Families of isomers of astrochemical significance

Marcin Gronowski (Institute of Physical Chemistry, Polish Academy of Sciences)
Date & location:  Tue 5 Dec  2017 12:30:00 GMT+0200 (CEST), Conference Room, Serrano 121 (CFMAC)

Abstract: Around one-third of all confirmed interstellar molecules observed also had at least one other observable isomer. The interstellar formation of various family members might involve isolated,  gas-phase molecules or molecules on the surface of or incorporated
within ice and dust particles. Once formed, disparate structural isomers add complexity to astrochemical models.

Within a given family of structural isomers, it is still an open question as to which members might reasonably be expected to be found  in  space  and  therefore  should  be  considered  as high priority  in astro-spectroscopic  investigations or  in  laboratory

We  applied  a  range  quantum  chemical  methods  to  characterize isomers  of  following  stoichiometry:  CHMgN,  C2HNO,  C4H3N, C3H3N, C2H3NS, and CH2NS+. Thermodynamic and kinetic stability, as well as a possibility of detection by microwave spectroscopy, were discussed. We proposed potential synthetic pathways of CH2NS+ isomers in cold, dense nonturbulent interstellar clouds (like TMC-1). Some of the isomers with C3H3N, C2H3NS stoichiometry were photochemically generated and characterized in a noble gas matrix.

Linear-scaling DFT calculations for materials and biomolecules: a selection of recent applications

Chris-Kriton Skylaris (University of Southampton)
Date & location:  Mon 20 Nov  2017 16:00:00 GMT+0200 (CEST), Conference Room, Serrano 121 (CFMAC)

First-principles quantum mechanical calculations based on Density Functional Theory (DFT) are free of empirical parameters  and  can  thus provide  a  very  accurate  description  of  properties  and  processes  of  materials  and molecules. However, the computational effort of conventional DFT scales with the third power in the number of atoms and limits the size of the calculations to no more than a few hundred atoms.

To perform DFT calculations with  thousands  of  atoms  and  enable  the  study  of  complex  materials  we  have  developed  the  ONETEP  program which is based on a linear-scaling reformulation of DFT in a way that retains the same high level of accuracy as conventional cubic-scaling methods. I will provide an outline of the ONETEP program and its current capabilities followed by examples of applications ranging from materials and nanoparticles to entire proteins.

K. Skylaris, P. D. Haynes,A. A. Mostofi and M. C. Payne. J. Chem. Phys. 122(2005) 084119.
M.J.S. Phipps, T. Fox, C.S. Tautermann and C.-K. Skylaris. J. Chem. Theory Comput. 13 (2017) 1837.
J. Aarons, L. Jones, A. Varambhia, K. E. MacArthur, D. Ozkaya, M. Sarwar, C.-K. Skylaris, and P. D. Nellist. Nano Lett. 17 (2017) 4003


Quantum reflection

Salvador Miret Artés (IFF, CSIC)
Date & location:  Thu 26 Oct  2017 12:00:00 GMT+0200 (CEST), Conference Room, Serrano 121 (CFMAC)

Abstract: Quantum reflection refers to the classically forbidden reflection of a particle in a classically allowed region without classical turning points, and can take place in the attractive regions of atom-atom and atom-surface interaction potential at near-threshold energy conditions. The nonclassical region of the potential or badlands region is typically located at distances of several hundreds or even thousands of atomic units, where the potentials are well described by van der Waals forces with retardation effects (Casimir-van der Waals tails). In this talk, we analyze experimental quantum reflection probabilities in the scattering/diffraction of several particles (He, Ne, He2,…) by a micro-structured grating at grazing angles and very low incident energies.

Pumping and probing vibrational modulated electronic coherence by quantum dynamics

Stephan van den Wildenberg (University of Liége)
Date & location:  Wed 11 Oct  2017 12:30:00 GMT+0200 (CEST), Meeting Room, Serrano 113-bis (CFMAC)

Electronic excitation of molecules using few femtoseconds or attoseconds optical pulses can build coherentsuperpositions of electronic states. A coherent superposition of electronic typically corresponds to a non-stationary electronic density that moves before the onset of nuclear motion, on the few femtosecond or attosecond timescale. By controlling the parameters of the exciting pulse, it is possible to tailor the non-stationary electron density induced by this pulse. In longer timescale, nuclear motion takes place, and this motion is coupled with the motion of the non-stationary electron density, which opens a way toward control of nuclear dynamics. To achieve this objective, one has to understand how does nuclear motion influences the evolution of the non-stationary electron density by computing the coupled dynamics of electrons and nuclei.In this seminar, I will discuss the coupled electronic-nuclear coherent dynamics induced by a short strong VUV fs pulse in the low lying excited electronic states of HCN probed by transient absorption spectroscopy with a second weaker fs UV pulse.

