- Badih Assaf (2014- Aug 2018) / Current position : Assistant (...)
- Tatsuo Azeyanagi (2013-2016) / Current position : Post Doctoral (...)
- Jacopo De Nardis (2016- Sept 2018) / Current position : FWO (...)
- Maurizio Fagotti (2015-2017) / Current position : ‘Chargé de (...)
- Anastasia Fialkov (2013-2015) / Current position : ITC Fellow, (...)
- Emmanuel Flurin (2017-June 2018) / Current position : Permanent (...)
- Michael Köpf (2013-2015) / Current position : Work in (...)
- Leonardo Mazza (2015-August 2018) / Current position : Maître de (...)
- Joshua McGraw (2015-2017) / Current position : ‘Chargé de (...)
- Olga Petrova (2016- Aug 2018) / Current position : Work in (...)

Badih’s research interests are primarily focused on studying and understanding the electronic properties of 2D materials and topological insulators. The most common 2D material is graphene which is essentially a single atomic sheet of carbon. Topological insulators, on the other hand, are 3D materials that are semiconducting in the bulk but highly conducting on the surface. Such materials are extremely attractive as potential silicon alternatives in data processing devices as well as for applications in memory devices and optoelectronics.

After completed his Bachelors degree in physics at the American University of Beirut in 2009, he spent five years as a graduate student at Northeastern University. As a member of the Heiman group at Northeastern, and a visiting scientist at MIT with the Moodera group, he spent the bulk of my PhD work studying quantum coherent transport in topological insulator thin films grown by molecular beam epitaxy. He also took part in a project that involved studying the properties of novel spin-gapless Heusler alloys.

As a JRC at the Ecole Normale Supérieure, he was directly involved with groups from the Laboratoire Pierre Aigrain that are working on probing the fundamental electronic properties of 2D materials as well as different topological material systems (Bi2Se3, Bi2Te3…) using gigahertz transport probes and terahertz spectroscopy.

**Selected Publications**

G. Krizman, B.A. Assaf, M. Orlita, T. Phuphachong, G. Bauer, G. Springholz, G. Bastard, R. Ferreira, L.A. de Vaulchier, Y. Guldner.

“Avoided level crossing at the magnetic field induced topological phase transition

due to orbital mixing” submitted arxiv1808.03361

G. Krizman, B.A. Assaf, T. Phuphachong, G. Bauer, G. Springholz, G. Bastard, R. Ferreira, L.A. de Vaulchier, Y. Guldner. “Tunable Dirac interface states in topological superlattices” Phys. Rev. B 98 075303 (2018). Arxiv1806.04676.

D. Walkup, B.A. Assaf, K.L. Scipioni, R. Sankar, F. Chou, G. Chang, H. Lin, I. Zeljkovic, V. Madhavan, “Interplay of orbital effects and nanoscale strain in topological crystalline insulator.” Nature Communications 9 1550 (2018). arxiv1610.09337.

Inhofer, J. Duffy, M. Boukhicha, E. Bocquillon, J. Palomo, K. Watanabe, T. Taniguchi, I. Estève, J.M. Berroir, G. Fève, B. Plaçais, B.A. Assaf. “RF compress

ibility of topological insulator Bi2Se3- in the bulk depleted regime”, Physical Review Applied 9 024022 (2018). arxiv1707.01657

B.A. Assaf, T. Phuphachong, E. Kampert, V. Volobuev, P. Mandal, J. Sanchez-Barriga, O. Rader, G. Bauer, G. Springholz, L.A. de Vaulchier, Y. Guldner, “Negative magnetoresistance from anomalous N=0 Landau level in topological matter”. Physical Review Letters 119, 106602 (2017) arxiv 1704.02021. **Highlighted as Editors’ Suggestion.**

Inhofer, S. Tchoumakov, B.A. Assaf, G. Fève, J.M. Berroir, V. Jouffrey, D. Carpentier, M. Goerbig, B. Plaçais, K. Bendias, D.M. Mahler, E. Bocquillon, E. Schlereth, C. Brüne, H. Buhmann, L.W. Molenkamp. “Topological confined massive surface states in strained bulk HgTe probed by RF compressibility”, Physical Review B 96 195104 (2017) arxiv.1704.04045. Highlighted as Editors’ Suggestion.

