# Event Schedule

## Events for the 4th week of August 2021

2021-08-19

Monday, August 23, 16:00- Quantum Matter Seminar

Tuesday, August 24-25, RIKEN-Vancouver Joint Workshop on Quantum Computing

Friday, August 27, 12:30- Coffee Meeting

# Seminar Report

## Information Theory SG Seminar by Prof. Masayuki Ohzeki on August 4, 2021

2021-08-10

On August 4, Prof. Masayuki Ohzeki (Tohoku University/Tokyo Institute of Technology/Sigma-i Co., Ltd.) gave us a talk on the quantum annealing.

In the first part, after a general introduction, he demonstrated how to use the D-Wave machine from our personal computers.

It is remarkable that we can easily manipulate a number of quantum spins ourselves to solve an optimization problem.

In the second part, he reviewed working principles for quantum annealing: he started from the original proposal in 1998 and explained more recent methods such as the reverse annealing.

He also explained carefully the usefulness and the limits of the quantum annealing.

After discussing the theoretical perspective and how the machine is implemented using the superconducting qubits, he presented the application of the quantum annealer to the real world.

He showed his collaborations with many companies and how the quantum annealing can be used to solve real-life problems, such as the optimization of the evacuation routes or listing the hotel recommendation on the web.

A lot of interactive discussions were made during and after the talk. We really thank Prof. Ohzeki for his great talk.

Reported by Ryusuke Hamazaki

Quantum annealing and its fundamental aspects/ Quantum annealing and its application to real world

August 4 at 13:30 - 16:00, 2021

# Seminar Report

## iTHEMS Theoretical Physics Seminar by Dr. Shunichiro Kinoshita on August 16, 2021

2021-08-17

Shunichiro Kinoshita (Chuo U.) gave a talk on "Application of AdS/CFT to non-equilibrium phenomena in external electric fields. "After a brief introduction to the AdS/CFT correspondence, Shunichiro analyzed a holographic QCD system under strong electric fields constructed with D3/D7 branes. Shunichiro considered two kinds of electric-field configurations.The first one was a field with a sudden switching on (quenched setup). Shunichiro discussed how the confinement-deconfinement phase transition occurs and showed the possibility of deconfinement driven by turbulence. The second configuration was rotating electric fields. Shunichiro discussed how the frequency of the electric field affects the phase transition and argued the possibility of a novel state, distinct from the vacuum, for infinitesimally small electric fields with finite frequency.

Reported by Hidetoshi Taya

Application of AdS/CFT to non-equilibrium phenomena in external electric fields

August 16 at 13:00 - 15:00, 2021

# Announcement

## Agreement between RIKEN and Okinawa Institute of Science and Technology Graduate University on Cooperative Graduate School

2021-08-13

RIKEN and the Okinawa Institute of Science and Technology Graduate University (OIST) signed an agreement on August 1, 2021, for the purpose of promoting mutual research exchange and contributing to the promotion of science and technology. Under the cooperative graduate school system, RIKEN and OIST will deepen their collaboration in human resource development by accepting graduate students from OIST to provide research guidance and other services at RIKEN, and by having RIKEN researchers give lectures at OIST. The collaborative professors to be appointed for this system include Dr. Shigehiro Nagataki (Deputy Program Director, iTHEMS).

# Upcoming Events

## Seminar

### Application of Machine Learning on Many-Body Problems

August 23 at 16:00 - 17:15, 2021

Prof. Daw-Wei Wang (Professor, Department of Physics, National Tsinghua University, Taiwan)

Time: 4pm ~ 5:15pm (JST); 9am ~ 10:15am (CET); 3pm ~ 4:15pm (Taiwan)

In this talk, I will briefly introduce the application of machine learning methods on quantum many-body problems. It includes a self-supervised learning approach to decide the topological phase transition in the systems of ultracold atoms by using Time-of-Flight images only without knowing any priori knowledge [1]. We then develop the Random Sampling Neural Networks for the investigation of quantum many body ground state properties in the strong interacting regime by a model rtained in the weak interacting regime [2]. Finally, we provide an Quantum-Inspired-Recurrent Neural Network, which could give a precise long-time dynamics of a quantum many-body system, even the model is trained in the short-time regime. We hope to show the great possibility to use machine learning as a new tool to investigate the quantum many-body problems.

*Detailed information about the seminar refer to the email.

Venue: via Zoom

Event Official Language: English

## Workshop

### RIKEN-Vancouver Joint Workshop on Quantum Computing

August 24 - 25, 2021

The main aim of this workshop is that the quantum people in RIKEN (iTHEMS and RQC) and Vancouver (Quantum BC) get together online to discuss scientific activities and explore future collaborations.

