Luis Foa Torres' home page

The Santiago School of Physics 2025: Additional material

Wed, 30 Jul 2025 00:00:00 +0000

Lectures on “Topological States in Condensed Matter”, July 30, 2025.

Notes of part 1 (Basics of band structures and SSH model): part1.pdf

Slides of part 2 (Quantum Hall effects): part2.pdf

Course “From graphene to topological insulators” available on YouTube.

Talk on quantum Hall effects also available on YouTube.

One-way transport without time-dependent fields

Mon, 03 Aug 2020 02:12:22 +0000

A direct current (dc) between two electrodes is normally linked to the flow of the electrons in response to an applied bias voltage between those leads.

However, during the last years many of us have been actively pursuing new ways of generating a current even at zero bias voltage. One of the most popular alternatives is the use of time-dependent potentials to produce a quantum pump.

But there is yet another more subtle way which (1) does not rely on time-dependent potentials and (2) can be built-in the band structure of a system. This way consists on crafting one-way states able to carry directional transport of either charge, valley or spin.

Floquet Topological Insulators

Mon, 03 Aug 2020 02:06:28 +0000

Floquet Topological Insulators are topological phases resulting from strong light-matter interaction, or more generally, time-dependent perturbations (the name Floquet appears as Floquet theory is the prevalent theory for dealing with such effects). These topological phases can be achieved even in materials that natively lack topological states. Therefore, by using light one can achieve topological states similar to those in topological insulators.

Topological Insulators (TIs) are a recent family of exotic materials with a few intriguing properties. They are insulators in the bulk but their edges support propagating states bridging the bulk band-gap, much like the states emerging in the Quantum Hall effect discovered by Klaus von Klitzing in 1980 but in the case of TIs this happens without a magnetic field thanks to spin-orbit interaction. Recently, a new way of achieving properties akin to those found in quantum Hall systems started to gain attention: using a time-dependent potential to harness tunable topological properties.

Codes

Mon, 03 Aug 2020 02:03:28 +0000

This is a list of short pieces of code that may help you to reproduce some of the results in my publications. It’s by no means exhaustive nor complete nor accurate (as these codes most of the time are not the ones I used in my research) but may help you get started.

I’m planning to keep expanding on this list so stay tuned!

If you use any of these codes please check the list of references in the comments.

Join us

Mon, 03 Aug 2020 00:00:00 +0000

If you are looking for opportunities for doing research please feel free to send an email to luisfoa at gmail dot com explaining your motivation to join us. Above all I value curiosity, motivation and will to work hard to exceed your own expectations. If you are considering coming for a postdoc, there may be several options depending on your country of origin. For example, applicants based in Germany may apply for the prestigious Feodor Lynen fellowships of the Alexander von Humboldt Foundation. Applicants from Europe may profit from the Marie Sklodowska Curie Actions (MSCA IF) - Global Fellowships funding research stays in Chile.

Luis Foa Torres CV

Mon, 03 Aug 2020 00:00:00 +0000

Luis E. F. Foa Torres (b. 1978) is a condensed matter physicist. He is a Full Professor of Physics at the University of Chile (FCFM). Before he worked in Argentina as a CONICET Independent Research Scientist; in Germany as a fellow of the Alexander von Humboldt Foundation (TU Dresden); in France, at CEA-Grenoble; and in Italy, at the Abdus Salam International Centre for Theoretical Physics, first as a postdoctoral fellow, then as Junior Associate of the Condensed Matter Section (2011-2016) and, more recently, and as a Simons’ Associate of the Condensed Matter Section of ICTP (2020-present). He was awarded the ICTP Prize in 2018 in recognition of his work.

Outreach

Mon, 03 Aug 2020 00:00:00 +0000

A short list of articles in different media:

2025/08 “Física consolida investigación fundamental y traza plan para crecer con mirada global”, Interview for UNTEC on departmental strategic planning and international collaboration.

2025/07 Santiago School of Physics 2025: International winter school bringing together students from across Latin America.

