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The SEMPARIS seminar webserver hosts annoucements of all seminars taking place in Paris area, in all topics of physics, mathematics and computer science. It allows registered users to receive a selection of announcements by email on a daily or weekly basis, and offers the possibility to archive PDF or Powerpoint files, making it available to the scientific community.   [ More information ]


Upcoming Seminars
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Thursday 28 May 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th|math.MP
Johannes Kellendonk ( Institut Camille Jordan, Université Claude Bernard Lyon 1 ) TBA

Thursday 28 May 2020, 16:00 at IHP, Online
( Zoom meeting link: https://zoom.us/j/91944484613 )
RENC-THEO (Rencontres Théoriciennes) hep-th
Thomas Hartman ( Cornell University ) Replica wormholes and the black hole information paradox
Abstract: I will review recent progress on the black hole information puzzle involving the appearance of "islands" in the black hole interior. The islands arise from the replica trick used to calculate the entropy of Hawking radiation. This entropy receives large non-perturbative corrections from gravitational instantons called replica wormholes, which connect multiple copies of the black hole through the interiors. In several toy models where these contributions can be calculated explicitly, the resulting entropy is consistent with unitary black hole evaporation.

Thursday 4 June 2020, 11:40 at IHP, 324 RENC-THEO (Rencontres Théoriciennes) hep-th
Costas Bachas ( ENS ) TBA

Friday 5 June 2020, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774 COURS (Cours) physics
Michele Vallisneri ( JPL and IPhT ) CANCELED: Gravitational waves in a nutshell (1/5)
Abstract: (Canceled: due to some recent issues related to covid19 flu)

Friday 5 June 2020, 11:00 at APC, Amphithéatre Pierre Gilles de Gennes APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Irina Dvorkin ( IAP ) TBA

Wednesday 10 June 2020, 14:00 at LKB, Visioconférence Zoom
( Lien zoom : https://us02web.zoom.us/j/81651124927? pwd=Z3pTNlNWeENMclJOeFgzM21DK2xCUT09 )
SEM-LKB (Séminaire du Laboratoire Kastler Brossel) quant-ph
Tilman Pfau ( University of Stuttgart ) Quantum Droplets and Supersolidity in a Dipolar Quantum Gas
Abstract: Dipolar interactions are fundamentally different from the usual van der Waals forces in real gases. Besides the anisotropy the dipolar interaction is nonlocal and as such allows for self organized structure formation. In 2005 the first dipolar effects in a quantum gas were observed in an ultracold Chromium gas. By the use of a Feshbach resonance a purely dipolar quantum gas was observed three years after [1]. Recently it became possible to study degenerate gases of lanthanide atoms among which one finds the most magnetic atoms. Similar to the Rosensweig instability in classical magnetic ferrofluids self-organized structure formation was expected. In our experiments with quantum gases of Dysprosium atoms we could observe the formation of a droplet crystal [2]. In contrast to theoretical mean field based predictions the super-fluid droplets did not collapse. We find that this unexpected stability is due to beyond mean-field quantum corrections of the Lee-Huang-Yang type [3,4]. We observe and study self-bound droplets [5] which can interfere with each other. We also observe self-organized stripes in a confined geometry [6] and collective scissors mode oscillations of dipolar droplets [7Recently in the striped phase also phase coherence was observed in Dysprosium and Erbium experiments, which is evidence for a supersolid state of matter [8]. Upon crossing the transition to the dipolar supersolid a Goldstone mode appears, which we have observed recently [9]. The existence of this mode proofs the superfluid stiffness or the so-called phase rigidity of this new state of matter. Despite the lack of symmetry protection, also a Higgs mode was predicted to be observable in a finite system [10]. References [1] T. Lahaye, et al., Rep. Prog. Phys. 72, 126401 (2009) [2] H. Kadau, et al., Nature 530, 194 (2016) [3] T.D. Lee, K. Huang, and C. N. Yang, Phys. Rev. 106, 1135 (1957), D.S. Petrov, Phys. Rev. Lett. 115, 155302 (2015). [4] I. Ferrier-Barbut, et al., Phys. Rev. Lett. 116, 215301 (2016) [5] M. Schmitt, et al., Nature 539, 259 (2016) [6] M. Wenzel, et al., Phys. Rev. A 96 053630 (2017) [7] I. Ferrier-Barbut, et al., Phys. Rev. Lett. 120, 160402 (2018) [8] F. Böttcher, et al. Phys. Rev. X. 9, 011051 (2019), see also L. Tanzi, et al. Phys. Rev. Lett. 122, 130405 (2019), L. Chomaz et al., Phys. Rev. X 9, 021012 (2019) [9] M. Guo, et al. Nature. 574, 386--389 (2019) [10] J. Hertkorn et al., Phys. Rev. Lett. 123, 193002 (2019)

Thursday 11 June 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th
Yves André ( IMJ, Paris ) De l’impossibilité de calculer algébriquement la position d’une planète à temps donné à la structure générale des relations de périodes

Friday 12 June 2020, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774 COURS (Cours) physics
Michele Vallisneri ( JPL and IPhT ) CANCELED: Gravitational waves in a nutshell (2/5)
Abstract: (Canceled: due to some recent issues related to covid19 flu)

Friday 19 June 2020, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774 COURS (Cours) physics
Michele Vallisneri ( JPL and IPhT ) CANCELED: Gravitational waves in a nutshell (3/5)
Abstract: (Canceled: due to some recent issues related to covid19 flu)

Friday 26 June 2020, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774 COURS (Cours) physics
Michele Vallisneri ( JPL and IPhT ) CANCELED: Gravitational waves in a nutshell (4/5)
Abstract: (Canceled: due to some recent issues related to covid19 flu)

Friday 26 June 2020, 11:00 at APC, TBA APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Zvi Bern ( UCLA ) TBA
Abstract: TBA

Friday 3 July 2020, 10:00 at IPHT, Salle Claude Itzykson, Bât. 774 COURS (Cours) physics
Michele Vallisneri ( JPL and IPhT ) CANCELED: Gravitational waves in a nutshell (5/5)
Abstract: (Canceled: due to some recent issues related to covid19 flu)

Tuesday 6 October 2020, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Eric Laenen ( Nikhef ) TBA

seminars from series at institute
in subject with field matching

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