Andrea Maiani

WINQ Postdoctoral fellow, Nordita.

Impurity States in Altermagnetic Superconductors

When: 12:00-13:00 CET, November 26th (Tuesday), 2024

Where: Sala de Seminarios (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

Altermagnets are a novel class of magnetic materials distinct from ferromagnets and antiferromagnets, characterized by vanishing net magnetization and unique spin-split band structures – appealing features for exotic quantum phenomena and spintronics applications. This talk explores the interplay between altermagnetism and superconductivity, focusing on how impurities can serve as local probes of altermagnetic superconductors. I will briefly introduce altermagnetic materials, their interplay with superconductivity, and review the basic theory of impurity states in superconductors. I will then present our original theoretical work on the role of impurities in altermagnetic superconductors, predicting the emergence of spin-polarized subgap states that extend along the crystal axes. These states form degenerate doublets, which can be split by crystal symmetry breaking or a magnetic field aligned with the Néel vector. Their unique spatial and spin properties provide measurable signatures via scanning tunneling microscopy, serving as a hallmark for altermagnetic superconductivity. Finally, I will discuss the interaction between impurities, revealing a position-dependent, spin-selective coupling that enables in-situ control of devices crucial for quantum information processing and topological superconductivity.

Natalia Berloff

Department of Applied Mathematics and Theoretical Physic, University of Cambridge, UK

Non-Hermitian Gain-Based Computing with Coupled Light-Matter Systems 

When: 12:00-13:00 CET, November 7th (Thursday), 2024

Where: Sala de Seminarios (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

Valeria Ferrari

Departamento de Física de la Materia Condensada, Comisión Nacional de Energía Atómica (CNEA). Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Nanociencia y Nanotecnologia (CNEA-CONICET)

Radiation Effects at Oxide-Water Interfaces: Current Insights and Future steps 

When: 12:00-13:00 CET, October 31th (Thursday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

The interaction between ionizing radiation and oxide-water interfaces is a key topic in material science research in the quest for materials with technological applications, such as nuclear waste management, metal corrosion in aqueous environments, and biological systems exposed to radiation. This talk will explore atomic-level processes occurring at these interfaces, with particular emphasis on hydrogen generation in oxides such as zirconia and copper oxide, both of which are used in nuclear facilities.

The current challenges in understanding the mechanisms behind these processes through electronic structure methodologies will be discussed, including density functional theory (DFT) and many-body perturbation theory (MBPT) approaches, such as the GW approximation and the Bethe-Salpeter equation (BSE). Our preliminary results in these materials, focusing on excitonic properties and radiation-induced processes, will also be presented.

This work is part of the Horizon project titled “Materials Radiation: From Basics to Applications” (MAMBA), which aims to deepen the understanding of material responses to irradiation and apply this knowledge to tailor and control the properties of materials exposed—either intentionally or unintentionally—to intense radiation environments. Finally, the talk will outline the future steps in this research, including modeling different oxide facets, analyzing excitonic wave functions, and using machine learning to describe the corresponding oxide-water interfaces.

Manhong Yung

Southern University of Science and Technology, China

From quantum inspired to quantum speedup

When: 12:00-13:00 CET, October 17th (Thursday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

Quantum computing has reached a critical moment. On the one hand, quantum hardware are continuously advancing. On the other hand, quantum computational advantage over classical computing has not yet been available for practical problems. Moreover, the road to universal quantum computing is still long. The highly anticipated quantum variational algorithm is still constrained by a small number of qubits and shallow circuits. Some scholars even think that “NISQ is dead”. In this talk, based on the applications of quantum-inspired algorithms, we introduce the concept of quantum acceleration algorithms and discuss how NISQ quantum hardware can act as an accelerator and add to the value of quantum computing through the mixture with classical computing.

Fernando Martín

Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain

Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nano), 28049 Madrid, Spain

Attochemistry: chemistry at the attosecond time scale

When: 12:00-13:00 CET, October 10th (Thursday), 2024

Where: Salón de Actos, ICMM-CSIC, Campus de Cantoblanco, Madrid

With the advent of attosecond light pulses at the dawn of the twenty first century, access to the time scale of electronic motion, i.e., the ultimate time scale responsible for chemical transformations, was finally at our reach. Since the first attosecond pump-probe experiments performed in molecules [1,2], the field has grown exponentially, leading to a discipline that we call attochemistry [3]. As a result, it is nowadays possible to follow in real time the motion of the “fast” electronic motion in molecules, mostly in the gas phase, and understand how this motion affects the “slower” motion of atomic nuclei and vice versa. There are, however, new scenarios [4] that will allow one to extend the range of applications to more complex molecular systems, including the condensed phase, and to overcome some of the limitations of current attosecond technologies [5-9], such as the low intensity of attosecond pulses produced by high harmonic generation, the impossibility to generate such pulses in the visible and UV spectral regions to avoid molecular ionization, or the difficulties to combine them with truly imaging methods as those used in condensed matter physics for direct time-resolved observations of the electron density without the need for reconstruction from measured photoelectron, photoion or transient absorption spectra.

