Quantum Information Journal Club: 'Programming quantum matter made with light and atoms'
2025-12-03 11:30 - 12:30 (Europe/Madrid) | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Cristian Tabares

Venue & Time: 11:30 / Gray Room 3

Abstract: Current experimental quantum devices do not yet meet the requirements for building fault-tolerant quantum computers, but they can still be used to address many-body problems as analogue quantum simulators. Furthermore, recent experimental advances [1-4] are enabling these simulators to operate in a programmable manner [5], where their dynamics can be used as resources to generate a set of (non-universal) quantum gates. These controllable systems are able to generate highly entangled states, but a natural question is how to use these resources for quantum simulation purposes.

In this seminar we will discuss two different approaches. The first one will be based on state preparation, demonstrating how a classical device can be used to assist the analogue quantum simulator in the task of many-body state preparation [6,7] with variational algorithms. We will focus on fermionic atoms in optical lattices [8], constructing for ground-state preparation of local and extended Fermi-Hubbard models that show considerable improvements with respect to equivalent adiabatic methods. Then, in the second part of the talk, we will introduce an algorithm specifically tailored for analog quantum simulators to accurately recover their ground state properties [9]. Using only global time evolution under a target Hamiltonian, our algorithm avoids the need for local control that is typically required in conventional quantum phase estimation.

These results provide programmable quantum simulators with a new set of tools that further leverage their current capabilities. Overall, our work opens new avenues for analog simulators to make a wider and more efficient exploration of their relevant many-body Hilbert space.

[1] X. Zhang et al., Science 379, 278-283 (2023).
[2] C. Kokail et al., Nature 569, 355–360 (2019).
[3] S. Ebadi et al., Nature 595, 227–232 (2021).
[4] D. Bourgund et al., Nature 637, 57–62 (2025).
[5] A. J. Daley et al., Nature 607, 667–676 (2022).
[6] C. Tabares, A. Muñoz de las Heras, L. Tagliacozzo, D. Porras, and A. González-Tudela, Phys. Rev. Lett. 131, 073602 (2023).
[7] A. Muñoz de las Heras, C. Tabares, J. Schneider, L. Tagliacozzo, D. Porras, and A. González-Tudela., Phys. Rev. Research 6, 013299 (2024).
[8] C. Tabares, C. Kokail, P. Zoller, D. González-Cuadra and A. González-Tudela, PRX Quantum 6, 030356 (2025).
[9] C. Tabares, D. S. Wild, J. I. Cirac, P. Zoller, A. Gonzalez-Tudela, and D. González-Cuadra, arXiv:2511.04434 (2025).

SPS Journal Club: 'On the K-point in moduli space'
2025-12-04 12:00 - 13:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Alessandra Grieco (IFT)

Venue & Time: Red Room / 12:00

Abstract: We study a class of infinite-distance loci, referred to as K-points, in one-parameter complex-structure moduli spaces of type IIB string theory compactified on Calabi-Yau manifolds. We show that around K-points the effective four-dimensional supergravity exhibits certain unusual properties. The two most prominent being that the leading order dependence of the prepotential on the gauge couplings is non-perturbative and that the leading gauge kinetic terms in the action vanish when evaluated on an anti self-dual graviphoton background. These properties are shared with the conifold locus in moduli space, rather than the large complex-structure locus. The conifold locus is well-known to arise from integrating out a charged BPS state, and so the similarities suggest that the K-point also arises from integrating out a BPS state. We develop such an interpretation, finding that it corresponds to a BPS state which is extremely light, whose mass in Planck units is doubly-exponentially small in the distance to the K-point. The state behaves as if it had complex charges, or as if it couples to the self-dual and anti self-dual parts of the graviphoton differently. Assuming such an integrating-out scenario is indeed the correct physics for the K-point, we discuss the implications for our understanding of infinite distances in moduli space and for the Swampland Distance Conjecture.

