Members

Staff Scientist

Aidan Chatwin-Davies

2018 Ph.D. California Institute of Technology
2013 M.Math. University of Waterloo
2011 B.Math. University of Waterloo

My research interests lie in quantum information science and quantum gravity, and I generally work on problems in which these fields intersect. I'm particularly interested in cosmology, and a good part of my current research explores what lessons information science can bring to cosmology, and vice versa.

私の研究テーマは量子情報科学と量子重力であり、これらの分野が交差する問題に取り組んでいます。特に宇宙論に興味があり、情報科学が宇宙論にどのような教訓をもたらすか(またその逆も)を主に探求しています。

List of publications: https://orcid.org/0000-0003-1406-9271

Email: aidan.chatwin [at] oist.jp

Post-doctoral Scholars

Stefan Eccles

2021 Ph.D. University of Texas at Austin

2011 B.S. Montana State University

Much of classical and quantum physics takes for granted the existence of a background spacetime which provides the stage on which dynamics unfold. General relativity improves this situation by treating the spacetime as a smooth Lorentzian manifold which interacts dynamically with matter and energy. But the modern perspective is that this level of description is not the deepest, and that spacetime itself emerges from more fundamental quantum degrees of freedom. I’m interested in understanding how causal and metric structure can emerge from such a description, using hints from the field of spacetime thermodynamics and the tools of quantum information theory and quantum many-body physics. I am interested in gleaning lessons from the relatively well-understood context of AdS/CFT and applying them to spacetime emergence more generally, and particularly to the ill-understood context of positive cosmological constant.

List of publications: https://arxiv.org/search/?searchtype=author&query=Eccles%2C+S

Email: stefan.eccles [at] oist.jp

Goncalo Araujo Regado

2023 Ph.D. University of Cambridge

2019 M.Math. University of Cambridge

2018 B.A. University of Cambridge

My work focuses on finding a non-perturbative theory of quantum gravity. Given the lack of experimental observations of quantum gravitational effects to guide us in theoretical model-building, we have to resort to more fundamental principles which we believe to be true and to the consistency between them. The past several decades of research hint strongly at the fact that quantum gravity is an intrinsically holographic theory. This is a statement about how information is encoded in a quantum gravitational system and it posits that this is done via some (non-gravitational) quantum mechanical degrees of freedom living at the boundary of the system. In my work I explore this idea and its far-reaching consequences. This is a two-way street: on the one hand we can use known facts about gravity (in the semiclassical limit) to try to constrain the sort of holographic models that could be suitable candidates to define quantum gravity; on the other, we can use our knowledge of these dual quantum mechanical systems to try to infer properties of gravitational systems in the quantum regime.

Publications: https://inspirehep.net/authors/2061607

Email: goncalo.araujo [at] oist.jp

Francesco Sartini

2022 Ph.D. ENS de Lyon, France

2019 M.Sc. ENS de Lyon, France

2017 B.Sc. University of Florence, Italy

Quantum field theory and general relativity describe two completely different worlds. In the former, the spacetime is fixed, while matter is made of discrete quanta. In general relativity everything is smooth, but there is a dynamical interaction between spacetime and energy through the gravitational field.

The modern point of view on this contradiction is that spacetime itself should be made of fundamental quanta, the gravitational interaction emerging through the exchange of information at a microscopic scale. This expectation is based on the important interplay between observers, measurement and entropy in quantum mechanics and the relationship between symmetries, boundaries, reference frames and observers in general relativity and gauge theories.

In particular, I aim to explore how this point of view applies to specific physical systems like black holes or when considering the whole Universe in its average cosmological properties.

List of publications: https://inspirehep.net/authors/1841011

Email: francesco.sartini [at] oist.jp

Markus Frembs

2020 Ph.D. Imperial College London, United Kingdom

2015 M.Sc. University of Erlangen-Nuremberg, Germany

2013 B.Sc. University of Erlangen-Nuremberg, Germany

While classical physics has a distinctively geometric character, and geometry even becomes dynamical in general relativity, quantum theory is by and large an algebraic formalism. The difficulty in formulating a theory of quantum gravity may thus be seen as rooted in the fact that quantum theory is irrevocably non-classical, in the sense that it escapes a geometric description.

My work aims at better demarcating classical and quantum theory. In particular, I am interested in two aspects of this divide. On the one hand, a quantitative characterisation of non-classicality understood as a resource is necessary in order to design algorithms for future quantum computers and to achieve provable quantum advantage. On the other hand, non-classicality understood as a geometric obstruction might prove crucial in departing from classical concepts inherent to general relativity and differential geometry.

List of publications: https://orcid.org/0000-0001-6653-4652

Email: markus.frembs [at] oist.jp

Visiting Researcher

Bilyana Tomova

2024 Ph.D. University of Cambridge

2019 MASt. University of Cambridge

2018 B.Sc. Sorbonne University

My work focuses on studying symmetries of gravity and other gauge theories (forces that mediate interactions). Symmetries lead to conservation laws, that are the origin of interesting phenomena on both classical and quantum levels. Therefore, the theoretical understanding of the symmetries of a given theory can help us design experiments that test the validity of our current models.

Currently, with other members of the Qubits and Spacetime Unit, I am working on understanding the structure and symmetries of a theory that describes only a subregion of the universe (as opposed to the entire universe, which is the usual setup). This has the potential to reveal bits of answers to some of the most fundamental questions such as “What makes our clocks tick?” and “What is the experience of an observer in a quantum universe?”.