2024/06 Featured in “10 Years of Supporting the Advancement of Physicists Worldwide”, Simons Foundation article highlighting the impact of the ICTP Simons Associates Program.

2024/06 “Luis Foa Torres es elegido como nuevo Director del Departamento de Física”, Announcement of election as Director of Physics Department, FCFM.

Publications

Mon, 03 Aug 2020 00:00:00 +0000

This page lists 81 publications by Luis E. F. Foa Torres, organized by year. For complete and up-to-date metrics please visit:

Highlighted entries (★) mark papers we consider particularly impactful.

2026

Charge waves and dynamical signatures of topological phases in Su-Schrieffer-Heeger chains
T. Kwapinski, M. Kurzyna, and L. E. F. Foa Torres, (2026).arXiv:2604.13682
Universal critical timescales in slow non-Hermitian dynamics
G. Pappas, D. Bautista Avilés, L. E. F. Foa Torres, and V. Achilleos, (2026).arXiv:2604.01918
Precision-Induced Irreversibility in non-Hermitian systems
L. E. F. Foa Torres, G. Pappas, V. Achilleos, and D. Bautista Avilés, (2026).arXiv:2603.22284

2025

Laser-Induced Spin Precession in Topological Insulator Devices
E. A. Rodríguez-Mena, M. Berdakin, and L. E. F. Foa Torres, Nano Letters 25, 16084–16090 (2025).publisher
A non-Hermitian loop for a quantum measurement
L. E. F. Foa Torres and S. Roche, Journal of Physics Communications 9, 065001 (2025).publisher arXiv:2408.04629
Nonsymmetric evanescent coupling in photonics
R. A. Vicencio, D. Román-Cortés, M. Rubio-Saldías, P. Vildoso, and L. E. F. Foa Torres, Physical Review A 111, 043510 (2025).publisher arXiv:2407.18174
Breaking of Lorentz invariance caused by the interplay between spin-orbit interaction and transverse phonon modes in quantum wires
D. V. Efremov, W. Ccuiro, L. E. F. Foa Torres, and M. N. Kiselev, Physical Review Research 7, L022016 (2025).publisher arXiv:2407.08613
Signatures of Floquet electronic steady states in graphene under continuous-wave mid-infrared irradiation
Yijing Liu, Christopher Yang, Gabriel Gaertner, John Huckabee, Alexey V Suslov, Gil Refael, Frederik Nathan, Cyprian Lewandowski, Luis EF Foa Torres, Iliya Esin, Paola Barbara, and Nikolai G Kalugin, Nature Communications 16, 2057 (2025).publisher
Engineering Floquet Moiré Patterns for Scalable Photocurrents
Hernán L. Calvo, Luis E. F. Foa Torres, and Matias Berdakin, Nano Letters 25, 1630 (2025).publisher arXiv:2411.07316

2024

Chiral magnon-polaron edge states in Heisenberg-Kitaev magnets
J. D. Mella, L. E. F. Foa Torres, and R. E. Troncoso, Physical Review B 110, 104433 (2024).publisher arXiv:2405.18644
Wavefunction collapse driven by non-Hermitian disturbance
J. Martínez Romeral, L. E. F. Foa Torres, and S Roche, Journal of Physics Communications 8, 071001 (2024).publisher arXiv:2404.16445
Transport of non-classical light mediated by topological domain walls in a SSH photonic lattice
G. O’Ryan Pérez, J. Medina Dueñas, D. Guzmán-Silva, L. E. F. Foa Torres, and C. Hermann-Avigliano, Scientific Reports 14, 12435 (2024).publisher arXiv:2403.10387
Topological phases of commensurate or incommensurate non-Hermitian Su-Schrieffer-Heeger lattices
M. Jangjan, L. Li, L. E. F. Foa Torres, and M. V. Hosseini, Physical Review B 109, 205142 (2024).publisher arXiv:2406.11072
Floquet Engineering of a Diatomic Molecule Through a Bichromatic Radiation Field
E. Barriga, L. E. F. Foa Torres, and C. Cardenas, Journal of Chemical Theory and Computation 20, 2559 (2024).publisher arXiv:2311.13697