T. Phuphachong, B.A. Assaf, V.V. Volobuev, G. Springholz, G. Bauer, L.A. de Vaulchier, Y. Guldner. “Magnetooptical evidence of the topological phase transition in (111)-Pb1-xSnxTe. Journal of Physics : Conference Series. 864, 012038 (2017).

B.A. Assaf, T. Phuphachong, V.V. Volobuev, G. Springholz, G. Bauer, L.A. de Vaulchier, Y. Guldner. “Magnetooptical determination of a topological index”. Nature partner journals Quantum Materials. 2, 26 (2017) arxiv : 1608.08912

T. Phuphachong, B.A. Assaf, V.V. Volobuev, G. Springholz, G. Bauer, L.A. de Vaulchier, Y. Guldner. “Dirac Landau Level Spectroscopy in Pb1−xSnxSe and Pb1−xSnxTe across the Topological Phase Transition : A Review”. Crystals 7, 29 (2017)

V. Callewaert, K. Shastry, R. Saniz, I. Makkonen, B. Barbiellini, B. A. Assaf, D. Heiman, J.S. Moodera, B. Partoens, A. Bansil, A. Weiss, “Positron surface state as a new spectroscopic probe for characterizing surfaces of topological insulator materials”. Physical Review B. 94, 115411 (2016)

F. Katmis, V. Lauter, F.S. Nogueira, B.A. Assaf, M.E Jamer, P. Wei, B. Satpati, J.W. Freeland, I. Eremin, D. Heiman, P. Jarillo-Herrero, J.S. Moodera, “A high-temperature ferromagnetic topological insulating phase by proximity coupling.” Nature 533, 513, (2016)

Tatsuo received his Ph.D. in Science from Kyoto University in March, 2011. He then continued his research at RIKEN and is a Fellow of Harvard University now. He has worked on string theory and quantum field theories.

His current main research interests are :

microscopic analysis of black holes based on string theory and gauge/gravity dualities

large-N gauge theories, matrix models and their relations to string/M theory.

**Selected publications**

"The Spectrum of Strings on Warped AdS3xS3," Tatsuo Azeyanagi, Diego M. Hofman, Wei Song and Andrew Strominger, arXiv:1207.5050[hep-th]

"Large-N reduction in QCD-like theories with massive adjoint fermions," Tatsuo Azeyanagi, Masanori Hanada, Mithat Unsal and Ran Yacoby, Phys.Rev.D82(2010)125013

"Higher-Derivative Corrections to the Asymptotic Virasoro Symmetry of 4d Extremal Black Holes," Tatsuo Azeyanagi, Geoffrey Compere, Noriaki Ogawa, Yuji Tachikawa and Seiji Terashima, Prog.Theor.Phys.122(2009)355-384

"Phase structure of twisted Eguchi-Kawai model," Tatsuo Azeyanagi, Masanori Hanada, Tomoyoshi Hirata and Tomomi Ishikawa, JHEP 0801(2008)025

"Near Extremal Black Hole Entropy as Entanglement Entropy via AdS2/CFT1," Tatsuo Azeyanagi, Tatsuma Nishioka and Tadashi Takayanagi, Phys.Rev.D77(2008)064005

Jacopo received his master in theoretical physics at the University of Pisa in 2011 under the supervision of Prof. Pasquale Calabrese and then he moved to the University of Amsterdam (UvA) for a PhD under the supervision of Prof. Jean-Sébastien Caux. Here he explored widely the realm of one-dimensional interacting integrable models. Despite the fact that the eigenstates and the spectra of these models are known, the study of their equilibrium and non-equilibrium correlation functions is a challenging task. However they constitute the simplest realizations of truly interacting quantum models, providing therefore an optimal outpost where to understand the role of strong interactions in equilibrium and non-equilibrium quantum physics.