Ultrastrong coupling regime of two-photon interactions

Simone Felicetti (Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Diderot.)
Date & location:   Mon 9 Oct  2017 12:00:00 GMT+0200 (CEST), Confrence Room, Serrano 121 (CFMAC)

Abstract: Two-photon processes have so far been considered only as effective models to describe
quantum optical systems subjected to strong classical drivings. In this case, two-
photon interactions (TPI) arise from second- or higher-order effects, and so they are
limited to extremely small coupling strengths. However, a variety of novel physical
phenomena emerges in the strong or ultrastrong coupling regime, where such
coupling values become comparable to dissipation rates or to the system bare
frequencies, respectively. For instance, in the ultrastrong coupling regime of TPI a
spectral collapse [1] can take place, i.e. the system discrete spectrum can collapse in a
continuous band.

In this talk, I will present different schemes to implement TPI using current quantum
technologies and recent theoretical analysis on the physics of such models. First, we
designed a quantum-simulation protocol [2,3] where a trapped-ion system is used to
implement ultrastrong TPI between a chain of qubits and a single bosonic mode. We
analyzed the many-body limit of this system, revealing a rich interplay between the
spectral collapse and the superradiant phase transition [4]. Then, we designed a
superconducting circuit scheme to implement genuine TPI in a solid-state device [5].
An open quantum system analysis shows that fundamental quantum optical
phenomena are qualitatively modified with respect to standard dipolar interactions.
We find that realistic parameters allow to reach the spectral collapse, where extreme
nonlinearities are expected to emerge at the few-photon level.

1. I. Travěnec, Phys. Rev. A 85, 043805 (2012).
2. S. Felicetti, J. S. Pedernales, I. L. Egusquiza, G. Romero, L. Lamata, D. Braak, and E. Solano, Phys. Rev. A 92, 033817 (2015).
3. L. Puebla, M. Hwang, J. Casanova, M. Plenio, Phys. Rev. A 95, 063844 (2017).
4. L. Garbe, I. L. Egusquiza, E. Solano, C. Ciuti, T. Coudreau, P. Milman, S. Felicetti, Phys. Rev. A 95, 053854 (2017).
5. S. Felicetti, D. Z. Rossatto, E. Rico, E. Solano, and P. Forn-Díaz, in preparation (2017).

Interacciones no covalentes entre el cisplatino y prototipos de grafeno

María del Refugio Cuevas Flores (IFF, CSIC)
Date & location:  Tue 20 Jun  2017 12:00:00 GMT+0200 (CEST), Meeting Room, Serrano 113-bis (CFMAC)

El cisplatino(CP) es un fármaco anti-cáncer ampliamente utilizado desde hace más de 30 años, no obstante sus efectos secundarios adversos asociados a su baja biocompatibilidad y mala especificidad. Por otro lado, últimamente se han desarrollado de manera importante el estudio y diseño de nuevos nanomateriales que permiten trasportar de manera eficiente especies moleculares a blancos biológicos. Por ejemplo el Grafeno (G) y sus derivados han mostrado la capacidad de adsorber eficientemente diversas sustancias biológicas como fármacos, anticuerpos, péptidos, DNA, RNA o genes mediante interacciones no covalentes.  La geometría cuadrado plana del CP aunada a su baja solubilidad, sugiere que podría ser un buen candidato para adsorberse físicamente en nanomateriales 2D como el G, mediante la interacción con un sistema p altamente conjugado.

En este trabajo hemos seleccionado al pireno (P) como el prototipo mínimo de G que nos permita de manera eficiente y precisa estudiar las interacciones no covalentes involucradas en la adsorción física del CP. En particular, cálculos de estructura electrónica mediante los métodos “Coupled Second order Möller-Plesset Perturbation Theory (MP2C) y “Density Functinal Theory-Symmetry Adapted (DFT-SAPT) nos permitieron obtener  energías de interacción de referencia para el complejo CP-P así como las distintas  contribuciones a la energía de interacción total. Se encontró que las configuraciones paralelas son las más estables, debido principalmente a la contribución de dispersión y este comportamiento se asemeja a lo de complejos enlazados mediante interacciones de tipo p-p .

