The 2018 annual symposium took place on Friday, November 9, 2018

The symposium was chaired by Michel Pérault

**Schedule of Speakers**

2:00 pm_ **Jean-Marc Berroir ** Welcome

2:10 pm_ **Jean-Loup Puget ** “Testing the inflationary paradigm”

2:50 pm_ **François Boulanger ** “Cosmology and the astrophysics of foreground interstellar emission”

3:30 pm_ ** Marko Medenjak ** “Quantum and classical systems out-of-equilibrium”

IPM laureate 2018, ENS – Institute Philippe Meyer

Theoretical Physics

3:50 pm_ ** Stéphane Perrard ** “Large scale dynamics in Turbulence”

JRC laureate 2018, ENS – ICFP, Department of Physics

Statistical physics

4:10 pm_ *Coffee Break *

4:40 pm_ **Andrei Lazanu ** “Topological defects and the large-scale structure of the Universe”

JRC laureate 2018, ENS – ICFP, Department of Physics

Astrophysics

5:00 pm_ **Manuel Gessner ** “Quantum metrology and quantum correlations”

JRC laureate 2018, ENS – ICFP, Department of Physics

Quantum physics

5:20 pm_ ** Yashar Akrami ** “Beyond the concordance model in the era of precision cosmology : An interplay between cosmological observations and fundamental physics”

JRC laureate 2018, ENS – ICFP, Department of Physics

Astrophysics

5:40 pm_ **Bruno Le Floch ** “Testing dualities in gauge theories”

IPM laureate 2018, ENS – Institute Philippe Meyer

Theoretical Physics

6:00 pm_ *Cocktail apéritif*

**Abstracts**

**Jean-Loup Puget “Testing the inflationary paradigm” **

An inflationary phase in the primordial universe is a paradigm that best responds to the contradictions of a classic big bang model.

Almost all generic predictions have been verified with the Planck mission data. One of them, the presence of waves primordial gravitational, has not been verified. There are many inflation models (too much !). The state of observations will be discussed today and in the future and their implications for models inflation and in particular the problem of interstellar dust.

**François Boulanger “Cosmology and the astrophysics of foreground interstellar emission”**

Over the last decades, the successes of ever more powerful experiments have transformed observational cosmology into a high precision science. This success story has open a new era where foremost questions about our Universe nomore depend solely on getting new data with higher sensitivity, because the cosmological signals to be discovered are small compared to the foreground emission from our Galaxy.

Indeed, the dusty magnetized Galactic interstellar medium has become a major hindrance to detect the signature of primordial gravitational waves in the polarization of the Cosmic Microwave Background (CMB), as well as CMB spectral distortions and the 21cm line emission of neutral hydrogen from the epoch of reionization of the Universe when the first stars and galaxies formed. Within this new research context, observational cosmology is tied to the challenge of characterizing statistically the complexity arising from non-linear interstellar physics.

Two research fields, which have progressed in the past independently, have become interconnect opening an exciting interface central to our research at ENS.

**Marko Medenjak “Quantum and classical systems out-of-equilibrium”**

Understanding how the collective universal features of large systems arise from the microscopic description is one of the greatest endeavors of statistical physics.

In my research I focus on identifying and understanding the mechanisms and principal objects in quantum and classical systems out-of-equilibrium and on development of new methods that enable the calculation of relevant physical quantities analytically.

**Stéphane Perrard “Large scale dynamics in Turbulence” **

In hydrodynamic turbulence, tremendous research effort have been devoted to the energy transfert toward small scales, where dissipation eventually takes place. Less is known on the dynamics of the large scale structures that can be erratically fed by the smaller scales. Recently, numerical and theoretical works have revealed that the large scales may be in thermal equilibrium, but no experimental proof has been provided. I will present how direct and indirect signatures of turbulent fluctuations at large scales could be revealed using simple laboratory experiments, and how the thermal equilibrium hypothesis could be tested experimentally

**Andrei Lazanu “Topological defects and the large-scale structure of the Universe”**

My research interests include cosmological signatures of topological defects, the formation of the large-scale structure of the Universe, the effects of primordial non-Gaussianity and constraining modified gravity and dark energy models. In particular, I am interested in modelling higher-order statistics for large-scale structure and exploiting bispectrum estimators for constraining cosmological parameters using optical and radio surveys.

**Manuel Gessner “Quantum metrology and quantum correlations”**

Quantum metrology strives to overcome classical limits on the precision of measurements using nonclassical properties of quantum mechanical systems.

At the ENS, I plan to study in particular the problem of multiparameter quantum metrology with applications such as quantum imaging and field sensing. For my research, I employ concepts from quantum information theory to characterize atomic and quantum optical systems of varying complexity, often in close collaborations with experimental groups.

**Yashar Akrami “Beyond the concordance model in the era of precision cosmology : An interplay between cosmological observations and fundamental physics” **

In the era of precision cosmology, various large-scale cosmological collaborations have already been formed with the ambitious objective of mapping the entire observable region of spacetime. This has provided us with detailed understanding of the universe, its birth, evolution, future and elementary building blocks. Cosmological, multi-messenger observations play an essential role also in the development of fundamental physics, which ranges from understanding the nature of gravity and other fundamental interactions to addressing basic questions about the structure of spacetime. In this talk, I will give a brief overview of my contributions to this exciting journey from the precise cosmological measurements to the understanding of the universe, today and in our low-energy epoch, and far in the past when it was dramatically more energetic and exotic. I will explain how cosmologists can also deepen our understanding of fundamental physics, in an attempt to go beyond the standard framework of cosmology.

**Bruno Le Floch “Testing dualities in gauge theories” **

Quantum field theories that are very different at small scales may nevertheless describe the same physics at long distances. Such theories are called infrared dual. I will explain how dualities between supersymmetric gauge theories are found and tested, and how they can be enriched by considering various non-local operators.