Current research interests are out-of-equilibrium dynamics and equilibrium dynamical correlations of integrable systems in the thermodynamic limit, together with the study of non-equilibrium strongly interacting classical statistical models which are mappable to quantum integrable models (Kardar-Parisi-Zhang equation, Simple Exclusion Processes)

**Selected Publications**

M. Panfil, J. De Nardis, J-S Caux, Metastable criticality and the super Tonks-Girardeau gas, Phys. Rev. Lett. 110, 125302 (2013)

J. De Nardis, B. Wouters, M. Brockmann, J-S Caux, Solution for an interaction quench in the Lieb-Liniger Bose gas, Phys. Rev. A 89, 033601 (2014)

B. Wouters, J. De Nardis, M. Brockmann, D. Fioretto, M. Rigol, J-S Caux, Quenching the Anisotropic Heisenberg Chain : Exact Solution and Generalized Gibbs Ensemble Predictions, Phys. Rev. Lett. 113, 117202 (2014)

J. De Nardis and J-S Caux, Analytical expression for a post-quench time evolution of the one-body density matrix of one-dimensional hard-core bosons, J. Stat. Mech. (2014) P12012

J. De Nardis and M. Panfil, Density form factors of the 1D Bose gas for finite entropy states, arXiv:1411.4537 (2014)

Maurizio did his PhD at the University of Pisa (Italy) under the supervision of Prof. Pasquale Calabrese. The focus was on two subjects of research in low-dimensional quantum many-body systems : the scaling behaviour of the entanglement entropies (von Neumann and Rényi entropies) and the non-equilibrium time evolution of a state after a sudden quench of a global Hamiltonian parameter (global quantum quench). In autumn 2011 he moved to Oxford (UK) as a postdoctoral research assistant to collaborate with Prof. Fabian Essler on the latter topic. Current research interests are well characterised by the following keywords : quantum quenches, integrable models, relaxation/thermalisation, entanglement.

**Selected Publications**

M. Fagotti, *“On Conservation Laws, Relaxation and Pre-relaxation after a Quantum Quench”*, arXiv:1401.1064 (2014)

M. Fagotti and F.H.L. Essler, *“Stationary behaviour of observables after a quantum quench in the spin-1/2 Heisenberg XXZ chain”*, J. Stat. Mech. (2013) P07012

M. Fagotti and F.H.L. Essler, *“Reduced Density Matrix after a Quantum Quench”*, Phys. Rev. B 87, 245107 (2013)

F.H.L. Essler, S. Evangelisti, and M. Fagotti, *“Dynamical Correlations after a Quantum Quench”*, Phys. Rev. Lett. 109, 247206 (2012)

P. Calabrese, F.H.L. Essler, and M. Fagotti, *“Quantum Quench in the Transverse Field Ising Chain”*, Phys. Rev. Lett. 106, 227203 (2011)

Anastasia’s research interests are very broad and include different topics in theoretical cosmology and astrophysics, such as 21-cm cosmology, large-scale structure, the Cosmic Microwave Background radiation, gravitational lensing, inflation and other related fields.

She explored the properties of the redshifted 21-cm signal of neutral hydrogen from the epoch of primordial star formation (10 < z < 60) and analyze prospects for future detection of the 21-cm signal by instruments such as Square Kilometer Array.

She is also interested in modeling and constraining astrophysical processes at high redshifts, as well as developing methods to learn about the nature of dark matter and dark energy using future 21-cm measurements.

She did her PhD at Tel Aviv University working with Prof. N. Itzhaki and Prof. R. Barkana on two subjects : cosmological signature of pre-inflationary relics, and first stars and their imprints in the 21-cm signal.

