vol. 116 | iTHES

Vol. 116, February 29th, 2016


  • Upcoming Events
  • Paper of the week

Paper of the week

J. Robert Johansson


Landau-Zener-Stueckelberg-Majorana interferometry in a semiconductor device

From the Office

The office of iTHES assistant, Ms.Chikako Oota is situated at the second floor of the main research building, room # 246. The extension number is 3261. She will be at the office from 10 a.m. to 16 p.m.

Upcoming Events

The 8th iTHES Academic-Industrial Innovation Lecture
Date: March 1st (Tue.)
Place: Nishina Hall, Wako, RIKEN
Company: JSOL

iTHES one-day workshop "Storage Rings and Tests of Fundamental Symmetries"

Date: Mar. 2 (Wed) 10:00-
Place: room 535 (Main research building) 

Invited speakers are:
Makiko Nio (RIKEN)
Daisuke Nomura (YITP)
Masashi Otani (KEK)
Yannis K. Semertzidis (KAIST/IBS)
Koichiro Shimomura (KEK)
Yasunori Yamazaki (RIKEN)

For detail, please see
The registration is not needed for the participation to the workshop.

“ICA (Independent Component Analysis) and the Big Bang”

Date: March 3(Thursday), 2016, 15:00 - 17:00
Place: 3F S305 seminar room, BSI Central Building
Speaker: Prof. Jean-Francois Cardoso
(Telecom ParisTech/CNRS, University Paris 7, Cosmology)

In 2013, the Planck collaboration from the European Spatial Agency released its first results and products, including a full-sky high-resolution map of the Cosmic Microwave Background (CMB) which made the headlines of newspapers worldwide. Indeed, that image is quite literally a snapshot of our Universe in its infancy, when it was a promising but fragile baby, only 380.000 years old. The CMB map is obtained by combining the 9 frequency channels of the Planck satellite in order to separate the precious relic radiation from many other astrophysical emissions. This is a source separation issue which, as it turned out, was best solved by a blind method -- in other words, by ICA:
Independent Component Analysis-- carefully crafted to deal with the uncertainties in the sky and the wild SNR conditions in the data.
The talk will start with an introduction to Big Bang theory, the standard cosmological model, so beautifully supported by Planck results. I will then describe the Planck satellite and sketch its data processing pipeline up to the inference of the cosmological parameters. I will focus on my main contribution to it: blind separation of the CMB from all the other emissions by an ICA algorithm based on a Gaussian spectral likelihood.

Host: Shun-ichi Amari
Lab. for Mathematical Neuroscience (ext. 7142)

12th International Conference on Low Energy Antiproton Physics (LEAP2016)
Date: March 6-11, 2016
Place: Kanazawa Japan

The intent of LEAP 2016 is to actively stimulate the overlap and dialogue between various research forefronts in the diversified field of antiproton physics and related field involving meson and baryon with strangeness.
iTHES is a cosponsor of this meeting.
Feel free to join !

"LIGO Gravitational Wave Detection Seminar"
Date: March 7 (Mon) 2016 16:00-
Place: BSI Ikenohata Building, 3rd floor, large conference room
Speaker: Prof. Kipp Cannon (RESCEU, The Univ. of Tokyo; LIGO member)
Contact: Kazuo Maxima (maxima@phys.s.u-tokyo.ac.jp)

iTHES Symposium
Baymfest in Tokyo:
"Exploring Extreme Forms of Matter - A symposium in honor of Professor Gordon Baym -"
Date: March 14 (Mon) 2016. 10:00am-
Place: Faculty of Science 4th-bldg 1320, Department of Physics, The University of Tokyo

This is a joint symposium hosted by The University of Tokyo and RIKEN on nuclear physics, condensed matter physics and astrophysics in hornor of Prof. Gordon Baym's 80th birth year. We welcome participation of all scientists who are interested in these fields and related interdisciplinary research. We hope to have fruitful discussions on the current status and future perspectives in these fields at the symposium.

3rd mini-symposium on Computations, Brains and Machine
Date: March 17, 2016, 1:30 pm -
Place: the seminar room, 1F, at BSI Central Building

Brain does amazingly efficient computation over big and complex information, while modern neuroscience itself often requires such computations for analyzing the data, to address mysteries of brain. To gain the insights for uncovering the superb neuro-computational principles and intelligence, the series of this mini-symposium is intended to discuss better computations and greater mathematical principles in a wider perspective, not only in theoretical neuroscience but also in machine learning and statistical-information sciences. This time, four eminent speakers will introduce us to cutting-edge works to face such challenges in their own disciplines. Who knows that these perspectives might be integral for future neuroscience?

13:30-13:35 Opening
13:35-14:20 Dr. Yoshimasa Tsuruoka (The University of Tokyo):
Recent Advances in Natural Language Processing and Game AI
14:20-15:05 Dr. Mahito Sugiyama (Osaka University):
Statistical Analysis on Order Structures
15:30-16:15 Dr. Makoto Yokoo (Kyushu University):
Market Design: Designing Social System by Game Theory
16:15-17:00 Dr. Tetsuya Ogata (Waseda University):
Deep Neural Models for Multimodal Integration in Robot System
17:00-17:45  Informal discussion (at Nakahara Lab/N201)

15th iTHES Colloquium
Date: March 17th (Thu.) 13:00-
"Modeling the transmission dynamics of Middle East respiratory syndrome (MERS) in the Repubic of Korea"
Prof. Hiroshi Nishiura (University of Tokyo)
Place: Nishina Hall (E02)


16th iTHES Colloquium
Date: April 19 (Tues.)
Time: TBA
"Exploring the world of microswimmers: a theoretical approach"
Dr. Kenta Ishimoto (RIMS, Kyoto Univ.)
Place: Okouchi Hall

Under the microscope, we can observe a large variety of swimming microbles rich in morphological and ecological diversity. The swimming is a vital concern for such primitive organisms to survive, and they appear to adapt to the environmental constraints of hydrodynamics at low Reynolds number. This can be highlighted by the scallop theorem, a
consequence of the symmetry in the equations of the system, where the inertia is negligible as in Aristotelean physics. In this talk, after a brief introduction to the hydrodynamics in the microworld, I will show how the theory works in the biological microswimmers such as bacteria, planktons and spermatozoa. Further examples will be provided in our recent studies on cell boundary accumulation phenomena and sperm guidance in mammalian fertilisation.

Paper of the week

A collaboration between Hitachi and iTHES researchers successfully explains recent data on Landau-Zener-Stueckelberg-Majorana interferometry observed ?in a semiconductor device.

J. Robert Johansson (former iTHES postdoc in Nori’s team and a visiting researcher from the Ukraine) and other iTHES members published a paper in collaboration with the experimentalists at Hitachi Cambridge Research Labs. Hitachi group had experimental data which could not be explained well by older models; thus, the iTHES RIKEN researchers came in and worked the theoretical aspects to explain the data. Some of the samples were made in France. The paper appeared in NanoLetters (link to http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b04356), a prestigious journal published by the American Chemical Society. It is an interdisciplinary journal publishing important works that concern the nano-scale in the wide areas of Chemistry, Materials, Physics, Devices. ?The abstract of the paper reads:
Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong- driving regime where we observe the emergence of Landau-Zener-Stu?ckelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ? 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology.

The paper can be found at ? http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b04356