Wave–particle complementarity is one of the central principles of quantum mechanics, traditionally quantified through the Englert–Greenberger–Yasin relation between which-way information and interference visibility. In higher-dimensional and resource-theoretic settings, however, visibility is no longer unique, and it becomes natural to reformulate complementarity in terms of basis-dependent predictability, coherence, and mixedness.

In this talk, I present two related works along this line. First, I discuss an exact complementarity relation between classical definiteness and quantumness, where definiteness is defined operationally through the resilience of a quantum state under nonselective dichotomic yes/no measurements, while the complementary quantum contribution is quantified using a Kirkwood–Dirac-based notion of coherence/interference motivated by recent KD-based coherence measures. Second, I introduce a geometric predictability defined by the Bures distance between the dephased state and the maximally mixed state. This predictability depends only on the observed measurement statistics and admits a closed form in terms of the Bhattacharyya overlap. For pure states, it satisfies an exact complementarity relation with nonclassical Kirkwood–Dirac coherence; for mixed states, this motivates a convex-roof extension whose operational meaning is the classically irreducible part of measurement randomness, with implications for guessing probability and min-entropy. Finally, motivated by the decomposition of entropy production into population and coherence contributions in quantum thermodynamics, and by standard wave–particle–mixedness triality relations, I show how the usual predictability–coherence duality can be promoted into a triality relation involving predictability, coherence, and mixedness.

Altogether, the talk connects wave–particle duality, coherence resource theories, operational guessing tasks, and thermodynamic balance relations within a unified framework.

We will hold an annual in-house gathering, “iTHEMS NOW & NEXT,” for FY 2026.
The event provides a great opportunity for all iTHEMS members, including visiting researchers and, in particular, new arrivals, to gain a comprehensive overview of iTHEMS’s current activities and future directions.

The detailed program will be announced in due course, but there will be poster sessions for all members, so please be ready to present one.

Imagine that you are in a room with no information about time. The room is located in a cave, where temperature and light intensity remain constant. In such an environment, would you be able to wake up tomorrow or the day after?
In fact, most humans can wake up at roughly similar times on successive days. This is because we possess internal daily rhythms, known as circadian rhythms. Biological experiments have shown that such rhythms are not unique to humans, but are shared by many species on Earth.
In this talk, I will introduce some open problems related to these daily rhythms, and discuss approaches based on dynamical systems theory and the renormalization group method, from the perspectives of applied mathematics and theoretical physics.

13:45 Opening

14:00-14:05 Introduction
Atsushi Iriki (Teikyo University Advanced Comprehensive Research Organization Division of Artificial Intelligence, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

14:05-14:35 "Interpretation of Life Phenomena Using Quantum Wave Functions and Field Theory"
Kazuhiro Sakurada (Keio University Medical School and RIKEN Center for Integrative Medical Sciences (IMS), Predictive Medicine Special Project (PMSP))

14:35-14:45 Q&A

14:45-15:30 "Bridging neurophysiology and quantum-like cognition"
Andrei Khrennikov (Center for Mathematical Modeling in Physics and Cognitive Sciences Linnaeus University)

15:30-15:45 Q&A

15:45-16:00 "Quantum-Like Measurement"
Masanao Ozawa (RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS), RIKEN TRIP FQSP, and Nagoya University)

16:00-16:05 Closing Remarks
Satoshi Iso (Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

Host Laboratory: Predictive Medicine Special Project, RIKEN Center for Integrative Medical Sciences (IMS) / RIKEN Center for Interdisciplinary Theoretical and Mathematical Science (iTHEMS)

*Registration is required by April 14 via the registration form.
Contact: Predictive Medicine Special Project (pmsp-web@ml.riken.jp)

This is a joint seminar with Institute for Physics of Intelligence (iπ), UTokyo

Anomaly detection relaxes the assumptions of how new physics should look and extends the reach of what we can discover. However, interpreting the data and estimating backgrounds remains a challenge. In this new work, we investigate anomalous events selected by the OmniLearned Foundation model across different model sizes, performing a full analysis using CMS Open Data. Surprisingly, models of different sizes, trained on the same data with the same loss functions, select entirely different collisions. In particular, the large OmniLearned model (500M parameters) selects events that are not well described by our background model.

This is a TJR-iTHEMS Joint Seminar supported by ASPIRE Program

ABSTRACT
Neutron stars were first posited in the early thirties, and discovered as pulsars in the late sixties; however we are only recently beginning to understand the matter they contain. I will describe the ongoing development of a consistent picture of the liquid interiors of neutron stars, now driven by ever increasing observations as well as theoretical advances. These include observations of heavy neutron stars of about 2.0 solar masses and higher; ongoing inferences of masses and radii by the NICER telescope; and observations of binary neutron star mergers, through gravitational waves as well as across the electromagnetic spectrum. Theoretically an understanding is emerging in QCD of how nuclear matter can turn into deconfined quark matter, which I will illustrate with modern quark-hadron crossover equations of state.