Las energías de interacción de referencia nos permitieron validar la energía calculada mediante diferentes aproximaciones de la DFT (con correcciones de dispersión), que son más asequibles para calcular la interacción del CP con prototipos de grafeno de mayor tamaño. Una vez validado un funcional óptimo se utilizó para el cálculo de la energía de interacción del CP con prototipos que van desde el coroneno(C24H12) y ovaleno(C32H14) hasta  C150H30.

La optimización de la geometría y el relativo cálculo de frecuencias, junto con una extrapolación adecuada permitieron estimar la entalpía de adsorción del CP en G a 298 K y 1 bar, obteniendo un valor particularmente favorable (alrededor de -20 kcal-mol-1) siendo prácticamente el doble del estimado en la correspondiente adsorción del benceno.

Non-ergodicity in many body systems and disordered random graphs; application to the phase diagram Josephson junction chain.

Lev B. Ioffe (CNRS/Universite Paris Sud)
Date & location:   Tue 13 Jun  2017 12:00:00 GMT+0200 (CEST), Meeting Room, Serrano 113-bis (CFMAC)

Abstract: At very high disorder a generic closed quantum system becomes completely localized. I argue that this (many body) localization is preempted by a wide regime of non-ergodic behavior that displays a number of unusual properties. A good system to study these effects are Josephson junction arrays in a somewhat unusual regime. In the main part of the talk I will discuss the localization of single particles on random regular graphs that provide a toy model capturing the main physics of the many body localization. I will develop a simplified analytical theory of the non-ergodic phase in this models that extends the approach developed in the work of Abou Chakra, Thouless and Anderson and compare the results with the direct numerical simulations.

Quantum Simulator of the factorization problem

José Lus Rosales (UPM)
Date & location:   Fri 12 May  2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: We revisit the analytic number theory of  factoring numbers N=xy, product of two primes, in order to build a new  approach suitable for statistical analysis. This is readily translated to the physics of a system in two dimensions with bound trajectories. After semiclassical quantization we get that the statistics of the energies for these trajectories lead to the statistics of the primes pi (x) < pi ( sqrt N).  The result  is fully equivalent to obtaining the prime factors of  N from  the quantum theory of this simulator  in a way entirely  alternative to Shor’s algorithm.
Finally we advance the result that this quantum system can be experimentally implemented and show our proposal for the experimental setup.

Multifractal metal in a disordered Josephson Junctions Array

Manuel Pino (IFF,CSIC)
Date & location:   Fri 05 May  2017 12:00:00 GMT+0200 (CEST), Meeting Room, Serrano 113-bis (CFMAC)

Abstract: We show that quantum chaotic dynamic may not result in thermalization in certain bosonic models that can be realized as an array of Josephson junctions. This model exhibits a many-body localization transition which separates insulating and metallic phases. Localization prevents the system to thermalize in the insulating phase. We show that there is a intermediate region in the phase diagram, between Many-Body localized and ergodic phases, in which the system behaves as a metal but it is not described by the laws of Statistical Mechanics.

Probing quantum correlations with multiple atomic impurities

Jordi Mur-Petit (Clarendon Laboratory, University of Oxford)
Date & location:  Thu 04 May  2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Experimental advances in the control and measurement of quantum systems are driving the development of quantum technologies across multiple experimental platforms, from trapped ions and cold atoms, to superconducting circuits and nanomechanical setups [1]. Among the most promising practical applications of these devices lies quantum-enhanced sensing, where individual or quantum-correlated particles are used to accurately measure observables, from magnetic fields to gravity. Extending this paradigm, recent work has highlighted the potential of single quantum systems to probe strongly-correlated quantum systems [2].

In this talk, I will present a quantum protocol that uses multiple atomic impurities to measure N-point correlations in strongly-correlated quantum systems [3], and discuss ongoing experimental efforts at Oxford to implement it with a two-species cold-atom setup [4].

[1] G. Kurizki et al., PNAS 110, 3866-3873 (2014); K. Bongs et al., Proc. SPIE 9900, 990009 (2016).
[2] See, e.g., D. Hangleiter et al., Phys. Rev. A 91, 013611 (2015); T.H. Johnson et al., Phys. Rev. A 93, 053619 (2016).
[3] M. Streif, A. Buchleitner, D. Jaksch & J. Mur-Petit, Phys. Rev. A 94, 053634 (2016).
[4] E. Bentine et al., J. Phys. B 50 094002 (2017).

