80th anniversary of physics - msu.rupulses using the spectral filter. such attosecond shock waves...

In 1933 Physics-Mathematics Facultyof Lomonosov Moscow State Universitywas spilt into the Faculty of Mechanicsand Mathematics and the Faculty ofPhysics, so that in November 2013 theFaculty of Physics celebrated its 80thanniversary. The respective commemora-tive meeting was organized at theIntellectual Center-Fundamental Libraryof Moscow State, and Prof. Nikolay N.Sysoev, dean of the Faculty, delivered areport on the history, nowadays, and thefuture of our Faculty of Physics.

Rector of Lomonosov Moscow StateUniversity, Prof. Victor A. Sadovnichii,as well as many other MSU deans, rectorsand the directors of the Universities andinstitutes from allover Russia congratu-lated the Faculty of Physics and its staffmembers and students with this wonder-ful date.

The Academic Chorus of LomonosovMoscow State University, amateurstudent groups, and wellknown in Russiabard and musician Sergey Nikitin, ourformer graduate, were also a part of theprogram of the commemorative meeting.

Within the frame of 80th anniversary,the Alumni Association of the graduatesfrom the Faculty of Physics organized aconference on "Fundamental science as aprecursor of the novel social-valuabletechnologies and business-organizationof modern high-tech businesses", whichwas a forum for the leading Russianscientists. Plus to that, a Concert ofPhysical Arts was organized at the MSUPalace of Culture that hosted both thelegendary opera "Archimedes" and thebest performances from the last "2013Physicists Day".

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of the Faculty of Physics, Lomonosov Moscow State University

In This Issue:

Scientific News

/2013SCIENCE 2NEWSLETTER №

80th Anniversaryof the Facultyof Physics

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Recearch highlights from the Faculty of PhysicsLomonosov Moscow State University/2013Science 2N №ewsletter

Discovery of opticaltransients with the helpof the telescope-robotsMASTER network

Physicists from Lomonosov Moscow State University discovered with the help of the network of the telescope-robotsMASTER two potentially dangerous asteroids and over 180 optical transients supernova stars, nova and recurrentnova stars, flares of the active nuclei of the galaxies, detection of the glares of unknown origin, etc.

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The network of the telescope-robots MASTER has been con-structed by a group of scientists fromthe Division of Astronomy, Faculty ofPhysics, and Steinberg AstronomicalInstitute, Lomonosov Moscow StateUniversity, headed by Prof. V.M. Li-punov with an aim to register andstudy the own optical radiation fromthe gamma-ray bursts, which is the

immediate task of the modernastronomy.

In 2013, the major results obtainedwith the help of the MASTERnetwork are the discovery of the twopotentially dangerous asteroids 2013SW2 и 2013 UG1 and of over 180optical transients — first kindsupernova star, nova and recurrentnova stars, flares of the active nuclei

of the galaxies, detection of the glaresof unknown origin, and discoveringof small bodies of the Solar system(dangerous asteroids and cometsinclusive). Plus to that, photometricand polarization measurements of theown optical radiation in 25 areas ofthe gamma bursts were made in mostcases for the first time.

Researchers from the Faculty of Physics, Lomonosov Moscow State University have discovered a new mechanism ofquasi-resonant excitation of coherent terahertz phonons in a bulk of dielectric with extremely large energy input up to100 kJ/cm . The results of this work were published in 10, p.076003, (2013).3

Laser Physics Letters

Efficient laser-plasmaexcitation of phononswith terahertz frequenciesin the bulkof a transparent dielectric

Range of phenomena occurring inthe interaction of tightly focusedfemtosecond laser radiation withdielectrics is quite broad: frommultiphoton and tunneling ionization,plasma electrons heating in the laserwave, impact ionization and excita-tion of coherent phonons and shock-wave propagation and as a result theformation of residual micromodifi-cations. Study of the excitation andrelaxation of coherent phonons shouldbe given special attention. They notonly give an idea of the vibrationalproperties of substances, but also canbe used to control the molecular andcollective motions, get special non-equilibrium states and facilitate che-mical or structural changes that cannotbe realized under normal conditions.

In their paper, the researchers of thePhysics Faculty of Moscow StateUniversity, working at the Department of General Physics and WaveProcesses, focused mainly on thestudy of these energy transfer processes: from laser to plasma (due toionization and heating of the plasmaelectrons on the time duration of thelaser pulse), from laser to phonons (attimes of the laser pulse duration) andfrom plasma to phonons (at thethermalization time of the electronplasma). The main feature of the workis to study the excitation of coherentphonons in the bulk crystals underextreme conditions determined by thelaser intensity up to 10 W/cm ,exceeding the ionization threshold ofthe medium. In this case, to the pro-

cess of excitation of coherent phononsby impulsive stimulated Ramanscattering one can add the effectivelaser energy transfer processes in thecrystal lattice through the plasmaelectrons. Laser-induced plasma pro-motes effective local heating medium,which may lead to a strong change inthe frequency of soft Raman activemodes in crystals near phase transi-tions and phonons anharmonicity.