Seminar: 'The Tolerable Inhomogeneity of the Baryon Asymmetry'
2025-12-04 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Stefan Stelzl from EPFL, Lausanne

Venue & Time: Red Room / 15:00

Abstract:

In this talk I present the implications of precision measurements of light element abundances in concordance with the Cosmic Microwave Background for scenarios of physics beyond the Standard Model that generate large inhomogeneities in the baryon-to-photon ratio. We show that precision Big Bang Nucleosynthesis (BBN) imposes strong constraints on any mechanism that produces large scale inhomogeneities at temperatures of the order or below a TeV. In particular, we find that inhomogeneities of the order of at comoving length scales larger than the comoving horizon at the temperature of are in conflict with the measured light element abundances. I then briefly highlight the phenomenological consequences thereof.

Old Journal Club: 'Field Theories with Superconductor Solutions'
2025-12-04 17:00 - 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Lorenzo Paoloni (IFT) will present :“Field Theories with Superconductor Solutions”, Nuovo Cim. 19 (1961) 154–164 de J. Goldstone.
Venue & Time: Blue Room / 17:00

Abstract: The conditions for the existence of non-perturbative type « superconductor » solutions of field theories are examined. A non-covariant canonical transformation method is used to find such solutions for a theory of a fermion interacting with a pseudoscalar boson. A covariant renormalisable method using Feynman integrals is then given. A « superconductor » solution is found whenever in the normal perturbative-type solution the boson mass squared is negative and the coupling constants satisfy certain inequalities. The symmetry properties of such solutions are examined with the aid of a simple model of self-interacting boson fields. The solutions have lower symmetry than the Lagrangian, and contain mass zero bosons.
More info: https://inspirehep.net/literature/12289

31st Xmas Workshop
2025-12-09 09:30 - 2025-12-11 18:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
From December 9th to December 11th 2025 we will celebrate the XXXI edition of our annual Christmas Workshop at the Instituto de Física Teórica (IFT) UAM-CSIC.
Leading experts will meet at the IFT to discuss recent developments in (astro) particle physics, phenomenology, cosmology, string theory, and quantum information.
More info.
Organizers:

Alejandro Bermudez
David Cerdeño
Gregorio Herdoíza
Miguel Montero
Pilar Coloma
Sven Heinemeyer
Yashar Akrami

Confirmed speakers:

Massimo Bianchi (Rome)
Diego Blas (IFAE)
Rebecca Gozzini (IFIC)
Aram Harrow (MIT)
Yolanda Lozano (U Oviedo)
Gonzalo Palma (Chile U.)
Ryan Plestid (CERN)
Carsten Urbach (U. Bonn)
Alexander Westphal DESY)
Giulia Zanderighi (MPI Munich)

posterIFTXmas25.pdf

Joint Colloquium IFT + ICMAT: 'Geometry of gauge theories in two dimensions'
2025-12-12 09:30 - 14:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Joint ICMAT-IFT Colloquium
After the colloquium, the traditional “Farewell to the Year” party will take place in the CFTMAT cafeteria.
Speaker: Oscar García-Prada (ICMAT-CSIC)
Date: Friday, 12 December 2025 – 12:00
Place: Blue Room
Abstract:
I will describe several geometric aspects of different gauge theories on Riemann surfaces that originate in four-dimensional Yang–Mills theories. A common theme is the appearance of various types of Higgs fields. I will provide some basic mathematical and historical background.

Seminar: 'Active Galactic Nuclei as Laboratories for Fundamental Physics'
2025-12-15 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Gonzalo Herrera (MIT & Harvard)
Venue & Time: Red Room / 15:00