Huygens principle and Dirac equation

Saverio Pascazio (Universita di Bari/INFN)
Date & location:  Tue Apr 25 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Every point on the wave front of a propagating wave is a source of secondary wavelets, which spread forward at the same speed as the source wave. The wave front at later times is then given by the surface tangent to the secondary wavelets.  This principle was proposed by Christiaan Huygens in 1678, to explain the laws of reflection and refraction. It was used again more than a century later, in 1816, by Augustin-Jean Fresnel, to intepret the diffraction effects that occur when visible light encounters slits, edges and screens.

The principle provides crucial insight into the nature of wave propagation and it is a milestone in the physics of ondulatory phenomena. For this reason, its universal validity is usually taken for granted. However, yet one century later, Jacques Hadamard noticed that Huygens’ principle is valid only when waves propagate in an odd number n>1 of spatial dimensions.

Both quantum mechanics and quantum field theory make use of wave equations in their formulation. It is therefore interesting to ask whether Huygens’ principle holds for the seminal equations that are the backbone of these theories. The Schrodinger equation, being non-relativistic, does not admit a satisfactory formulation of this question. What about the Dirac equation?

We discuss the validity of Huygens’ principle for the massless Dirac-Weyl equation. We find that the principle holds for odd space dimension n, while it is invalid for even n. We explicitly discuss the cases n=1,2 and 3.

New insights into metallic nanoparticles for enhancement of particle therapy in hypoxic tumors

Marta Bolsa (Institut des Sciences Moléculaires d’Orsay, CNRS)
Date & location:  Wed Apr 19 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Low oxygen concentration in tumors results in lower cell death after exposure to radiation. The oxygen effect is expressed by the Oxygen Enhancement Ratio (OER) which depends, among others, on the oxygen level and the linear energy transfer (LET) of the radiation. Particle therapy benefits the treatment of hypoxic tumors compared to radiotherapy due to a decrease of OER when LET increases [Scifoni et al., 2013]. However, the irradiation of healthy tissues at the entrance channel remains a major limitation.
Nanotechnology brought new perspectives of using high-Z nanoparticles (NPs) to increase local radiation-effect. Previous studies performed by the group demonstrated that the radio-enhancement due to PtNPs is mostly related to the production of water radicals (OH) produced in the vicinity of the NPs [Porcel et al., 2010]. In parallel, it has been observed that the contribution of OH-mediated cell damage is strongly influenced by the presence of oxygen [Hirayama et al., 2013].
In the collaborative works performed at the Heavy Ion Medical Accelerator in Chiba (HIMAC, Japan) and at GSI-HIT (Germany), we investigated the effect of metallic NPs on human cancer cells incubated in oxic and hypoxic conditions and irradiated by carbon and helium ions. We have studied the variation of alpha and beta parameters in the presence of NPs. The presence of NPs might increase the direct lethal damage. This first study shows an attenuation of the amplification effect by NPs in the absence of oxygen. This gives new insights in the processes involved in the radio-enhancement by NPs.
This work is part of the European Commission Framework 7 Programme (grant number EC FP7 MC – ITN – 608163 – ARGENT) (www.itn-argent.eu).

Decoherence produced by spin bath

Erik Torrontegui (IFF, CSIC)
Date & location: Tue Apr 18 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Any quantum system is never isolated and represents an open system. As result, the environment that surrounds the system introduces decoherence spoiling its quantum properties. Employing an alternative formalism to study open quantum systems, the Stochastic Surrogate Hamiltonian, we analyze dissipation and dephasing processes produced by a spin bath. For dissipation, we show that the Stochastic Surrogate Hamiltonian enables the simulation of thermalization beyond the weak and Markovian regimes. For dephasing, the relation with temperature is studied, showing that the effect depends on the dephasing mechanism itself.

