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I will describe the dynamics of classical disordered macroscopic models
(of p-spin kind) completely isolated from any environment in a classical
setting that reproduces the "quantum quench" protocol. The asymptotic
dynamics can reach a steady state of Gibbs-Boltzmann kind for
non-integrable (p > 2, multi-body) interactions while, instead, they
approach a stationary state of Generalized Gibbs Boltzmann type in
integrable (p = 2, two-body) cases. Interesting phase transitions will be
discussed in both cases. Methods to sample efficiently the asymptotic
measures will also be discussed. This talk summarizes work done in
collaboration with D. Barbier, R. Gonzalez-Albaladejo, G. Lozano, N.
Nessi, M. Picco, D. Stariolo, and A. Tartaglia.

The talk will be based mostly on “The complex Liouville string: the worldsheet” by Scott Collier, Lorenz Eberhardt, Beatrix Mühlmann, Victor A. Rodriguez, https://arxiv.org/abs/2409.18759.

Kai-Siang Chen

As a striking manifestation of quantum entanglement, nonlocality has long played a pivotal role in shaping our understanding of the quantum world. When considering a Bell test involving three parties, we may even find a remarkable situation where the nonlocality in two bipartite subsystems forces the remaining bipartite subsystem to exhibit nonlocality. This intriguing effect, dubbed nonlocality transitivity, was first identified in the non-quantum non-signaling world in 2011. However, whether such transitivity could manifest within quantum theory has remained unresolved—until now. Here, we provide the first affirmative answer to this open problem at the level of quantum states, thereby showing that there exists a quantum-realizable notion of nonlocality transitivity. Specifically, by leveraging the possibility of Bell-inequality violation by tensoring, we analytically construct a pair of nonlocal bipartite states such that simultaneously realizing them in a tripartite system induces nonlocality in the remaining bipartite subsystem. En route to showing this, we also prove that multiple copies of the W-state marginals uniquely determine the global compatible state, thus establishing another instance when the parts determine the whole. Surprisingly, the nonlocality transitivity of quantum states also occurs among the reduced states of Haar-random three-qutrit pure states. We further show that the transitivity of quantum steering can already be demonstrated with the marginals of a three-qubit W state, showing again another noteworthy difference between the two forms of quantum correlations. Finally, we present a simple method to construct quantum states and correlations that are nonlocal in all their non-unipartite marginals, which may be of independent interest.

Bérengère Dubrulle (IRAMIS/SPEC)

Abstract: 

Turbulence, a phenomenon observed by physicists in natural and laboratory flows, is thought to be described by Navier-Stokes equations (NSE). Yet, it is not yet known whether the Cauchy problem is well posed for these equations, and whether solutions of finite energy are regular or unique. In the physics community, the “singularity hypothesis” is generally discarded, following the reasonable principle that “singularities are a mathematical curiosity, in nature they do not exist”.

In these lectures, I will discuss how recent progresses in mathematics, numerical simulations and laboratory experiments changed such simple vision leading to a new picture where quasi-singularities living beyond Kolmogorov scale play a central role.

Topics covered:

• The basic empirical laws of turbulence
• Some mathematical aspects of Navier-Stokes equations
• Symmetries and their consequences
• Singularities and anomalous laws
• Predictability of turbulence

Calabi-Yau compactifications of string theory lead to quantum field theories in four dimensions with chiral matter. Calculating parameters of the low-energy effective theory in general compactifications requires the Ricci-flat metric on the Calabi-Yau manifold. Such metrics are not known analytically. In this talk, we discuss how to approximate the Ricci-flat metric using neural networks. The accuracy of the numerical metrics is assessed for K3 and the quintic threefold. In the standard embedding, we calculate Yukawa couplings for compactifications on various Calabi-Yau geometries and show the existence of hierarchies. This is an initial step toward a first principles calculation of particle masses from string theory.

Conférence-visite de l’IPhT le 17 juin (de 9hà 11h dans l’amphi Bloch, bât 773 Orme des Merisiers, centre CEA de Saclay (144 places)

• 1. La physique quantique par le prisme des symétries

Intervenant: Thibaud Raymond

La physique quantique est notre meilleure description actuelle des phénomènes se produisant aux plus petites échelles de la matière. Elle semble parfois étrange — presque paradoxale — lorsque confrontée à nos intuitions du quotidien. Pourtant, elle est la source des prédictions expérimentales les plus précises et mieux vérifiées parmi toutes les sciences. Comment peuvent bien faire les physiciens pour la manipuler avec autant de succès ? On verra que la notion de symétrie joue un rôle central dans une histoire qui nous emmènera des spectres d’absorption des atomes à la description des interactions fondamentales en passant par le tableau périodique des éléments, et qui continue activement de nos jours.

-questions

• 2. film IPhT, une expérience théorique

•  3. Les trous noirs et le paradoxe de l’information

Intervenant: Raphaël Dulac

Un trou noir est une région de l’espace où la gravité est tellement intense que rien ne peut en sortir, pas même la lumière. D’après la relativité générale, toute information sur ce qui tombe dedans semble perdue à jamais. Mais la mécanique quantique prédit que l’information ne peut jamais disparaître. Cette tension est communément appelée le paradoxe de l’information dans les trous noirs. Nous expliquerons ce qu’est un trou noir ainsi que ce paradoxe, rendu célèbre par Stephen Hawking. Nous présenterons une possibilité de résolution moderne à l’aide d’une théorie de gravité quantique

-questions

Simplified false vacuum decay rates and the Standard Model lifetime

TBA.

Bérengère Dubrulle (IRAMIS/SPEC)

Abstract: 

Turbulence, a phenomenon observed by physicists in natural and laboratory flows, is thought to be described by Navier-Stokes equations (NSE). Yet, it is not yet known whether the Cauchy problem is well posed for these equations, and whether solutions of finite energy are regular or unique. In the physics community, the “singularity hypothesis” is generally discarded, following the reasonable principle that “singularities are a mathematical curiosity, in nature they do not exist”.

In these lectures, I will discuss how recent progresses in mathematics, numerical simulations and laboratory experiments changed such simple vision leading to a new picture where quasi-singularities living beyond Kolmogorov scale play a central role.

Topics covered:

• The basic empirical laws of turbulence
• Some mathematical aspects of Navier-Stokes equations
• Symmetries and their consequences
• Singularities and anomalous laws
• Predictability of turbulence

Intervenante: Laura Foini

Résumé disponible ultérieurement.

Bérengère Dubrulle (IRAMIS/SPEC)

Abstract: 

Turbulence, a phenomenon observed by physicists in natural and laboratory flows, is thought to be described by Navier-Stokes equations (NSE). Yet, it is not yet known whether the Cauchy problem is well posed for these equations, and whether solutions of finite energy are regular or unique. In the physics community, the “singularity hypothesis” is generally discarded, following the reasonable principle that “singularities are a mathematical curiosity, in nature they do not exist”.

In these lectures, I will discuss how recent progresses in mathematics, numerical simulations and laboratory experiments changed such simple vision leading to a new picture where quasi-singularities living beyond Kolmogorov scale play a central role.

Topics covered:

• The basic empirical laws of turbulence
• Some mathematical aspects of Navier-Stokes equations
• Symmetries and their consequences
• Singularities and anomalous laws
• Predictability of turbulence