**Selected publications**

"The 21-cm signature of the first stars during the Lyman-Werner feedback era", Fialkov A., Barkana R., Visbal E., Tseliakhovich D., Hirata C. M., MNRAS, submitted

"The signature of the first stars in atomic hydrogen at redshift 20’’, Visbal E., Barkana R., Fialkov A., Tseliakhovich D., Hirata C. M., 2012 Nature

"Impact of the relative motion between dark matter and baryons on the first stars : semi-analytical modelling" Fialkov A., Barkana R., Tseliakhovich D., Hirata C. M., 2012, MNRAS, 242

"How Sensitive is the CMB to a Single Lens ?" Rathaus B., Fialkov A., Itzhaki N., 2011 JCAP, 033

"Cosmological Imprints of Pre-Inflationary Particles" Fialkov A., Itzhaki N., Kovetz E. D., 2010, JCAP, 004

Emmanuel Flurin did his PhD thesis at the physics department, ENS, in the group of B. Huard and got very interesting results on microwave amplification at the quantum limit. He received a solid training at the Laboratoire Pierre Aigrain in which design of challenging experiments was always paired up with explorations of deep theoretical concepts. He also used superconducting circuits to manipulate the quantum state of light trapped in high finesse microwave cavities.

He went on as a postdoc at Berkeley, in California, on a similar topic as his thesis, in the prestigious group of Prof. Irfan Siddiqi.

As a JRC at ENS his project consisted in exploiting original quantum resources at microwave frequencies to enhance the position metrology of a mechanical oscillator. Beyond its own scientific interest, this project also brings many synergies in term of experimental skills, research interests and cutting edge equipment with the LKB group (ENS).

Selected publicationsRetour ligne manuel

Observing topological invariant using quantum walk in superconducting circuits. E Flurin, VV Ramasesh, S Hacohen-Gourgy, N Yao, I Siddiqi ; arXiv preprint 1610.03069 (submitted)Retour ligne manuel

Direct Probe of Topological Invariants Using Bloch Oscillating Quantum Walks. VV Ramasesh, E Flurin, M. Rudner, I Siddiqi, N Yao ; arXiv preprint 1609.09504 (submitted)Retour ligne manuel

Simultaneous measurement of non-commuting observables in circuit QED. S Hacohen-Gourgy, L Martin, E Flurin, VV Ramasesh, B Whaley, I Siddiqi ; Nature 538, 491 (2016)Retour ligne manuel

Stabilizing entanglement via symmetry-selective bath engineering in superconducting qubits. ME Schwartz, L Martin, E Flurin, C Aron, M Kulkarni, HE Tureci, I Siddiqi ; Physical Review Letters, 116 (24), 240503 (2016)Retour ligne manuel

A compact design for the Josephson mixer : The lumped element circuit. JD Pillet, E Flurin, F Mallet, B Huard ; Applied Physics Letters 106 (22), 222603 (2015)Retour ligne manuel

Quantum dynamics of an electromagnetic mode that cannot have N photons. L Bretheau, P Campagne-Ibarcq, E Flurin, F Mallet, B Huard ; Science 348 (6236), 776-779 (2015)Retour ligne manuel

Superconducting quantum node for entanglement and storage of microwave radiation. E Flurin, N Roch, JD Pillet, F Mallet, B Huard ; Physical review letters 114 (9), 090503 (2014)Retour ligne manuel

The Josephson mixer, a Swiss army knife for microwave quantum optics. E Flurin ; Thesis manuscript (2014)Retour ligne manuel

Observing interferences between past and future quantum states in resonance fluorescence. P Campagne-Ibarcq, L Bretheau, E Flurin, A Auffèves, F Mallet, B Huard ; Physical review letters 112 (18), 180402 (2014)Retour ligne manuel

Persistent Control of a Superconducting Qubit by Stroboscopic Measurement Feedback. P Campagne-Ibarcq, E Flurin, N Roch, P Morfin, M Mirrahimi, MH Devoret, F Mallet, B Huard Physical Review X 3 (2), 021008 (2013)Retour ligne manuel

Generating Entangled Microwave Radiation Over Two Transmission Lines. E Flurin, N Roch, F Mallet, MH Devoret, B Huard ; Physical review letters 109 (18), 183901 (2012) ; APS Physics Viewpoint : Entangled Microwaves Split Up by Göran JohanssonRetour ligne manuel