[1] E. Torrontegui and R. Kosloff, New J. Phys. 18, 093001 (2016).
[2] R. Baer and R. Kosloff, J. Chem. Phys. 106, 21 (1997).
[3] G. Katz, M. A. Ratner, and R. Kosloff, J. Phys. Chem. C 118, 21798 (2014).2017


Agregados de agua en nanoestructuras de carbono

José Bretón (Departamento de Física, Universidad de la Laguna)
Date & location:  Wed Mar 22 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: En   este Seminario presentamos   un   estudio  teórico sistemático   de   las configuraciones  de  mínima  energía  que  presentan  pequeños  agregados  de agua  (de  hasta  20  moléculas)  en  interacción  con  nano  estructuras  formadas básicamente por átomos de carbono. Las nanoestructuras de carbono que se analizan son:  hidrocarburos policíclicos  aromáticos,  como  el coroneno  y  el coranuleno, grafeno  y  grafito,  fulerenos  y  nanotubos  de  carbono.  Para  estos dos  últimos  también presentamos  los  efectos  asociados  al confinamiento  de estos  agregados  de  agua en  el  interior  de  las cavidades  huecas asociadas  a estas estructuras.Todos  estos  estudios  pretenden  contribuir a  la  comprensión de los fundamentos  nanoscópicos de la hidrofobicidad de la interacción agua-estructuras de carbono.

Classical and semiclassical energy conditions

Prado Martín Moruno (Departamento de Física Teórica I, Universidad Complutense de Madrid)
Date & location: Tue Mar 21 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: The standard energy conditions usually associated to general relativity are (mostly) linear in the stress-energy tensor, and have clear physical interpretations in terms of geodesic focussing, but suffer the significant drawback that they are often violated by semi-classical quantum effects. In contrast, it is possible to develop non-standard energy conditions that are intrinsically non-linear in the stress-energy tensor, and which exhibit much better well-controlled behaviour when semi-classical quantum effects are introduced, at the cost of a less direct applicability to geodesic focussing. In this talk I will review the standard energy conditions and their various limitations. Then, I will briefly introduce the averaged energy conditions, and present in detail the nonlinear and the semi-classical energy conditions.

Edge transport over sub-millimeter distance in the 2D Topological Insulator InAs/GaSb

Enrique Díaz (Departamento de Física Fundamental, Universidad de Salamanca)
Date & location: Fri Mar 14 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: The InAs/GaSb double quantum well (DQW), a tunable two dimensional (2D) electron-hole system, was recently proposed as a 2D topological insulator (TI) [1]. While convincing evidence for transport by edge states in micrometer-sized devices has been reported in several experiments [2, 3, 4], the topological origin of these transport  properties is still under debate [5]. In the present work we test the transport by edge states in several DQW’s with diferrent sizes InAs/GaSb to cover from normal insulator (NI) and TI samples up to unprecedented length scales and high magnetic fields. First of all, we address the low-temperature electrical transport in a local measurement configuration (Fig.1 (a)), both in zero-field and in the integer quantum Hall regime (Fig.1 (c)), with the latter indicating the realization of a non-trivial system [6]. Successively, making use of non-local transport measurements (Fig.1 (b), (d)), we consistently find evidence for transport by edge states over sub-millimeter distances, as tested using the methodology of Refs.[2, 3] and applying a resistor network model analogous to the one of Ref.[4]. Under high magnetic fields (up to B = 30 T), we detect persistent transport by edge states, with a clear suppression of backscattering in the case of perpendicular orientation. We analyse the response of the edge states to systematic inversions of the current contacts  and/or of the polarity of the magnetic field. Many-body interactions can produce exotic novel ground states in these systems. An interacting electron and hole can spontaneously form excitons, i.e. a neutral bound state provided that the exciton binding energy exceeds the energy separation between the single particle states.

[1] C.X. Liu, T.L Hughes, X.L. Qi, K. Wang and S.C Zhang, Phys. Rev. Lett. 100, 236601 (2008). [2] K. Suzuki, Y. Harada, K. Onomitsu, and K. Muraki, Phys. Rev. B  87, 235311 (2013). [3] K. Suzuki, Y. Harada, K. Onomitsu, and K. Muraki, Phys. Rev. B  91, 245309 (2015).
[4] S. Mueller et al:, Phys. Rev. B 92, 081303(R) (2015).
[5] F. Nichele et al:, arXiv:1511.01728.
[6] B. Büttner et al:, Nature Phys. 7, 418 (2011).