Program:

August 24, 2021 (8:30am - 1:00pm) Tokyo

August 23, 2021 (4:30pm - 9:00pm) Vancouver

Tetsuo Hatsuda (iTHEMS): Welcome + iTHEMS overview

Yasunobu Nakamura (RQC): RQC overview

Lukas Chrostowski (UBC): Quantum BC overview

Shunji Matsuura (1QBit): Accurate state preparation on noisy quantum devices

Olivia Di Matteo (UBC): Operational, gauge-free quantum tomography

Yasunobu Nakamura (RQC): Towards superconducting quantum computing

Jason Chang (iTHEMS): Improving Schroedinger equation implementations with gray code for adiabatic quantum computers

Robert Raussendorf (UBC): Computationally universal phase of quantum matter

Akira Furusawa (RQC): Large-scale quantum computing with quantum teleportation

August 25, 2021 (8:30am - 1:30pm) Tokyo

August 24, 2021 (4:30pm - 9:30am) Vancouver

Etsuko Itou (iTHEMS): Digital quantum simulation for screening and confinement in gauge theory with a topological term

Joe Salfi (UBC): Engineering long coherence times of spin-orbit qubits in silicon

Seiji Yunoki (RQC): Quantum simulations for quantum many-body systems: Variational quantum algorithms and beyond

Takumi Doi (iTHEMS): Hybrid quantum annealing via molecular dynamics

Drew Potter (UBC): Simulating highly-entangled matter with quantum tensor networks

Seigo Tarucha (RQC): High-fidelity quantum gates in silicon quantum computing

Organizing Institutes:

iTHEMS: RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program

RQC: RIKEN Center for Quantum Computing

Quantum BC

Organizers:

Tetsuo Hatsuda (iTHEMS)

Yasunobu Nakamura (RQC)

Shunji Matsuura (1QBit)

Joseph Salfi (UBC)

Erika Kawakami (RQC / RIKEN CPR)

Neill Lambert (RIKEN CPR)

Venue: via Zoom

Event Official Language: English

## Seminar

### Towards a description of amorphous solids and viscoelastic materials using effective field theory and holographic methods

September 10 at 13:30 - 15:00, 2021

Prof. Matteo Baggioli (Associate Professor, School of Physics and Astronomy, Shanghai Jiao Tong University, China)

Among the most ubiquitous phases of matter, gases and crystalline solids are definitely the simplest to be described. Their physics is indeed almost entirely textbooks material and it can be summarized within the elegant frameworks of kinetic theory and Debye theory. Liquids and specially viscoelastic systems and amorphous materials (e.g. glasses) exhibit a much richer and complex dynamics with provides a large set of fundamental and unresolved physical questions. Given the tremendous microscopic complexity of these systems, which is manifest in a large landscape of scales and anomalous behaviours, the effective field theory (EFT) paradigm of isolating only a few, but fundamental, information could provide a winning approach. This talk is based on the simple, but indeed extremely difficult, question of whether these phases of matter can be distinguished, classified and understood using emergent and/or fundamental symmetry principles as in their ordered crystal counterpart. More precisely, we will combine EFTs, hydrodynamics and holographic methods to tackle the above question. I will present the most recent developments in this direction and I will discuss with you the most important open questions and avenues to explore in the near future.

Venue: via Zoom

Event Official Language: English

## Colloquium

### Finding Gravitational Waves from the Early Universe

September 27 at 16:00 - 17:30, 2021

Prof. Eiichiro Komatsu (Director, Max Planck Institute for Astrophysics, Germany)

The Cosmic Microwave Background (CMB) gives a photographic image of the Universe when it was still an “infant”. We have been using it to test our ideas about the origin of the Universe. The CMB research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations in the period of the early Universe called cosmic inflation. While we have accumulated strong evidence for this picture, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe physics of gravitational waves from inflation, and the LiteBIRD proposal.

Venue: via Zoom

Event Official Language: English

# Paper of the Week

## Week 4, August 2021

2021-08-19

Title: Observing Supernova Neutrino Light Curves with Super-Kamiokande: II. Impact of the Nuclear Equation of State

Author: Ken'ichiro Nakazato, Fumi Nakanishi, Masayuki Harada, Yusuke Koshio, Yudai Suwa, Kohsuke Sumiyoshi, Akira Harada, Masamitsu Mori, Roger A. Wendell

arXiv: http://arxiv.org/abs/2108.03009v1

Title: The generalized Nielsen-Ninomiya Theorem for the 17 wallpaper: Classification of 2D nodal superconductors, Dirac semimetals, and non-Hermitian nodal systems

Author: Congcong Le, Zhesen Yang, Fan Cui, A. P. Schnyder, Ching-Kai Chiu

arXiv: http://arxiv.org/abs/2108.04534v1

Title: Matrix Model simulations using Quantum Computing, Deep Learning, and Lattice Monte Carlo

Author: Enrico Rinaldi, Xizhi Han, Mohammad Hassan, Yuan Feng, Franco Nori, Michael McGuigan, Masanori Hanada

arXiv: http://arxiv.org/abs/2108.02942v1

Title: Universality of Interior Metric of Typical Black Holes

Author: Hikaru Kawai, Yuki Yokokura

arXiv: http://arxiv.org/abs/2108.02242v2

Title: Stability of the protoneutron stars toward black hole formation

Author: Hajime Sotani, Kohsuke Sumiyoshi

arXiv: http://arxiv.org/abs/2108.02484v1

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