Widely Tunable, Nondegenerate Three-Wave Mixing Microwave Device Operating near the Quantum Limit. N Roch, E Flurin, F Nguyen, P Morfin, P Campagne-Ibarcq, MH Devoret, B Huard ; Physical review letters 108 (14), 147701 (2012)Retour ligne manuel

Interconnect-free parallel logic circuits in a single mechanical resonator. I Mahboob, E Flurin, K Nishiguchi, A Fujiwara, H Yamaguchi ; Nature communications 2, 198 (2011)Retour ligne manuel

Enhanced force sensitivity and noise squeezing in an electromechanical resonator coupled to a nanotransistor. I Mahboob, E Flurin, K Nishiguchi, A Fujiwara, H Yamaguchi ; Applied Physics Letters 97 (25), 253105 (2010)Retour ligne manuel

As a mathematically inclined student of physics at the University of Münster, Germany, Michael was attracted to the science of nonlinear dynamics and self-organization. During his PhD studies, he applied his expertise in this area to develop a theoretical model of the spontaneous formation of nanoscopic stripe patterns in coating processes using mono-molecular layers - a research project that allowed to bridge between fundamental science and technological application.

After obtaining his PhD, Michael’s main interest shifted towards the ultimate form of self-organization : Life. Receiving a postdoctoral scholarship from the Human Frontier Science Program, he moved to the Technion in Haifa, Israel, to work on the mathematical description of biological and bio-mimetic materials in various contexts, ranging from the dynamics of tissue during wound healing to artificial muscles made of nematic elastomers, fascinating materials that combine the properties of liquid crystals and rubbers.

In his project "Growth and Development in Biological Systems : From Bacteria to Olive Trees" he will now work together with his colleagues at the ENS on growth and development on the various different scales of life, from growing bacteria colonies to growth processes in larger plants and animals. Perpetual change by growth and self-organized restructuring is a defining property of life. Its understanding remains a major challenge to modern science as it is a prerequisite of new biotechnology and the medicine of our future. Michael hopes that his research will help to pave the way in this direction.

More information regarding Michael’s research can be found on his website www.michaelkoepf.de

After undergraduate studies at the University of Pisa and at Scuola Normale, in 2008 Leonardo moved to Munich to pursue my PhD in the group of Ignacio Cirac at the Max-Planck-Institut of Quantum Optics, obtained in 2012. During his graduate studies he was introduced to the subjects of ultra-cold atoms and quantum simulations, with a strong focus on topological phases of matter. Afterwards, he moved back to Pisa for a post-doc in the group of Rosario Fazio, where he sharpened skills in the numerical simulations of one-dimensional systems and got interested in out-of-equilibrium quantum physics.

He currently worked on the effect of interactions in cold atomic gases coupled to synthetic gauge potentials and on the possible identification of topological phases of matter in such setups. Parallely, he joined the study of Majorana fermions in low-dimensional superconductors, focussing both on the development of the corresponding number-conserving theory and on the understanding of the quantum-information potential of such quasi-particles. Finally, employing numerical techniques especially suited for one-dimensional systems, he is studying several aspects of their non-equilibrium physics, from energy transport to dissipation.

**Selected publications**

Localized Majorana-like modes in a number conserving setting : An exactly solvable model. Iemini, Mazza, Rossini, Diehl and Fazio, arXiv:1504.04230 (2015).

Magnetic crystals and helical liquids in alkaline-earth fermionic gases.

Barbarino, Taddia, Rossini, Mazza and Fazio, arXiv:1504.00164 (2015).

Robustness of quantum memories based on Majorana zero modes.

Mazza, Rizzi, Lukin and Cirac, PRB 88, 205142 (2013).

Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators.

Endres, Cheneau, Fukuhara, Weitenberg, Schauß, Gross, Mazza, Bañuls, Pollet, Bloch and Kuhr, Science 334, 200 (2011).