2023

Entangled States Induced by Electron–Phonon Interaction in Two-Dimensional Materials
J. D. Mella, H. L. Calvo, and L. E. F. Foa Torres, Nano Letters 23, 11013 (2023).publisher

2022

Floquet topological phase transitions in a periodically quenched dimer
M. Jangjan, L. E. F. Foa Torres, and M. V. Hosseini, Physical Review B 102, 224306 (2022).publisher arXiv:2208.03544
Experimental observation of edge states in SSH-Stub photonic lattices
G. Cáceres-Aravena, B. Real, D. Guzmán-Silva, A. Amo, L. E. F. Foa Torres, and R. A. Vicencio, Physical Review Research 4 (2022).publisher
Copropagating edge states produced by the interaction between electrons and chiral phonons in two-dimensional materials
J. Medina Dueñas, H. L. Calvo, and L. E. F. Foa Torres, Physical Review Letters 128, 066801 (2022).publisher arXiv:2109.03815
Robustness of spin-polarized edge states in a two-dimensional topological semimetal without inversion symmetry
J. Mella and L. E. F. Foa Torres, Physical Review B 105, 075403 (2022).publisher arXiv:2107.12956

2021

A valley of opportunities
L. E. F. Foa Torres and S. O. Valenzuela, Physics World 11, 43 (2021).publisher
Quadrature protection of squeezed states in a one-dimensional topological insulator
J. Medina Duenas, G. O'Ryan Pérez, Carla Hermann-Avigliano, and L. E. F. Foa Torres, Quantum 5, 526 (2021).publisher arXiv:2106.00869
Spin-polarized tunable photocurrents
M Berdakin, Esteban A Rodriguez-Mena, and L. E. F. Foa Torres, Nano Letters 21, 3177 (2021).publisher arXiv:2010.11883
Quantum Hall edge states under periodic driving: A Floquet induced chirality switch
A. Huamán, L. E. F. Foa Torres, C. A. Balseiro, and Gonzalo Usaj, Physical Review Research 3, 013201 (2021).publisher arXiv:2012.07592
The 2021 Quantum Materials Roadmap
Feliciano Giustino, Manuel Bibes, Jin Hong Lee, Felix Trier, Roser Valentí, Stephen M Winter, Young-Woo Son, Louis Taillefer, Christoph Heil, Adriana I Figueroa, Bernard Plaçais, QuanSheng Wu, Oleg V Yazyev, Erik P A M Bakkers, Jesper Nygård, Pol Forn-Diaz, Silvano de Franceschi, Luis E F Foa Torres, James McIver, Anshuman Kumar, Tony Low, Regina Galceran, Sergio Valenzuela, Marius Vasile Costache, Aurélien Manchon, Eun-Ah Kim, Gabriel Ravanhani Schleder, Adalberto Fazzio, and Stephan Roche, Journal of Physics: Materials 3, 042006 (2021).publisher arXiv:2102.02644

2020

Digging into the 3D Quantum Hall Effect [Viewpoint]
L E F Foa Torres, Physics 13, 170 (2020).publisher
Topological magnonics in the two-dimensional van der Waals magnet CrI3
Esteban Aguilera, R Jaeschke-Ubiergo, N Vidal-Silva, Luis E F Foa Torres, and A S Nunez, Physical Review B 102, 024409 (2020).publisher arXiv:2002.05266
Floquet boundary states in AB-stacked graphite
Hernan L Calvo, Jose E Barrios Vargas, and Luis E F Foa Torres, Physical Review B 101, 075424 (2020).publisher arXiv:1911.02144
Topological and flat-band states induced by hybridized linear interactions in one-dimensional photonic lattices
G. Cáceres-Aravena, L. E. F. Foa Torres, and R. A. Vicencio, Physical Review A 102, 023505 (2020).publisher arXiv:2004.11932