BRIEF BIO
Gordon Baym is a Professor of Physics at the University of Illinois. Educated at Cornell and Harvard, he spent two years at the Niels Bohr Institute. His interests range from matter under extreme conditions to ultracold atomic physics, astrophysics, and nuclear physics. A pioneer in the study of pulsars and neutron stars, he is a member of the U.S. National Academy of Sciences and received the APS Medal for Exceptional Achievement in Research, the Hans Bethe and Lars Onsager Prizes, and the Eugene Feenberg Memorial Medal.

This is the self-introduction talk by Pradyot Pritam Sahoo. Pradyot is a Student Trainee in iTHEMS.

Groups need to make decisions, and there are a wide variety of ways this can be done, each maximizing different notions of fairness. Social Choice Theory provides a mathematical framework to investigate these possibilities rigorously. Infamous for its many impossibility results, this topic reveals some fundamental limits to democracy. Beyond this, we'll discuss potential resolutions to these problems, as well as their real world implications.

Mathematical Application Research Team is honored to invite Prof. Shin-ichi Ohta from the University of Osaka to this meeting. Everyone is welcome to join the meeting to listen to his seminar.

Title: Synthetic and comparison Lorentzian geometry

Abstract: In this talk we review recent developments of synthetic geometric approaches to Lorentzian geometry, motivated by the theory of less regular spacetimes in general relativity as well as comparison geometry in the Riemannian setting. Among others, optimal transport theory plays a vital role.

One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks.

While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form.
The registration deadline is May 7 (Thu).
Please note that the registration form is the same for all three days, so you only need to register once.

The 1st day: May 11 (Mon)
13:30-15:00 Lecture 1
15:00-15:30 Coffee break
15:30-17:00 Lecture 2

This event is in-person only.

One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks.

While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form.
The registration deadline is May 7 (Thu).
Please note that the registration form is the same for all three days, so you only need to register once.

The 2nd day: May 12 (Tue)
9:00–10:30 Lecture 3
10:30–11:00 Coffee break
11:00–12:30 Lecture 4
12:30-13:30 Lunch time
13:30-15:00 Lecture 5
15:00-15:30 Coffee break
15:30-17:00 Lecture 6

This event is in-person only.

A doubly stochastic matrix is unistochastic if its entries correspond to the squared moduli of a unitary matrix. Determining which n × n doubly stochastic matrices admit such a representation remains an open problem at the intersection of convex geometry, combinatorics, and quantum information. For 3 × 3 matrices, elegant triangle inequalities provide a complete characterization: the unistochastic set occupies approximately 75% of the Birkhoff polytope and exhibits deltoid cross-sections. For n ≥ 4, the characterization problem remains unresolved and is influenced in unexpected ways by the prime factorization of n via the defect of the Fourier matrix. This presentation surveys these results and then establishes a connection to a second, seemingly unrelated question: given a tripartite quantum state with small conditional mutual information, to what extent can one subsystem be recovered from the others? The Petz recovery map and its rotated variants offer a universal solution. These two topics are linked through coherification, which concerns when a classical stochastic process can be elevated to coherent quantum dynamics, and through the conditional mutual information as a continuous measure of non-unistochasticity. The talk concludes with open problems at this interface, including the star-shapedness conjecture for n = 4 and the pursuit of tighter recovery bounds.

One of the central goals of quantum information theory is to quantitatively clarify the relationship between the performance of quantum information processing and the valuable quantum features that underlie it. In this lecture, we will discuss quantum resource theories, a framework that provides a useful approach to this question. By presenting concrete examples—starting with entanglement theory, the most representative resource theory—as well as recent research results, we will see how perspectives and tools from information theory enable the quantification of quantum resources and the characterization of their convertibility. Beyond entanglement theory, we plan to discuss other key settings such as quantum thermodynamics, resource theory of asymmetry, and quantum magic—relevant resource in fault-tolerant quantum compuation. The overall aim of this lecture is to provide new analytical viewpoints that can be applied to a wide range of systems and quantum information processing tasks.

While we do not plan to change the overall start and end times for each day, the detailed lecture schedule is subject to change. The intensive course will be held over three days. Please register for the course using the form.
The registration deadline is May 7 (Thu).
Please note that the registration form is the same for all three days, so you only need to register once.

The 3rd day: May 15 (Fri)
9:00–10:30 Lecture 7
10:30–11:00 Coffee break
11:00–12:30 Lecture 8
12:30-13:30 Lunch time
13:30-15:00 Free discussion/Summary of the lectures
15:00-15:30 Coffee break
15:30-17:00 Lecture 9/Seminar

This event is in-person only.

Singularities are locations where something is exceptional. In particular, singularities of differentiable maps are mathematical concepts corresponding to stationary points of functions and apparent contours of surfaces under projection onto the retina. These are unavoidable in general, but important to study the shape of spaces and behavior of maps. The theory for them was initiated by R. Thom in 1950's, and have been deeply studied by many researchers.