This two-day workshop will bring together leading experts from academia, industry, and national laboratories to explore the rapidly evolving frontiers of quantum computing applications and their integration with high-performance computing (HPC) platforms.
Hosted by RIKEN Quantum, the event will provide a forum for discussing recent advances, practical challenges, and future directions toward achieving utility-scale quantum computations and robust quantum–HPC hybrid workflows.

The workshop is primarily an in-person event, but a special session on quantum computing in chemistry and life sciences will also be accessible via Zoom.

Inequality in resources is widely thought to undermine cooperation in social dilemmas. Yet cooperation among unequals is ubiquitous: between senior and junior colleagues, firms of different sizes, nations with asymmetric stakes. Here, we offer a resolution to this puzzle and derive a novel prediction: if the returns from cooperation are shared in accordance with the individuals' strategic incentives, inequality enables and strengthens cooperation. We develop a strategic framework to systematically explore cooperation when the returns of a joint project can be shared unevenly. We characterise the optimal sharing rule, which we call resilient sharing, that can sustain cooperation in repeated interactions when no other rule can. Resilient sharing equalises incentives to defect across players, but is neither egalitarian nor proportional. Surprisingly, it typically rewards weaker partners beyond their relative contributions. We show that cooperation can be sustained through direct reciprocity in any environment whenever individual contributions are sufficiently unequal. Evolutionary simulations and a behavioural experiment confirm the central prediction: under resilient sharing, cooperation succeeds among unequal partners where it fails among equals. This suggests that cooperation is more likely to evolve and thrive when individuals can vary contributions and divide returns flexibly, pointing to the role of institutions and norms in harnessing inequality to stabilize cooperation.

We analyse how inequality in endowments and social structure jointly affect individuals' ability to cooperate. Individuals repeatedly invest in a local public good ("cooperation'') in an environment that is described by a distribution of endowments and a network of beneficiaries. We measure the cooperativeness of an environment by the minimum discount factor needed to sustain (any) cooperation in equilibrium. We characterise the endowment distribution that maximises cooperativeness for any given network and the corresponding minimum discount factor. The latter is shown to be inversely proportional to the maximal index of the graph describing the network. The corresponding dominant eigenvalue of the adjacency matrix characterises the most cooperative income distribution. Moreover, we show that if an environment maximises cooperativeness (over all income distributions and networks of a certain size), then the network is described by a nested split graph. We further show that this is the same class of graphs that maximise welfare for any given discount factor, and yet, the most cooperative graph need not be equal to the most efficient.

I will present an overview of ongoing and future projects in our lab. We aim to understand how human genomes retain information about our evolutionary past; a central goal is to reconstruct a high-resolution history of humans, pushing the limits of what we can learn about our origins, past migrations, and adaptation to changing environments and survival pressures. Our genomes reveal events that would otherwise be lost to history, revealing how evolutionary forces have shaped genetic variation and influence our health today. How can we confidently infer events that occurred tens of thousands of years ago? I will discuss how converging and independent lines of genomic evidence can provide “rock-solid” support for major evolutionary events, including archaic admixture, large-scale migrations across continents, and population bottlenecks, and how we aim to extend these approaches to study the evolutionary history and origins of humans and other species.

Quantum link invariants relate topology in 3 dimensions to mathematical physics and representation theory. They admit liftings to 4-dimensional structures, known as link homology.

We will explain how the skein relations for quantum invariants turn into homological structures at this higher level and how semisimple representation theory turns into non-semisimple representations and homological algebra upon categorification.

Currently there are hundreds of models describing inflation, a period of accelerated expansion in our universe. Each model lead to different imprints in cosmological observables, and for the purpose of testing the idea of inflation itself, it is essential to understand which predictions are model independent. This lead to the idea of cosmological bootstrap, a set of constraints from physical principles and symmetries alone.
In this talk I will give an overview on the cosmological bootstrap program. I will first explain how locality, unitarity and symmetry can constrain the kinematics of cosmological correlators. I will then talk about some recent progress on constructing positivity bounds on cosmology, which places constraints on the interactions of fields in inflation.

Lecture I: Conventional approach: Repeatability, Heisenberg’s original uncertainty principle, and the SQL for gravitational-wave detection

The conventional approach to quantum measurement theory taken by von Neumann (1932), Dirac (1958), and Schrödinger (1935) assumes the "repeatability hypothesis" stating that if a physical quantity is measured twice in succession, then the same value is obtained each time, which is often quantitatively generalized to the "approximately repeatable hypothesis" stating that after a measurement of a physical quantity with error ε, the post-measurement deviation around the measured value is no larger than ε; this is equivalent to saying that the state after obtaining a measurement result with error ε becomes an ε-approximate eigenstate corresponding to that measurement result.