Introduction to Graphene-Based Nanomaterials: From Electronic Structure to Quantum Transport — Second edition

Quantum Pumping

Mon, 03 Aug 2020 00:00:00 +0000

(or how to generate a current at zero bias)

A direct current (dc) is usually associated to a dissipative flow of the electrons in response to an applied bias voltage. However, in systems of mesoscopic scale a dc current can be generated even at zero bias. This captivating quantum coherent effect is called quantum pumping* *(*quantum charge pumping *to be more precise). A device capable of providing such effect is called a quantum pump [1] .

Research

Mon, 03 Aug 2020 00:00:00 +0000

I’m a condensed matter physicist with over 15 years of experience in the field of quantum transport, modeling and simulation of nanomaterials and nanodevices. After working in Italy, France and Germany and Argentina, I joined the Department of Physics (FCFM) of the University of Chile. Here I lead an interdisciplinary team (physicists and chemists) working on the electronic and optoelectronic properties of nanomaterials and nanodevices.

Most of my research is focused on the electrical (quantum transport) and opto-electronic properties of two dimensional nanomaterials (graphene-based, TMDCs) and topological insulators, driven and non-hermitian systems. In particular, my efforts are aimed to the understanding and control of quantum effects arising from time-dependent fields, many-body interactions and decoherence. At the moment the questions that fuel my attention have to do with new phases of (non-equilibrium) topological insulators. The idea behind one of them is generating and tuning topologically protected states by using a laser field. Another research line is the search for topological states in non-Hermitian systems.

SASER (phonon laser)

Mon, 03 Aug 2020 00:00:00 +0000

Sasers, the sonic equivalent of lasers, are today the center of fascinating investigations which, besides their promising technological applications, may help to unveil fundamental issues on coherence and spontaneous order. SASER is the acronym for Sound Amplification by Stimulated Emission of Radiation. The main function of a *saser or phonon laser *is to produce a highly coherent beam of ultrasound. As we emphasize below, sasers are of much current fundamental and technological interest. My contribution to this field was done within the context of a long time collaboration between the groups of Sergio Makler (Rio de Janeiro, Brazil) and Horacio Pastawski (Cordoba, Argentina) [1,2], we proposed [3,4] an alternative scheme for the generation of terahertz phonons in a double barrier resonant tunneling device. The essential idea is to transform the kinetic energy that the electrons acquire from an applied electric field into lattice vibrations (phonons).

Teaching

Mon, 03 Aug 2020 00:00:00 +0000

I have taught courses in Physics, Mathematics and Materials Science to students across different disciplines in four countries (Argentina, France, Germany and Chile).

These courses include: Solid State Physics, Modern Physics, Quantum Transport and Quantum Mechanics.

I started teaching during the last year of my Physics degree, back in 1999. Since then I have accumulated teaching experience at both graduate and undergraduate levels in Argentina, France, Germany and Chile. At the undergraduate level I taught Physics, Mathematics and Materials Science to a broad spectrum of students in Physics, Chemistry, Materials Science, Computer Science and Engineering. At the graduate level, I taught solid state physics, quantum transport and molecular electronics to graduate and advanced students of Physics and Chemistry.

Team

Mon, 03 Aug 2020 00:00:00 +0000

Our focus is on Topological Quantum Matter and driven systems. Our test ground are mostly two-dimensional materials and topological insulators.

Following my appointment at the University of Chile in 2016, the present team is a continuation of Nanocarbon@FaMAF, our earlier workgroup at the University of Córdoba (FAMAF-UNC, Argentina), which was active between 2009 and 2015.

Luis E. F. Foa Torres.
Diego Bautista Avilés (Doctoral Fellow ANID)
Julián Faúndez (external Postdoctoral Fellow FONDECYT)
Frida Fernanda García López (Doctoral Fellow EPEC)
Claudia San Martín (Magister student)

Former members

Contact

Mon, 13 Jul 2020 00:05:55 +0000

Send me an email to

luisfoa at gmail.com

or find me in LinkedIn.