Wilson Fermions and Axion Electrodynamics in Optical Lattices.

Bermudez, Mazza, Rizzi, Goldman, Lewenstein and Martin-Delgado, PRL 105, 190404 (2010).

Josh is an experimental soft condensed matter physicist. He studied physics at Dalhousie University (Canada) as an undergraduate, before moving to McMaster University (Canada) to work in the Dalnoki-Veress group, obtaining a PhD in confined polymer physics, organic glasses, and thin film flows in 2012. Then, he worked until 2015 in the Jacobs group at Saarland University (Germany) as an NSERC postdoctoral fellow. There, his investigations focussed mainly on the slip hydrodynamic boundary condition. In all of these studies, central guides were the fascinating properties of surfaces and interfaces, and their effects in flows of sub-micrometric systems. As a JRC in LPS, using his PSL and international collaborative network, Josh intends to accentuate research in these topics at the nanoscale, along with a move towards elastohydrodynamics — a rising field crucial to soft and bio systems.

**Selected publications** :

S. Haefner, M. Benzaquen, O. Bäumchen, T. Salez, R. Peters, J.D. McGraw, K. Jacobs, E. Raphaël, K. Dalnoki-Veress, Influence of Slip on the Plateau-Rayleigh Instability on a Fibre, Nature Communications (in press) ; arXiv:1501.02194.

J.D. McGraw, O. Bäumchen, M. Klos, S. Haefner, M. Lessel, S. Backes and K. Jacobs, Nanofluidics of thin polymer films : Linking the slip boundary condition at solid-liquid interfaces to macroscopic pattern formation and microscopic interfacial properties, Advances in Colloid and Interface Science, 210 (2014) 13.

Y. Chai, T. Salez, J.D. McGraw, M. Benzaquen, K. Dalnoki-Veress, E. Raphaël, J. Forrest, A Direct Quantitative Measure of Surface Mobility in a Glassy Polymer, Science, 343 (2014) 994.

J.D. McGraw, T. Salez, O. Bäumchen, E. Raphaël, K. Dalnoki-Veress, Self-Similarity and Energy Dissipation in Stepped Polymer Films, Physical Review Letters, 109 (2012) 128303.

S. Cormier, J.D. McGraw, T. Salez, E. Raphaël, K. Dalnoki-Veress, Beyond Tanner’s Law : Crossover Between Spreading Regimes of a Viscous Droplet on an Identical Film, Physical Review Letters, 109 (2012) 154501.

Olga is a theoretical condensed matter physicist, currently focusing on various aspects of quantum magnetism. She received her Ph. D. from Johns Hopkins University (USA) in the summer of 2013. She completed her Ph. D. thesis, titled "Topological defects and textures in complex magnets", under the guidance of Prof. Oleg Tchernyshyov. Olga then moved on to her first postdoctoral appointment at the Max Planck Institute for the Physics of Complex Systems (Germany), where she was supported by the Research Fellowship for Postdoctoral Researchers from the Alexander von Humboldt Foundation. Since September 2016, Olga has held the junior research chair at the Ecole Normale Supérieure. Here she has been collaborating on the studies of quantum spin liquids with Nicolas Regnault from Laboratoire Pierre Aigrain, and additionally has been conducting travaux diriges for the M1 Statistical Physics course taught at the ENS.

**Selected pulications**

"Coulomb potential V (r)= 1/r problem on the Bethe lattice", O Petrova, R Moessner, Physical Review E 93 (1), 012115 (2016)

"Hydrogenic states of monopoles in diluted quantum spin ice", O Petrova, R Moessner, SL Sondhi, Physical Review B 92 (10), 100401 (2015)

"Projective symmetry of partons in the Kitaev honeycomb model", P Mellado, O Petrova, O Tchernyshyov, Physical Review B 91 (4), 041103 (2015)

"Unpaired Majorana modes on dislocations and string defects in Kitaev’s honeycomb model", O Petrova, P Mellado, O Tchernyshyov, Physical Review B 90 (13), 134404 (2014)