From the approximate repeatability hypothesis, one can derive "Heisenberg’s original formulation of the uncertainty principle," namely, that when position and momentum are approximately measured simultaneously, the product of their respective errors is at least ℏ/2 (Heisenberg 1927, Kennard 1927, Ozawa 2015), as well as the "standard quantum limit (SQL) for monitoring the free-mass position", which states that when the position of a free mass m is measured at a time interval τ, the result of the second measurement cannot be predicted with uncertainty smaller than (ℏτ/ m)^{1/2} (Caves 1985). The last result leads to a sensitivity limit for interferometric gravitational-wave detectors, and in the early 1980s it was therefore argued that gravitational waves of the expected strength could not be observed using interferometric detectors (Braginsky et al. 1980, Caves et al. 1980).

Biomolecular condensates are generally regarded as membrane-less organelles formed through liquid–liquid phase separation (LLPS). However, some condensates in living cells emerge in close proximity to biological membranes, where spatial confinement and surface geometry can critically influence their organization and function. In this talk, I will discuss recent advances in understanding how membrane association regulates the phase behavior of postsynaptic density (PSD) condensates. Using mesoscale molecular simulations constrained by experimental interaction data, our study reproduced the distinct condensate architectures observed in solution and on membranes. In three-dimensional solution, AMPA receptor/PSD-95 complexes form the condensate core, whereas NMDA receptor/CaMKII complexes localize to the shell. Strikingly, this organization becomes reversed in membrane-associated two-dimensional systems. The analysis revealed that this transition arises from the competition between CaMKII’s large excluded volume and its highly multivalent interactions. While excluded-volume effects dominate in solution, membrane confinement favors specific multivalent interactions, stabilizing distinct receptor nanodomains. These results provide a physical framework for understanding how spatial dimensionality and molecular architecture regulate biomolecular condensates and synaptic organization.

Real critical systems are often constrained by boundaries and affected by impurities. In 3d, the effect of disordered impurities on the boundary can be modeled by a random magnetic field on a two-dimensional defect. In this talk, I will discuss how such disorder affects the Wilson-Fisher fixed point in d=4−\epsilon dimensions. By analyzing the one-loop RG flow of the defect couplings using the replica formalism, we find a non-trivial "dirty" fixed point which represents a new boundary universality class, stabilized by the bulk \phi^4 interaction. Disordered systems at critical points are known to exhibit logarithmic behavior — I will also discuss how operator mixing in the replica limit gives rise to a logarithmic defect CFT in our setup.

In this talk, I will explore quantum-improved black hole solutions within the framework of asymptotic safety. In this approach, the Newton coupling becomes scale-dependent, necessitating a meaningful identification between the energy scale and a corresponding physical (length) scale to derive observable consequences for black hole spacetimes. I will argue that the requirement of consistency with the first law of black hole thermodynamics provides a physically motivated criterion for this scale-setting, particularly near the event horizon. Applying this principle, we propose a specific identification scheme that leads to a regularized geometry capable of resolving the ring singularity of Kerr black holes.

We study the quantum aspects of the conformal gravity in four dimensions, specifically addressing a known discrepancy in beta functions between general quadratic curvature theories and conformal gravity, which corresponds to two scalar degrees of freedom. We demonstrate that this mismatch is resolved by carefully introducing gauge-fixing and ghost terms via the BRST symmetry, which effectively adds the two scalar modes. Drawing lessons from two-dimensional quantum gravity and Liouville theory, we proceed to integrate the four-dimensional trace anomaly to derive a consistent Liouville action, which is given by a free-field action for the conformal mode with a consistent conformal anomaly. We give the condition that the BRST transformation is anomaly free. Finally I would like to talk about some application of this theory.

Lecture II: Modern approach: Quantum instruments, POVMs, measuring processes, intersubjectivity, and value reproducibility

The modern approach to quantum measurement theory is based on the "realizability theorem" stating that a measurement is physically realizable if and only if its statistical properties are represented by a completely positive instrument, and this is also equivalent to saying that the measurement can be described by an interaction with a measuring apparatus (Ozawa 1984, 2004).

The conventional analysis of a measuring process determines the post-measurement object state by applying the "projection postulate" to the meter measurement in the post-measurement state that "entangles" the object and the apparatus, but the above result has been established without assuming the projection postulate altogether; rather we use only the classical Bayesian probability update rule (Ozawa 1984).

We introduce the "intersubjectivity theorem" that states that, when multiple observers simultaneously and statistically correctly measure the same physical quantity, they obtain the same measurement value and the "value reproducibility theorem" that states that a statistically correct measurement correctly reproduces the value of the physical quantity immediately before the measurement (Ozawa 2025).

