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Yukinao Akamatsu03/08/2026, 09:00
Open quantum systems provide a framework to describe quantum systems interacting with their environments. The theory has been developed mainly in quantum optics and has recently found applications in various areas of physics, including condensed-matter physics, quantum information, high-energy physics, and cosmology. In this lecture, I will give an introduction to the theory of open quantum...
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Sarah Shandera03/08/2026, 11:30
Observers, unlike experimentalists, have no control over the autonomously evolving quantum systems they study. They infer dynamics and states from partial observations, limited to spatial subsystems, finite time windows, accessible charges, and finite measurement resolution. This talk will discuss features revealed by analytic and numerical examples of closed systems described as ensembles of...
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Cliff Burgess03/08/2026, 13:30
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Fumiya Sano03/08/2026, 14:30
Admitting the inflationary scenario in the primordial universe, the cosmological structure today originated from quantum fluctuations during cosmic inflation. Since the dynamics of curvature perturbations after inflation is well described by classical equations of motion, there should have been a quantum-to-classical transition in the history of the universe. This classicalization process has...
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Amaury Micheli03/08/2026, 15:30
The statistical properties of the CMB anisotropies, reflecting the curvature inhomogeneities in the early Universe, are very well accounted for by assuming that they emerged from amplified vacuum fluctuations. Being the result of a genuine quantum process, it is natural to wonder which properties of these primordial inhomogeneities are quantum, and which, if any, persisted until their...
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Yi Wang03/08/2026, 16:30
Over the past few months, AI and AI agents have fundamentally shifted research methodologies in theoretical physics. This talk is divided into two parts. First, we provide an overview and real-world examples of AI integration in daily research, ranging from "vibe physics" via chat interfaces to systematic agent-assisted-research using Codex and Claude Code. Second, we introduce our...
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Prof. Andrew Tolley (Imperial, London)04/08/2026, 09:00
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Yannis Georis (Kavli IPMU)04/08/2026, 11:30
The effective number of neutrinos, Neff, is a key parameter in the standard Lambda-CDM cosmology, which captures how many light degrees of freedom are in the early universe plasma before Big Bang Nucleosynthesis. It is therefore a crucial probe of light and feebly interacting hidden sectors. In this talk, I will review how one can describe the evolution of neutrinos in the early universe using...
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Andrew Tolley04/08/2026, 13:30
Schwinger’s Closed Time Path formalism is the basis of modern treatments of cosmological field theories, hydrodynamics and open quantum systems. Its application to gauge theories at finite temperature is well studied, relying on KMS boundary conditions and complex-time contours. By contrast the discussion of gauge theories such as Yang-Mills out of equilibrium has been less well developed, in...
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Kanji Nishii04/08/2026, 14:30
This talk presents a bottom-up open effective field theory (EFT) for non-Abelian gauge theories within the Schwinger-Keldysh formalism. Instead of integrating out the environment completely and starting from a nonlocal influence functional, we retain slow environmental response variables and construct a local system-environment EFT. The environmental sector, described by dynamical color-frame...
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Toshifumi Noumi04/08/2026, 15:30
I will begin by reviewing the motivation for developing open-system effective field theories for cosmology and gravity. I will then discuss how dynamical gravity can be consistently incorporated into the Schwinger–Keldysh EFT framework for systems with local dissipation, emphasizing the role of collective modes that encode fluctuations in the environmental sector. Finally, I will discuss...
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Lucas Vicente García-Consuegra04/08/2026, 16:30
De Sitter spacetime describes both the earliest and latest stages of our Universe, but its lack of time-translation symmetry means that many of the standard tools of quantum field theory do not directly apply. In this talk, I will introduce the in-in formalism as a framework for studying quantum fields in this setting and use it to investigate a stochastic version of the Schwinger effect....
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Yuto Ashida04/08/2026, 17:30
Recent advances in programmable quantum systems have made it possible to monitor and control many-body states at the single-quantum level. In this talk, I shall discuss how quantum measurements open new frontiers at the interface of many-body physics and quantum information. I will first introduce how measurement backaction leads to intriguing many-body phenomena in open systems, such as...
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Jason Pollack05/08/2026, 09:00
Quantum information theorists, many-body physicists, and cosmologists often have very different intuitions about open systems. In particular, the first group usually consider all possible quantum physical evolutions compatible with unitarity, while the latter groups usually prefer to derive open-system behavior by integrating out a specific, often infinite, environment sector. I'll give a...
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Hajime Fukuda (Kavli IPMU)05/08/2026, 10:00
Quantum sensing provides powerful advantages over classical measurement techniques for detecting extremely weak signals, such as those induced by dark matter. By exploiting genuinely quantum resources, including entanglement and superposition, quantum sensors can achieve enhanced sensitivity and precision. In this talk, I will review basic applications of quantum sensing to dark matter...
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Takahiro Tanaka05/08/2026, 11:30
We will summarise how it is difficult to detect the quantum nature, especially squeezed nature, of gravitational waves.
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Kai Schmitz (Kavli IPMU, University of Tokyo)05/08/2026, 13:30
I will review the 2023 pulsar timing array (PTA) evidence for a stochastic gravitational-wave background at nanohertz frequencies and discuss how PTA observations allow us to search for new particle and gravitational physics, including: (1) physics beyond the Standard Model in the early Universe, (2) dark matter in our galaxy and in the vicinity of supermassive black-hole binaries, and (3)...
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Ripalta Amoruso05/08/2026, 14:30
The work describes gravitational wave propagation through a stochastic distribution of weak gravitational lenses beyond the geometric optics limit. The lens distribution is modeled as a static random background field and we formulate the problem in the language of quenched disorder, treating the disorder averaged densitymatrix as the fundamental object from which observables are computed....