Not so normal modes

Gonzalo Muga (Dpto. de Química-Física, UPV/EHU)
Date & location: Mon Mar 06 2017 16:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: I will present the theory of time-dependent point transformations to find independent dynamical normal modes for two-dimensional systems subjected to time-dependent control in the limit of small oscillations. The condition that determines if the independent modes can indeed be defined is identified, and a geometrical analogy is put forward. The results explain and unify recent work to design fast operations on trapped ions, needed to implement a scalable quantum-information architecture: Transport,expansions, and the separation of two ions,two-ion phase gates, as well as the rotation of an anisotropic trap for an ion, are treated and shown to be analogous to a mechanical system of two masses connected by springs with time-dependent stiffness.
REF: PRA 95 022130 (2017)

Quantum walks gravity simulation

Giuseppe di Molfetta (Laboratoire d’Informatique Fondamentale, CNRS/Université Aix-Marseille )
Date & location: Fri Feb 24 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: As we know, spacetime is not flat at the cosmological scale. In order to describe spacetime, in General Relativity theory (GR), we need a continuous and differentiable manifold and a formal way to account for the continuous distortion of the metrics. The main point is that changing coordinate systems should not affect physics  laws (General Covariance). However at the Planck length, matter is not continuous and obeys Quantum Theory (QT). Although one century has passed, finding an intrinsically discrete counterpart of GR is still an open question. In fact, discretized GR does not turn out in just a mere finite difference scheme of the old formula.
I recently showed that one way to describe a discrete curved spacetime is by using Quantum Walks. From a physical perspective a QW describes situations where a quantum particle is taking steps on a discrete grid conditioned on its internal state (say, spin states). The particle dynamically explores a large Hilbert space associated with the positions of the lattice and allows thus to simulate a wide range of transport phenomena.
It is surprising that this unitary and local dynamics, defined on a rigid space-time lattice coincides in the continuous limit with the dynamical behavior of a quantum spinning-particle spreading on a curved spacetime. This could really turn out to be a powerful quantum numerical method to discretize GR.

Quantum optics in low dimensions: from fundamentals to applications

Alejandro González Tudela (Max-Planck-Institut für Quantenoptik)
Date & location: Fri Feb 10 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Recent experimental developments in nanophotonics [1], circuit QED [2] and cold atoms [3] allow to engineer systems where quantum emitters couple to low dimensional photon-like reservoirs with non-trivial energy dispersion. Compared to three-dimensional and structureless baths, the interactions induced by such structured environments can be strongly enhanced and have long-range character.

In this talk, I will show several phenomena that can emerge in these scenarios such as the existence of multi-photon bound states around single quantum emitters [4], the generation of tuneable long-range coherent interactions [5], or how one can boost the fidelities and efficiencies of non-classical states of light [6].

[1] Nature 508, 241–244 (2014), Nature Communications 5, 3808 (2014), Rev. Mod. Phys. 87, 347 (2015)
[2] Nature Physics 13 (1), 48-52 (2017)
[3] Nature Physics 8, 267–276 (2012),Physical Rev Lett. 101 (26), 260404 (2010)
[4] Physical Review X 6 (2), 021027 (2016)
[5] Nature Photonics 9 (5), 320-325 (2015), PNAS, 201603777 (2016)
[6] Physical Review Letters 115 (16), 163603 (2015), New Journal of Physics 18 (4), 043041 (2016) arXiv:1603.01243

Anomalies (in) matter

Karl Landsteiner (IFT, UAM-CSIC)
Date & location: Tue Jan 24 2017 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: The concept of symmetry is one cornerstone of modern theoretical physics, quantum mechanics is another. Sometimes they are incompatible with each other. These incompatibilities are called anomalies.
They constrain possible fermion spectra of gauge theories and explain otherwise forbidden processes such as the decay of the neutral pion into two photons. In the recent years however anomalies play an ever bigger role in a totally different realm of physics: condensed matter. In particular anomalies induce exotic new transport phenomena such as the chiral magnetic and the chiral vortical effects.
I will review of chiral anomalies, anomaly induced transport phenomena and discuss some of its applications in a new exciting class of materials: the Weyl semimetals.

Machine Intelligence and quantum information processing

Peter Wittek (ICFO)
Date & location: Fri Jan 13 2016 12:00:00 GMT+0200 (CEST), Seminar Room, Serrano 121 (CFMAC)

Abstract: Statistical learning theory is rich in results that changed the way we process and think about data. Furthermore, the theory offered a fresh perspective on artificial intelligence. Applications are countless and much progress has been made in applying learning schemes in quantum control problems. Quantum information processing and quantum computing are the next frontier for machine learning, but benefits work both ways: quantum-enhanced learning is also a promising research direction, but we must generalize known classical results to the quantum case to fully understand the limits and possibilities. This talk gives an introduction to the core concepts in learning theory, and then looks at the major challenges in the intersection of machine learning, artificial intelligence, and quantum information processing.