The above three theorems essentially solves the so-called measurement problem, since we eliminate the collapse of the wave function and we establish the reality of the the pre-measurement value of the measured observable to be copied to the meter value and to be recorded by the observer.

Lecture III: Measurement error, disturbance, the universally valid reformulation of Heisenberg’s uncertainty principle, and a quantitative generalization of the Wigner–Araki–Yanase theorem

Definitions of measurement error and disturbance are introduced (Ozawa 2002, 2019) and it is shown that there exists a solvable model for a physically realizable measurement that serves as a counterexample both to Heisenberg’s uncertainty principle in the conventional formulation and to the SQL (Ozawa 1988, 1989, 2002). Thus, those limits are no more considered as universal limits. In fact, the above counter example to SQL was found in 1988 using the idea of contractive state measurements by Yuen (1983) and the LIGO was started in 1994 to succeed in the gravitational wave detection in 2015 as announced in 2016.

New formulations are then proved for the uncertainty principle concerning the errors in the approximate simultaneous measurement of two physical quantities, called the "joint error relation" (Ozawa 2003b, 2004), and for the uncertainty principle concerning the error and disturbance associated with the measurement of a single physical quantity, called the "error-disturbance relation" (Ozawa 2003a). From the error-disturbance relation, a quantitative relation for measurement error under an additive conservation law is proved (Ozawa 2002a, 2003b), generalizing the "Wigner–Araki–Yanase theorem" (Wigner 1952, Araki-Yanase 1960), which states that a physical quantity not commuting with a conserved quantity cannot be measured accurately by a measurement interaction satisfying an additive conservation law. The above relation also derives limits for realizing quantum computing and operations under conservation laws (Ozawa 2002b), the results later developed as the resource theory of asymmetry.

We introduce a novel characterization of phase transitions based on hypothesis testing. In our formulation, a phase transition is defined as the breakdown of statistical indistinguishability under vanishing parameter perturbations in the thermodynamic limit. This perspective provides a general, order-parameter-free framework that does not rely on model-specific insights or learning procedures. We show that conventional approaches, such as those based on the Binder parameter, can be reinterpreted as special cases within this framework. As a concrete realization, we employ a distribution-free two-sample run test and demonstrate that the critical point of the two-dimensional Ising model is accurately identified without prior knowledge of the order parameter.

Lecture IV: Instruments in classical mechanics, quantum field theory, and cognitive science

In algebraic quantum field theory, measurements describable by interactions between the field and the measuring apparatus are characterized by the class of completely positive instruments that satisfy the condition called the normal extension property (NEP) (Okamura-Ozawa 2016).

In classical mechanics, traditionally only non-invasive measurements—those with trivial interaction—were considered admissible, for the observability of the trajectory of motion. Here, however, the full class of measurements realizable by classical-mechanical interactions is characterized in terms of instruments with NEP for the basis of the study of invasive measurements of classical systems.

Cognitive processes are also represented by completely positive instruments, along with the long-standing paradigm provided by von Helmholtz, who described a sensation-perception process as a sort of measuring interaction and referred to it as an unconscious inference. This framework is used to show the compatibility of the question order effect and the response replicability effect (Ozawa-Khrennikov 2019), which failed to be explained in an earlier approach using only projective measurement models. It is shown that there exists an instrument model, realizing both the question order effect and the response replicability effect, that is also capable of almost faithfully reproducing public-opinion survey data such as the well-known Clinton-Gore survey by Gallup in 1997 (Ozawa-Khrennikov 2021).

iTHEMS-UTokyo Intensive Lectures on Quantum Gravity
(10th Quantum Gravity Gatherings Lecture Series)

The 10th QGG Lecture Series is a special three-day installment of the intensive lecture series organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS. This celebratory edition will feature Professor Hikaru Kawai from Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), who will deliver a series of lectures on themes related to quantum gravity.

This lecture series will follow a style similar to Prof. Kawai's first QGG lectures, held three years ago at RIKEN (Wako) as the inaugural QGG event, which explored fundamental questions in quantum gravity, string theory, and the quantum universe. A distinctive feature of this 10th installment is that it will take place on the Komaba campus of The University of Tokyo, where one of the iTHEMS satellite offices is located. This will be the first QGG lecture series held outside Wako, with the aim of making the event more accessible to a broader group of participants.

Format:
Lectures will be given mainly in blackboard style and in English, encouraging active participation and in-depth Q&A discussions.
Poster sessions will also be held, giving participants an opportunity to present their own work or topics of interest. These sessions are intended to foster communication and stimulate the exchange of ideas among participants.

This event will take place in person only.

Target audience:
Senior scholars, early-career researchers, and students are all warmly welcome.

Registration deadline:
July 31, 2026