In this talk, I will describe current experimental and theoretical efforts aiming at overcoming the above-mentioned limitations, thus giving attochemistry the necessary push to investigate problems of real chemical interest.

References:
[1]  G. Sansone, F. Kelkensberg, J. F. Pérez-Torres, F. Morales, M. F. Kling, W. Siu, O. Ghafur, P. Johnsson, M. Swoboda, E. Benedetti, F. Ferrari, F. Lépine, J. L. Sanz-Vicario, S. Zherebtsov, I. Znakovskaya, A. L’Huillier, M. Yu. Ivanov, M. Nisoli, F. Martín, and M. J. J. Vrakking, Nature 465 763 (2010).

[2] F. Calegari, D. Ayuso, A. Trabattoni, L. Belshaw, S. De Camillis, S. Anumula, F. Frassetto, L. Poletto, A. Palacios, P. Decleva, J. B. Greenwood, F. Martín, and M. Nisoli, Science 346, 336 (2014).

[3] M. Nisoli, P. Decleva, F. Callegari, A. Palacios, and F. Martín, Chem. Rev. 117, 10760 (2017).

[4] F. Calegari and F. Martín, Commun. Chem. 6, 184 (2023).

[5] A. Palacios and F. Martín, WIREs Comput. Mol. Sci. e1430 (2020).

[6] G. Grell, Z. Guo, T. Driver, P. Decleva, E. Plésiat, A. Picón, J. González-Vázquez, P. Walter, J. P. Marangos, J. P. Cryan, A. Marinelli, A. Palacios, and F. Martín, Phys. Rev. Res. 5, 023092 (2023).

[7] M. Galli et al, Optics Letters 44, 1308 (2019).

[8] M. Reduzzi et al, Optics Express 31, 26854 (2023).

[9] M. Garg, A. Martín-Jiménez, M. Pisarra, Y. Luo, F. Martín and K. Kern, Nature Photonics 16, 196 (2022).

[10]  F. Vismarra, F. Fernández-Villoria, D. Mocci, J. González-Vázquez, Y. Wu, L. Colaizzi, F. Holzmeier, J. Delgado, J. Santos, L. Bañares, L. Carlini, M. Castrovilli, P. Bolognesi, R. Richter, L. Avaldi, A. Palacios, M. Lucchini, M. Reduzzi, R. Borrego- Varillas, N. Martín, F. Martín, and M. Nisoli, Nature Chemistry in press.

Peter Kraus

Vrije Universiteit (VU) Amsterdam, Advanced Research Center for Nanolithography (ARCNL), Netherlands

Towards ultrafast imaging of correlated matter with transient high-harmonic generation

When: 12:00-13:00 CET, October 1st (Tuesday), 2024

Where: Main Hall, ICMM-CSIC, Campus de Cantoblanco, Madrid

The highly complex collective electron-dynamics in strongly correlated materials mandates experimental techniques with sub-fs temporal and nanometer spatial resolution. While a plethora of techniques exists, true nanometer imaging on fs or even sub-fs timescales remains elusive. Such techniques are required to follow the collective dynamics of electrons in strongly correlated materials in real time, which drive ultrafast phase transitions that are accompanied by technologically relevant order-of-magnitude resistivity switches.
High-harmonic generation (HHG) in solids has emerged 14 years ago. Gas-phase HHG is highly sensitive and thus optically controllable with regards to the microscopic generation
mechanism. The parallels between solid and gas-phase HHG suggest that solid-state HHG may be controlled in a similar manner, which enables a generally applicable all-optical light switch with wide application potential. The current literature on transient solid-state HHG confirms this opportunity of all-optical control of solid HHG [1]. In this talk, I will present our vision to use this light switch for sub-fs super-resolution nanoscale imaging by HHG from correlated materials. In particular, I will present three key experiments on our roadmap towards this goal.
On the nanoscale, we controlled HHG via engineering the surface topography of solids, which in turn demonstrates how solid HHG can be used for metrology on surfaces and tailored as a light source [2-4].
On the femtosecond time scale, we used the sensitivity of HHG to electronic band structure to follow ultrafast phase transitions in strongly correlated materials [5], and photocarrier dynamics in perovskites [6]. While the first measurements [2] showed nanoscale sensitivity, the second set of experiments [5,6] demonstrated that photoexcitation can be used to control light emission via solid HHG.
Combining both efforts, I will show first results how ultrafast control of solid HHG enables
HArmonic DEactivation microScopy (HADES) – a label-free super-resolution microscopy
below the diffraction limit of light [7]. Thinking ahead, the development of these techniques may enable resolution on the nanometer and femto- to attosecond scale fitted into a regular microscopy setting, with application potential ranging from strongly correlated materials to semiconductor metrology, photosynthetic processes, and medical imaging.