Abstract: The vicinity of supermassive black holes at the center of Galaxies represents one of the most extreme environments in the Universe. In Active Galactic Nuclei (AGN), intense gravitational fields, relativistic particle acceleration, strong magnetic fields, and dense ambient gas and radiation coexist in conditions unmatched by other astrophysical sources or Earth-based laboratories. Recent high-energy neutrino observations from the IceCube collaboration and their electromagnetic counterparts from AGN have revolutionized the field of multi-messenger astronomy, providing the first direct window into the hadronic and leptonic processes operating at these cosmic accelerators, and opening new opportunities to test fundamental physics at energies and densities beyond terrestrial reach.
Here I will discuss how these environments can be exploited as laboratories for fundamental physics. I will first focus on dark matter–Standard Model interactions, showing how dark matter scattering with cosmic rays, neutrinos and gamma-rays can can lead to observable signatures on Earth. Second, I will consider other exotic phenomena that may occur independently on the dark matter background in these environments, such as photon-axion-like particle oscillations and microscopic black hole production from cosmic-ray collisions. Finally, I will conclude by showing how AGN can boost the cosmic neutrino background to higher energies via Standard Model processes, giving us a viable and promising pathway to detect the oldest particles in the Universe.

Pheno Journal Club: 'How large can lepton mixing be?'
2025-12-16 15:00 - 16:00 | Gray Room 3, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Speaker: Sergio Rodríguez Benítez (IFT)
Venue & Time: Grey Room 3 / 15:00
Abstract: We show that, contrary to common expectations, the observed charged leptons can have a substantial mixing with new heavier fermions, at the level of 20%. This can happen, in the language of effective theories, when the effect of mixing with heavier fermions vanishes at tree level in operators of mass-dimension 6 (or it is suppressed by the small charged lepton masses), a cancellation that can be naturally ensured by symmetries. Using a model that realizes this scenario we consider all current direct and indirect constraints and show that experimental constraints on the mixing are so mild that, given the current direct limit on the mass of the heavy fermions, theoretical considerations become the leading current constraints on the mixing. We also estimate the sensitivity to the mixing at future experiments, including the high-luminosity phase of the LHC and, most notably, the FCCee, and FCC-hh. We find a pattern in which the reach of direct searches in hadron machines makes theoretical considerations lead the limits while the precision of lepton machines can beat these theoretical considerations. We find that the FCC can finally reach per milleprecision in the mixing squared of the charged leptons.

Prueba Coloquio
2025-12-22 08:00 - 17:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
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Prueba Journal Club
2025-12-22 08:00 - 2025-12-24 17:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
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Prueba seminario
2025-12-23 08:00 - 2025-12-26 17:00 | Gray Room 1, Instituto de Física Teórica, C/ Nicolás Cabrera 13-15, Cantoblanco, Madrid, Madrid, 28049, Spain
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Prueba workshop
2025-12-26 08:00 - 17:00 | Blue Room, Instituto de Física Teórica (IFT) - C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
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Seminar by Cristina Puchades Ibáñez (University of Mainz)
2026-01-15 15:00 - 16:00
TBA

Seminar by Piotr Toczek (Warsaw University)
2026-01-22 15:00 - 16:00

IFT seminar Ennio Salvioni
2026-01-29 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

IFT seminar Tamara Vázquez Schröder
2026-02-02 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Yushi Mura (KEK)
2026-02-05 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Title: ‘Probing CP violation for electroweak baryogenesis in two Higgs doublet
model’
Speaker: Yushi Mura (KEK)
Venue & Time: Red Room / 15:00
Abstract: TBA

Seminar by Zoltan Fodor (Penn State U.)
2026-02-09 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Miguel Escudero
2026-02-23 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
Seminar (Theoretical Physics, general interest)

Date: 23/02/2025
Time: 15:00 – 16:15
Red Room
Title: TBA
Speaker: Miguel Escudero

Institution: CERN

Seminar by Robert Brandenberger (McGill)
2026-03-02 15:00 - 17:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Leandros Perivolaropoulos (Ioannina)
2026-03-05 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Roberto Emparan (Universidad de Barcelona)
2026-03-23 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Jose Beltran (Salamanca)
2026-04-13 15:00 - 16:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain

Seminar by Isaac Tutusaus (ICE, Barcelona)
2026-04-20 15:00 | IFT Seminar Room/Red Room, Instituto de Física Teórica (IFT) -C. Nicolás Cabrera, 13-15, Fuencarral-El Pardo, Madrid, 28049,, Spain
