as the basis for making immersive planetarium space shows in full dome graphics from data visualization. The techniques necessary to display the true scale range of the universe in a continuous, exponential manner present to common audiences a visual equivalence of the mathematical convention of scientific notation. While planetarium shows traditionally explore the macro realm beyond Earth, any scale is within reach of such techniques, opening up a challenge for standards of 3D data that might be accommodated into a global library of content that spans the entire scale range of current knowledge. Examples from DU will be shown in Uniview, one such software technique developed as an academic collaboration between AMNH and Linkoping University in Sweden, and the Swedish company SCISS was founded to support Uniview as a commercial product. A central concept of Uniview is simultaneous, multiple user capability with identical content viewed on single screen or in dome displays. Such communication abilities enable remote connection between authorities, audiences and classrooms with the goal of linking the concept of DU and demonstrating current understanding from science across the cultures of the world.
http://www.haydenplanetarium.org/universe
contact
Kazunari Shibata(shibata@kwasan.kyoto-u.ac.jp, ext 3893)
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GCOE・YITP seminar (Condensed matter physics)
title
Aggregation & Fragmentation Kinetics in Granular Gases
author
Anna Bodrova
(Moscow State University)
date
July 15, 2009 (Wed) 4:00 p.m.
place
Seminar Room K202, Yukawa Institute, Kyoto University
abstract
Aggregation and fragmentation are important processes, which play a key role in many astrophysical systems. Formation of planets and planetesemals, evolution of interstellar dust clouds and planetary rings, such as Saturnian Rings, etc. may serve as representative examples. We discuss simplified theoretical models of ballistic of aggregation and fragmentation, which nevertheless describe the most salient properties of real systems. We study evolution of granular gases with fragmentation and aggregation along with the properties of the steady state. Analytical results are compared with the numerical solutions of the respective rate equations and with the results of the Monte-Carlo simulations. A good agreement between the theory and simulations is observed. Application of the theory to the experimental data for the planetary rings of Saturn is discussed.
contact
note
GCOE seminar
title
Tidal Tails
author
Prof. D.C. Heggie
(University of Edinburgh)
date
July 10 (Fri), 2009,  16:00 -
place
Room 531[5F], Building No.1
abstract
Galactic satellites and globular star clusters are observed to lose stars along narrow streams called 'tidal tails'. In a few cases the distribution of stars along the streams is irregular (clumpy). In this seminar I first review the dynamics underlying the formation and evolution of tidal tails. Then I show that clumpy structures can arise even when the rate of escape is steady; they do not imply that the rate of loss of mass is time-dependent.
contact
Shin Mineshige
note
GCOE・YITP seminar (Particle Physics seminar)
title
Control and readout of the electron spin of individual dopant atoms in silicon
author
Laszlo Feher
(Budapest, RMKI and Szeged U.)
date
June 24, Wednesday, 1:30 p.m.
place
Conference Room Y306, Yukawa Hall, Yukawa Institute, Kyoto University
abstract
Two integrable many-body problems are called dual to each other if the action variables of model i) are the particlecoordinates of model ii), and vice versa. It has been found by S. Ruijsenaars between 1989-95 that the ‘Calogero type’one-dimensional many-body models form dual pairs in the above sense. We discuss a group theoretic interpretation of the duality focusing on a relatively simple example. The talk is based on a joint paper with C. Klimcik, available as arXiv:0901.1983.
contact
Naoki Sasakura (Yukawa Theoretical Institute for Physics) (ext, 7037)
GCOE・YITP seminar (Condensed matter physics)
title
Combination of FTLM and DMRG for dynamics at finite temperature
author
Jure Kokalj
(Budapest, RMKI and Szeged U.)
date
June 22, 2009 (Monday) 4:00 p.m.