References:
[1] P. v. Essen, Z. Nie, B. de Keijzer, P.M. Kraus, arXiv:2402.15375, ACS Photonics, accepted  (2024).
[2] S.D.C. Roscam Abbing, R. Kolkowski, Z.-Y. Zhang, F. Campi, L. Loetgering, A.F. Koenderink, P.M. Kraus,
Physical Review Letters 128, 223902 (2022).
[3] P. M. Kraus et al., US Patent App. 18/038,590 (2024).
[4] P. M. Kraus et al., US Patent App. 18/253,734 (2024).
[5] Z. Nie et al., Peter M. Kraus, Physical Review Letters, 131, 243201 (2023).
[6] M. v.d. Geest, J.J. de Boer, K. Murzyn, P. Juergens, B. Ehrler, P.M. Kraus, Journal of Phys. Chem. Lett., 14, 10810 (2023).
[7] K. Murzyn, M.v.d. Geest, L. Guery, Z. Nie, P.v. Essen, S. Witte, P.M. Kraus, arXiv:2403.06617, submitted (2024).

Miguel Bastarrachea-Magnani

Universidad Autónoma
Metropolitana-Iztapalapa

Quantum probing of classical structures in the Dicke Hamiltonian

When: 12:00-13:00 CET, November 21st (Thursday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

The Dicke Hamiltonian is a paradigmatic model of quantum
optics that describe the ultra-strong coupling between light and
collective modes of matter. This interaction results in the creation of
polaritons, hybrid quantum states that share properties of their
original components. Originally proposed to describe atoms in cavities,
the model has now become a general formulation of the spin-boson
interaction with applications in polariton physics and various systems
within the context of quantum information, atomic physics, and condensed
matter. In this talk, I will address the model’s theoretical richness
for exploring the quantum-classical correspondence. Thanks to its
collective nature, it is possible to easily identify a classical
counterpart and use quantum localization techniques to probe, identify,
and quantify structures in phase space, regularity, and chaos,
establishing a route to explore other, more complex, interacting quantum
systems.

Gerhard Klimeck

Purdue University, West Lafayette, IN 47907, USA

From Atomistic, Non-Equilibrium Quantum Statistical Mechanics Theory
to Today’s Transistor Design and Global Impact – A 25-Year Journey

When: 11:00-12:00 CET, September 18th (Wednesday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

30 years ago, the appropriate quantum transport theories, basis sets, algorithms, user interfaces, and dissemination methods for quantum device modeling were subjects of intense debate and uncertainty. The development of the Nanoelectronic MOdeling (NEMO) toolset commenced in 1994 at Texas Instruments, continued in 1998 and NASA/JPL, and has been ongoing at Purdue since 2004. Modern nanoscale transistor design extensively employs advanced quantum transport modeling tools, representing physical devices in three dimensions with atomistic basis sets. The NEMO implementations of the Non-Equilibrium Green Function (NEGF) formalism with atomistic tight-binding basis have become the benchmark for quantitative and predictive device simulation. This methodology has now been widely adopted by most device modeling research teams. In 2015, Intel integrated NEMO5 into their in-house design suite, utilizing a top-100 ranked supercomputer for design explorations [1]. Silvaco initiated commercialization efforts [2] in 2018, with industry leaders such as Samsung and TSMC developing their in-house solutions based on NEMO. NEMO’s capability to accurately model crystal orientations and strain in complex systems facilitated the development of Texas Instruments’ rotated substrate technology in 2004 [3], significantly impacting chips used in billions of cell phones. Contemporary 3D FinFETs [4] and nanosheet transistors share the 5 nm central length characteristics with 1D resonant tunneling diodes (RTDs). The quantitative and predictive modeling of 1D RTDs (1994-1997) established the standards necessary for today’s 3D nano-transistors.