List of publications: https://inspirehep.net/authors/2018477?ui-citation-summary=true&ui-exclude-self-citations=true

Email: bilyana.tomova [at] oist.jp

Ph.D. Students

Julian De Vuyst

2021 MSc Ghent University
2019 BSc Ghent University

Email: julian.devuyst [at] oist.jp

Research Unit Administrator

Midori Tanahara

Midori was born and raised in Okinawa, studied in Tokyo/Vancouver and joined OIST in 2008. She provides administrative support to the Hoehn Group for the day-to-day running of the laboratory. Outside of work, she enjoys travelling, swimming and cooking.

Email: midori.tanahara [at] oist.jp

Alumni

Post-docs

Isha Kotecha

2020 PhD Max Planck Institute for Gravitational Physics-Potsdam, Humboldt University of Berlin

2013 MASt University of Cambridge

2012 MSci (incl. BSc) Imperial College London

To understand better the nature of spacetime and quantum theory is an ongoing effort across communities. The interface of gravity, thermal physics and quantum theory has offered many key insights in this respect. For instance, the notions of time, temperature and energy are found to be intimately linked, especially in a background independent context. These further seem to be related to the presence of information barriers in general, e.g. causal horizons in spacetime. There are several such concepts and quantities that become deeply intertwined at this interface, like time, energy, entropy, geometry, causality, entanglement and observers. My research interests are broadly aimed at probing this interface, utilising tools from quantum information theory and many-body physics. I am particularly interested in understanding generic, more universal properties of (quantum) spacetime, and its thermal features. I am also interested in spacetime thermodynamics, and its emergence from the collective behaviour of underlying quantum gravitational degrees of freedom.

List of publications: https://arxiv.org/search/?query=Isha+Kotecha&searchtype=all

Josh Kirklin

2020 Ph.D. University of Cambridge

2016 M.Ma. University of Cambridge

2016 B.A. University of Cambridge

At a very basic level, scientific observation is just a process by which we are provided with a list of numbers describing the outcomes of some experiments. Scientists attempt to find a mathematical model which can reproduce correlations between the various numbers in the list, but arguably the list, and the information it contains, is more fundamental than the model. This perspective was termed 'it from bit' by John Wheeler in 1986, and my main interests lie in applying it to quantum gravity. In particular, I try to think about how this approach is informed by experimentally verified properties of gravity, such as its low energy behavior in the semiclassical limit. The relevance of objects such as black holes in this regime allow us to ask very sharp questions about the underlying information. More generally I am also interested in what we can learn from specific models that describe the ultraviolet physics.

List of publications: https://inspirehep.net/authors/1658025

Website: http://kirklin.science

Fabio Maria Mele

2020 Ph.D. University of Regensburg, Germany

2016 M.Sc. University of Naples “Federico II”, Italy
2013 B.Sc. University of Naples “Federico II”, Italy

Recent developments in different approaches to quantum gravity seem to suggest a very intriguing picture of spacetime as a many-body quantum system whose physical properties result from the correlations and exchange of information among its microscopic texture. My main interests lie in further exploring such a picture and its foundational implications, with a multi-disciplinary and possibly approach-independent attitude. This consists first of all in investigating how the structures characterizing spacetime at classical and ultimately quantum level can be inferred from general ideas and techniques borrowed from statistical mechanics, information theory and thermodynamics. Second, I am interested in the lessons and insights that we can learn from implementing the above perspective in specific microscopic models of spacetime. In this sense, black holes and cosmological systems can offer promising scenarios where these questions can be addressed in a simplified setting.

List of publications: https://arxiv.org/search/?searchtype=author&query=Mele%2C+F+M

Rotation Students

Jiahui Bao

AY 2020 Term 2: Jan-Apr, 2021

Master degree: Sun Yat-sen University

Bachelor degree: Hunan University

Miguel Jorquera Riera

AY 2020 Term 2: Jan-Apr, 2021

2018 MPhys (incl. BSc), Lancaster University

Snigdh Sabharwal

FY2020 Term 3: May-Aug 2021

Bachelor degree: University of Delhi

Master degree: Leiden University

Tatiana Iakovleva

AY2021 Term 1: Sept-Dec, 2021

Bachelor degree: Novosibirsk State University

Master degree: Novosibirsk State University

Joshua Carlo Casapao

AY2021 Term 1: Sept-Dec, 2021

Julian De Vuyst

AY2021 Term 2: Jan-April 2022

2021 MSc Ghent University
2019 BSc Ghent University

Andreani Petrou

AY2021 Term 2: Jan-April 2022

2014-2017 Bachelor in physics, Leiden University (Netherlands)

2018-2019 MSc in mathematical physics, University of Edinburgh (UK)

Julian Lang

AY2022 Term 1: Sept-Dec 2022

Saswato Sen

AY2022 Term 1: Sept-Dec 2022

Javier Pagan Lacambra

AY2023 Term 1: Sept-Dec 2023

I completed my Masters in Mathematics and Physics by the University of Manchester in 2022, where I specialized in Differential Geometry, Gauge Theories and General Relativity. From last October to March, I was working in Prof David Elkouss’s unit – studying several optimizations of Shor’s Quantum Factoring Algorithm applied to RSA integers. In doing so, I had the chance to explore different areas of Quantum Information Theory, like Error Correction and Quantum Networks. During this rotation, I would like to explore the connection between Information Theory and the emergence of Quantum Mechanics, Spacetime and Gravity.

Email: j.pagan [at] oist.jp