place
Seminar Room K202, Yukawa Institute, Kyoto University
abstract
Study of strongly correlated systems still poses unanswered fundamental questions regarding conductivity at finite temperature, e.g. the relation between integrability and ballistic transport. This however reflects the lack of sufficiently accurate methods for calculation of finite temperature dynamics and poses serious challenges to the numerical studies. I will present new method, which is a combination of FTLM and DMRG, and is used for calculation of dynamical properties of one dimensional systems at finite temperature. As a test and demonstration I will show some
contact
note
GCOE Seminar
title
Control and readout of the electron spin of individual dopant atoms in silicon
author
Dr. Andrea Morello
(Australian Research Council Centre of Excellence for Quantum Computer Technology and School of Electrical Engineering and Telecommunication, The University of New South Wales, Sydney, Australia)
date
June 12 (FRI), 2009, 16:00 - 17:00
place
Room 401 [4F], Physics Department
abstract
Silicon is an ideal host for donor-based electron spin qubits. It can be isotopically purified to eliminate nuclear spins and obtain long electron spin coherence, and the negligible spin-orbit coupling ensures extremely long relaxation times. Here I will review our latest results on the control and readout of the electron spin state of a single dopant atom in silicon. We have developed CMOS-compatible devices that combine a novel type of Single-Electron Transistor (SET) [1] with individually implanted phosphorus atoms [2] and a local Electron Spin Resonance line [3]. This scheme allows single-shot readout of an individual donor electron while minimizing the back-action of the charge sensor. For the first time we have a structure where the donor and the SET are tunnel-coupled, yielding very high charge transfer signals [4]. As an alternative, we have demonstrated resonant charge tunneling through a single P atom by transport experiments, whereby the energy levels and the Zeeman splitting of a single donor can be studied in detail.
[1] S. J. Angus, A. J. Ferguson, A. S. Dzurak, and R. G. Clark, Appl. Phys. Lett. 92, 112103 (2008).
[2] D. N. Jamieson et al., Appl. Phys. Lett. 86, 202101 (2005).
[3] L. H. Willems van Beveren et al., Appl. Phys. Lett. 93, 072102 (2008).
[4] A. Morello et al., arXiv:0904.1271 (2009).
contact
Yoshi Maeno(maeno@scphys.kyoto-u.ac.jp ・ext 3783)
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GCOE Seminar
title
The H, P, T phase diagram of URu2Si2 P and H switch of ground states
author
Prof. Jacques Flouquet (INAC/SPSMS CEA-Grenoble)
date
26th May (Tue), 2009, 14:30 - 15:30
place
The 4th Lecture Hall [5F], Physics Department
abstract
We will describe macroscopic and microscopic studies recently performed in Grenoble. Inelastic neutron scattering experiments give a clear view of the (P, H) response in the low pressure hidden order (HO) phase and in the high pressure antiferromagnetic (AF)phase. The main proposals are
- both ordered phases have the same wave vector Q=(0,0,1),
- the resonance at Q=(1,0,0) collapses when superconductivity (SC)collapses.
An amusing effect is the H reentrance of HO from AF as in this Ising type system. AF does not disappear via metamagnetism. Other examples of H reentrance phenomena in heavy fermion systems will be briefly reported: AF in SC (CeRhIn5) - SC in the ferromagnet URhGe
contact
Kenji Ishida(kishida@sc phys.kyoto-u.ac.jp・ext 3752)
note

GCOE Seminar (Astrophysics)
title
“Gravitational self-force”(with application to extreme-mass-ratio binary inspirals)
author
Leor Barack (University of Southampton)
date
May 14, Thursday 4:00 p.m. 〜
place
Conference Room Y206, Yukawa Hall, Yukawa Institute, Kyoto University6
abstract
The radiative inspiral of compact stellar-mass objects into massive black holes in galactic nuclei is a key source for LISA - the proposed space-based gravitational wave observatory. Each of these inspiralling objects is an extremely effective probe of the strong-field geometry of the central black hole, and its gravitational wave signal encodes a wealth of detailed information about this geometry. Decoding this information will require accurate theoretical templates of the gravitational waveforms, which, in turn, requires an accurate model of the orbital evolution. The inspiral dynamics can be described in a perturbative fashion in terms of an effective gravitational self-force. Knowledge of the local self force acting on the inspiralling body is an important prerequisite in the program to model astrophysical inspirals. I will begin this talk by reviewing the general theory of the gravitational self-force in curved spacetime, and proceed to describe how this theory is being applied today in actual calculations of the self force for inspiral orbits. As a particular application, I will present a recent calculation of the shift in the location and frequency of the ISCO (innermost stable circular orbit) of a Schwarzschild black hole due to the conservative piece of the gravitational self force.
contact
note

GCOE seminar
title
Emergent electronic states in superconductors on the border of magnetism
author
Professor Christos Panagopoulos
(Department of Physics and FORTH, University of Crete, Heraklion, Greece and Department of Physics and Applied Physics, Nanyang Technological University, Singapore)
date
April. 16 (THU), 2009, 10:00 - 11:30
place
Room 401 [4F], Physics Department
abstract
I will discuss the emergence of novel electronic states of matter as probed by several experimental techniques. These states lead to a common phase diagram in several unconventional superconductors on the border of magnetism, including heavy fermions and copper oxides. Key features directing new materials towards unconventional high temperature superconductors will be addressed.
contact
Yoshi Maeno, maeno@scphys.kyoto-u.ac.jp ext 3783
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