NEMO’s applications extend beyond usage by experts equipped with specialized computational hardware. Over 25,000 users on nanoHUB.org, the pioneering comprehensive scientific computing cloud platform, have investigated various nanoscale devices such as nanowires, ultra-thin-body transistors, and quantum dots utilizing the intuitive NEMO/OMEN tools. These tools are supplemented by straightforward applications, rendering them accessible to a broad spectrum of users. Notably, more than fifty percent of nanoHUB’s simulation users participate in formal educational settings across 1,000 institutions globally, immersing themselves in device exploration and modeling principles. nanoHUB hosts 700+ apps and tools, along with over 170 courses.

This presentation will provide an overview of the critical physical phenomena needed to be captured for realistic device design, how high-performance-computing can deliver results to engineers & students, and how NEMO has been deployed on nanoHUB.org.

This work would not have been possible without my hundreds of collaborators who helped to build, test drive, break, and rebuild NEMO/OMEN [5-9,12-14] and nanoHUB [10,11].  I have the deepest appreciation for their hard work, dedication and in most cases their personal friendship. The citations here just cover some of the fundamental developments. Citations to these papers lead to hundreds of publications enabled by my collaborators and friends.

[1] Mark Stettler et al., IEDM, 39.1.1 (2019)
[2] Silvaco – Victory Atomistic, silvaco.com
[3] RC Bowen et al., US patent 7,268,399 (2004)
[4] G. Yeap et al., IEDM, 36.7.1 (2019)
[5] G. Klimeck, et al., APL Lett. 67, 2539 (1995)
[6] RC Bowen, et al., JAP 81, 3207 (1997)
[7] Jing Wang, et al., APL. 86, 093113 (2005)
[8] M Luisier, et al., Phys. Rev. B 74, 205323 (2006)
[9] G Klimeck el al, Superlatt. and Microstr., 27, 77, (2000)
[10] G Klimeck, et al, IEEE CISE, Vol. 10, 17 (2008)
[11] M. Hunt et al, PLoS ONE 17(3): e0264492.
[12] R Lake, et al.,JAP 81, 7845 (1997)
[13] G. Klimeck, et al, Computer Modeling in Engineering and Science (CMES) 3, 601-642 (2002).
[14] S Steiger et al., IEEE Tr. Nanotechn., 10, 1464, (2011)

Elton J. G. Santos

Higgs Centre for Theoretical Physics, Institute for Condensed Matter and Complex Systems – School of Physics and Astronomy, The University of Edinburgh, UK

 Exploring the Limits of Ultrafast Magnetism in Quantum Materials 

When: 12:00-13:00 CET, June 5th (Wednesday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

 Long searched but only now discovered two-dimensional (2D) magnets are one of the selected group of materials that retain or impart strongly spin correlated properties at the limit of atomic layer thickness. In this presentation, I will discuss how different layered compounds (e.g., CrX3 (X=F, Cl, Br, I), MnPS3, Fe5-xGeTe2, Cr2Ge2Te6) can provide new playgrounds for applications and fundamental exploration of spin correlations involving quantum-effects, topological spin-excitations and ultrafast laser pulses. In particular, I will show how van der Waals magnets do not require any magnetic anisotropy to stabilize 2D magnetism and demonstrate the null valid of the Mermin-Wagner theorem in practical applications. Moreover, some recent results of ultrafast laser excitations on different vdW heterostructures will be shown towards all-optical control of their magnetic properties with efficient heat management. 

Johannes Feist

Department of Theoretical Condensed Matter Physics, Universidad Autonoma de Madrid, Spain

Using cavities to modify material properties

When: 12:00-13:00 CET, May 23th (Thursday), 2024

Where: Seminar Room (182), ICMM-CSIC, Campus de Cantoblanco, Madrid

The use of cavity quantum electrodynamical effects, i.e., of vacuum electromagnetic fields, to modify material properties has rapidly gained popularity and interest in the last decade. A canonical example of this is strong light-matter coupling, reached when the interaction of material excitations with confined light modes overcomes dissipation effects and the two parts hybridize to form mixed light-matter eigenstates, so-called polaritons. These polaritons inherit properties of both light and matter excitations and additionally display fundamentally new phenomena. The large range of possible material systems and cavity architectures opens a rich playground for novel functionalities. In the talk, I will discuss several topics related to this overall field, including the modification and photophysics and photochemistry in organic molecules, some fundamental results and pitfalls for the modification of low-energy excitations, and recent progress on few-mode field quantization in complex nanophotonic structures, i.e., strategies to obtain the construction of cavity-QED-like models for arbitrary cavity geometries and materials.