### Past Events

### QUAST Seminar: Krishna Jalan

2024-10-31**Speaker:** Krishna Jalan

**Title:** Generalized second law for non-minimally coupled matter theories

**Abstract:** In this talk, I will give a brief overview of the generalized second law (GSL) of black hole thermodynamics. In particular, we will see how the GSL works out for non-minimally coupled matter theories within the context of higher curvature gravity theories. Previous proofs in the literature have extensively addressed the GSL in various gravity theories, but they have uniformly assumed that matter sectors couple minimally to gravity. In this presentation, we will explore a straightforward generalization of the GSL to scenarios involving non-minimally coupled matter, specifically scalar fields, within an effective field theory framework.

### QUAST seminar: Jan Głowacki

2024-10-30Speaker: Jan Głowacki

Title: Relativistic operational quantum reference frames

Abstract: I will be sharing some recent insights related to applying the operational approach to quantum reference frames (QRFs) in relativistic contexts. I will begin by briefly reviewing the principles of operational QRFs to then apply them in the context of the Poincare group and discuss the emerging notion of relational local observables. This perspective can be further generalized to gauge theories by replacing the Poincare group by an arbitrary principal bundle. In this context, the concepts of external frame transformations, gauge-invariance and diff-invariance can be understood in a relational and operational manner. If time allows, I will also mention work in progress on how indefinite geometries can be incorporated in this picture, how far we in establishing this approach as a relational and mathematically sound foundation for QFT, and its connections to quantum measurement theory in this context. I would also be happy to exchange some ideas about how the `thermal modular type-reduction’ phenomena could be seen from this perspective.

### Quantum Extreme Universe: Matter, Information and Gravity 2024

2024-10-21 to 2024-10-25Website | OIST organizer: Philip Höhn (Qubits and Spacetime Unit) | ExU Organizer: Tadashi Takayanagi (Yukawa Institute for Theoretical Physics, Kyoto) | OIST members are welcome to attend all scientific sessions. Please show your OIST badge when entering the venue.

### [Quast Seminar] Dario Cafasso

2024-05-30Title: Quantum Time-Dilation in Qubit Hypersurfaces

Abstract: The use of quantum spin systems to study the phenomenon of quantum time dilation leads to new insights into the quantum description of gravity. The basis of this description is the Page and Wootters mechanism, where entanglement between two quantum systems allows one to act as a clock for the other, influencing its time evolution. Intriguingly, when the clock system experiences a "gravitational-like interaction", the resulting time evolution can be described by a Time-Dilated Schrödinger equation. This equation includes a "redshift operator," a purely quantum effect that mimics gravitational time dilation. Here we discuss a novel, finite-dimensional framework in which a network of qubit systems can be used as a "global" clock for another non-interacting component of the universe. The result is the Time-Dilation induced Interaction Transfer (TiDIT) mechanism. TiDIT describes how time dilation due to the interaction of a qubit effectively changes the interaction between previously non-interacting parts of the universe. We will explore this concept with a practical example using two coupled qubits as a model for the quantum clock.

### [QUAST Seminar] Mykhaylo Usatyuk: Closed universes in two dimensional gravity

2024-05-14Dr Mykhaylo Usatyuk

Kavli Institute for Theoretical Physics, Santa Barbara

### [QUAST Seminar] Ronak Soni: Extremality as a Consistency Condition on Subregion Duality

2024-05-07Ronak Soni

University of Cambridge, DAMTP

### [QUAST Seminar] Ana-Maria Raclariu: Entanglement, soft modes and celestial holography

2024-04-25Ana-Maria Raclariu

King's College London

### [QUAST Seminar] Aaron Poole: Thermodynamics of accelerating AdS_4 black holes from the covariant phase space

2024-03-18Thermodynamics of accelerating AdS_4 black holes from the covariant phase space

Aaron Poole

Kyung Hee University, South Korea

### [QUAST Seminar] Bilyana Tomova - Asymptotic symmetries of gravity

2023-11-20# Asymptotic symmetries of gravity,

Bilyana Tomova,

OIST

### [QUAST Seminar]: Elliott Gesteau - Large N von Neumann algebras and the renormalization of Newton's constant

2023-11-15Large N von Neumann algebras and the renormalization of Newton's constant

Elliott Gesteau

Caltech