Present Address:

Departamento de Física, Universidad de Chile

Blanco Encalada 2008,

Santiago, RM, Chile

Where is this? Right in the red spot, my office is in the third floor, West side.

Perspective on topological states of non-Hermitian lattices

Tue, 01 Jan 2019 00:00:00 +0000

Luis E F Foa Torres

Journal of Physics: Materials 3, 014002 (2020)

doi:10.1088/2515-7639/ab4092

Free access article

Abstract

The search of topological states in non-Hermitian systems has gained a strong momentum over the last two years climbing to the level of an emergent research front. In this perspective we give an overview with a focus on connecting this topic to others like Floquet systems. Furthermore, using a simple scattering picture we discuss an interpretation of concepts like the Hamiltonian’s defectiveness, i.e. the lack of a full basis of eigenstates, crucial in many discussions of topological phases of non-Hermitian Hamiltonians.

The non-hermitian skin effect and topological states of non-Hermitian systems

Fri, 25 Aug 2017 00:00:00 +0000

The coalesce of the states at a higher-order exceptional point leads to the non-Hermitian skin effect. In contrast with usual exceptional points, at this Aleph of exceptional points a number of states scaling with the system size coalesce. The image features the original cover of the book El Aleph by Borges together with a drawing from Ref. 3.

The non-Hermitian skin effect (NHSE) is a remarkable phenomenon where, contrary to conventional wisdom, a vast number of a system’s states-often all of them-become localized at its boundaries [1, 2]. This effect fundamentally challenges the textbook bulk-boundary correspondence and has become a sensational discovery in physics, with profound implications for photonics, acoustics, and quantum systems.

Introducción a la Teoría de Sólidos 2010

Sun, 01 Aug 2010 00:00:00 +0000

Bienvenidos!

Esta es una colección de algunos links y recursos útiles para la materia. Las sugerencias o comentarios son bienvenidos!

Horario: Lunes 15-17 hs (Aula 26) y Jueves 14:30-17 hs (Aula 23).

Programa detallado y bibliografía recomendada.

Referencias

[1] Ashcroft and Mermin, “Solid State Physics”, ISBN: 0-03-083993-9.

[2] Ziman, “Principles of the theory of solids”, ISBN: 978-0521297332.

[3] Peierls, “Surprises in theoretical physics”, ISBN: 978-0691082424; “More surprises in theoretical physics”, ISBN: 978-0691025223.

Mecánica Cuántica 1 – 2010

Sun, 01 Aug 2010 00:00:00 +0000

Bienvenidos!

Esta es una colección de algunos links y recursos útiles para la materia. Las sugerencias o comentarios son bienvenidos!

La Mecánica Cuántica es hoy la teoría más probada y exitosa que jamás haya existido. Es probablemente, sin embargo, una de las más anti-intuitivas.

Una herramienta muy poderosa para ganar intuición en los intrincados caminos de esta teoría es la utilización de ordenadores. Visualizar los resultados puede ser una de las actividades más valiosas y enriquecedoras.

PhD Thesis Abstract

Sun, 01 Aug 2004 00:00:00 +0000

PhD Thesis: “On the effects of the many-body interactions and decoherence in the conductance of nano-devices” (Original title:(Spanish) “Sobre los efectos de la decoherencia y las interacciones de muchos cuerpos en la conductividad de nanodispositivos”)

by Luis E. F. Foà Torres

(born in Córdoba in 1978) Presented to the Facultad de Matemáticas, Astronomía y Física, Universidad Nacional de Córdoba, Argentina (School of Mathematics, Astronomy and Physics of the Córdoba National University, Argentina) in partial fulfillment of the requirements for the degree of Doctor in Physics. Advisor: Prof. Dr. Horacio M. Pastawski Córdoba, Argentina, August 2004