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Cliff Burgess05/08/2026, 15:30
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Jiro Soda05/08/2026, 16:30
The quest for the graviton—the hypothetical quantum of gravity—remains one of the ultimate frontiers in modern physics. In this talk, I will first introduce Freeman Dyson’s seminal work on graviton detection. Although Dyson famously reached a negative conclusion, arguing that detecting a single graviton is practically impossible, a closer look at his arguments reveals invaluable hints for...
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Masaru Hongo06/08/2026, 09:00
Hydrodynamics provides a universal description of the long-wavelength and low-frequency real-time dynamics of many-body systems near local thermal equilibrium. While its traditional formulation is based on conservation laws, thermodynamics, and a derivative expansion of constitutive relations, recent developments have revealed a unified field-theoretical framework underlying both deterministic...
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Yi Yin06/08/2026, 11:30
Understanding thermalization in quantum field theory stems largely from understanding properties of non-hydrodynamic excitations. These nonhydrodynamic excitations are known to differ structurally between weakly and strongly coupled theories. In this talk, I demonstrate that a large class of non-hydrodynamic excitations can be understood as a consequence of different realizations of a symmetry...
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Atsuhisa Ota06/08/2026, 13:30
In this talk we discuss the mode structure of general U(1)-charged first-order relativistic hydrodynamics, formulated within an effective field theory for dissipative fluids in flat Minkowski spacetime. Although first order relativistic hydrodynamics is known to be illposed as a system of partial differential equations, we argue that this conclusion is potentially misleading because...
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Hongchao Li06/08/2026, 14:30
Superfluidity encompasses a variety of remarkable physical phenomena, including zero viscosity in transport, nucleation of quantized vortices, and nonclassical rotational inertia. Recent advances in ultracold-atom experimental techniques have enabled unprecedented control over superfluids in quantum systems, such as bosonic superfluidity in interacting Bose-Einstein condensate (BEC) and...
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Shivam K. Sharma06/08/2026, 15:30
Open quantum systems provide the natural setting for describing fluctuations, dissipation, and non-equilibrium dynamics. While these phenomena are well understood for weakly coupled baths, strongly coupled baths remain difficult to treat using conventional methods. In this talk, I will discuss how recent developments in real-time holography (a real-time formulation of the AdS/CFT...
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Hitoshi Murayama (Kavli IPMU)06/08/2026, 16:30
I discuss exact solutions to two- and four-dimensional gauge theories and their generalized symmetries.
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Genki Yoshimura06/08/2026, 17:30
Symmetry provides a unifying framework for understanding physical phenomena. Recent developments have broadened this framework to include higher-form symmetry. From this viewpoint, photons can be understood as Nambu–Goldstone modes associated with spontaneously broken higher-form symmetries. So far, however, higher-form symmetry has been discussed mainly in zero-temperature and equilibrium...
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Luca Marchetti (Kavli IPMU)07/08/2026, 09:00
Internal quantum reference frames provide a general framework for handling symmetries in quantum theory, with applications ranging from quantum gravity and gauge theories to quantum information and foundational physics. I will first introduce the formalism in simple mechanical systems, before turning to classical gravity. There, I will motivate the need for internal, dynamical frames in...
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Tadashi Takayanagi07/08/2026, 10:00
The holographic principle provides a powerful framework to study quantum gravity by establishing a connection between bulk geometry and boundary quantum information. While holographic entanglement entropy serves as a standard tool to map algebraic properties in quantum information to geometric properties in gravity, this only cares about the space-like correlations. To explore time-like...
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Kotaro Tamaoka07/08/2026, 11:30
Understanding the black hole interior remains one of the central challenges in quantum gravity and holography. In this talk, we will argue that a special extremal slice inside an AdS black hole is dual to an absolutely maximally entangled (AME) state. This claim is supported by showing that the holographic n-th Rényi entropies are independent of n for arbitrary bipartitions of the...
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Masazumi Honda07/08/2026, 13:30
In my talk, I will overview application of quantum computation to numerical approaches in high energy physics. I will start with basics of quantum computation and then introduce how to put quantum field theories on quantum computers. Then I will introduce previous works on quantum simulations of quantum field theories and discuss our recent work on application to non-equilibrium physics of...
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Arnab Pradhan07/08/2026, 14:30
Hamiltonian lattice gauge theories provide access to important physics that remains difficult to study using conventional Euclidean methods. Quantum computers are naturally suited to implementing such formulations. With near-term quantum hardware in mind, we present an efficient framework for incorporating fermionic matter into 3+1-dimensional lattice gauge theories. The key idea is to combine...
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Patrick Angus Hager07/08/2026, 15:30
Thermal correlation functions depend on widely separated scales: the temperature, particle masses, and the external kinematics. In vacuum, the method of regions organises such expansions and tells us which modes an effective theory must contain. At finite temperature the picture is incomplete. Beyond the familiar hard and soft contributions, thermal correlators contain terms exponentially...
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Kyohei Mukaida07/08/2026, 16:30
Equal-time expectation values, rather than asymptotic scattering amplitudes, are the natural observables in many time-dependent quantum systems. In this talk, I will present cutting rules for such in-in correlators in the Schwinger–Keldysh formalism, which reorganize perturbative contributions in a way that makes their causal structure transparent. We will then discuss cosmological correlators...
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Wei-Chen Lin07/08/2026, 17:30
We use the Euclidean path-integral method to approximate the wavefunction of the universe, focusing on a scenario in which a single Euclidean wormhole instanton dominates the path integral. This solution, which connects two Lorentzian spacetimes, provides an approximation to the emergence of classical spacetime in quantum cosmology. Beyond the background level, perturbations about this...
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