What is the mechanism of excita-tion and relaxation of coherentphonons in the extreme conditions oflaser-induced plasma creation? It wasfound that the modern theory of thegeneration of coherent phonons(transient stimulated Raman scatter-ing and displacive mechanism) cannoteven outline the key results of the

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Recearch highlights from the Faculty of PhysicsLomonosov Moscow State University /2013SCIENCE 2NEWSLETTER №

One of the most exciting applica-tions of the modern nonlinear opticsemploy the light pulses of ultimatelysmall durations. The development of

femtosecond ( fs = s) lasersbrought an opportunity to visualizeand control chemical reactions.Attosecond technologies (1 as

10 s) will give tools to visualize andcontrol motion of electrons in theatoms and develop, for instance,atomic transistor — elementary unitof the ultrafast quantum electronics ofthe future.

Existing technologies of attose-cond pulse generation are rathercomplicated and yield low conver-sion efficiency and low attosecondpulse energy. In the joint work ofphyisicists from Moscow StateUniversity and Texas A&M University the generation of powerful,multigigawatt attosecond pulsesduring formation of three-dimen-sional optical shock waves wassimulated.

Formation of the shock waves, orabrupt changes of physical parame-ters, exhibiting wave-like propaga-tion properties, is a general propertyof nonlinear wave dynamics andtakes place in many branches of

physics: astrophysics, nonlinearacoustics, seismology, fluid dyna-mics and detonation physics. Largeclass of the shock waves appearswhen the wave propagation velocitydepends on the wave amplitude,which causes the leading edge of thepulse to steepen (if the pulse peaktravels faster than the pulse wings) orthe trailing edge to steepen (if thepulse peak travels slower than thepulse wings). In nonlinear optics theone-dimensional shock waves areknown to exist in the optical fibers. Itis also known that one-dimensionalshock waves distort the shape of thelight pulse, but do not change itsduration.

Numerical simulations, perfor-med using the "Lomonosov" and"Chebyshev" supercomputer clustersof the Moscow State University,demonstrate that in the three-dimensional case of free-spacepropagation the nonlinear spatio-temporal dynamics of the powerfulfemtosecond (with the initial duration20–50 fs) laser pulse leads to theformation of the shock wave ofattosecond duration (approx. 300 as).Specifically, the propagation me-dium is chosen to be helium, because

helium has the largest transparency

band (around 5 10 Hz = 21 eV)among the noble gases, and minimumduration of the shock wave isdetermined by absorption and dis-persion at the edges of the transpar-ency window. Laser pulse withcentral wavelength 800 nm, duration30 fs FWHM, power 1.4 TW (or0.8 Pcr, where Pcr is the cirtical self-focusing power) is loosely focused inthe low-pressure helium (heliumpressure is 0.02 bar). The formationof the attosecond wave is predictedpast the linear focal point, after ~ 20 mof propagation in helium.

At the attosecond shock waveformation point the energy flux is

relatively low (< 2 J/cm ), whichallows one to separate the attosecondpulses using the spectral filter. Suchattosecond shock waves will fosterthe investigation of the laws ofnonlinear optics at attosecond timescales and also comprise a promisingtool for visualization and control ofthe electron wavefunctions in atoms.The details of the work are publishedin , vol. 110,page 183903 in 2013.

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Physical Review Letters

Existence of optical shock waves of attosecond duration in the propagation of powerful near-infrared laser pulsesin low-pressure helium is predicted by the collaboration of physicists from Moscow State University and TexasA&M University.

Attosecond shock waves

experiments: a strong change of thephonon frequency, the time delay ofthe maximum amplitude of thephonon modes. It turns out that thefirst due to stimulated Raman scat-tering "seed" coherent phonons withterahertz frequencies are generated,and the plasma absorbs a significantpart of the laser pulse energy. Plasmaenergy is then quasi-resonantly trans-ferred from plasma electrons to

appeared "seed" coherent phonons.Quasi resonant nature of energyconversion is possible due to the largeamplitude of coherent phononsoscillations, which leads to a synchro-nous modulation of the dielectricbandgap. Such effective energytransferring from plasma electrons tocoherent phonons occurs in phasewith the vibrations of coherentphonons when the bandgap becomes

minimal. Proposed mechanism forthe generation of coherent phononsgives the complete explanation of theobserved phenomena.

To perform the work a unique setof engineering equipment purchasedunder the M.V. Lomonosov MoscowState University Development

was used.

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Dr. P. Zhokhov Prof. A. Zheltikov

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The existence of gravitationalwaves was predicted by Einsteinalmost a century ago. Now, a globalnetwork of gravitational wave obser-vatories is seeking to detect gravita-tional radiation generated by astro-physical sources. In essence, thesedevices are huge (kilometer-scale)Michelson interferometers, which canmeasure tiny (attometer-scale) varia-tions of their arm lengths (see Fig.1).Two largest and most sensitive ofthem, LIGO Hanford Observatory(LHO) and LIGO Livingston Obse-rvatory (LLO), are operated by theLIGO Scientific Collaboration (LSC)

a group of scientists from manyinstitutions worldwide, including theFaculty of Physics, LomonosovMoscow State University. In the end of2011, a squeezed light with reducedquantum fluctuations was injected intothe LHO interferometer, resulting inthe best broadband sensitivity togravitational waves ever achievedhttp://www.nature.com/nphoton/journal/v7/n8/full/nphoton.2013.177.html

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Seeing the big picture of functionalresponses within large neuralnetworks in a freely functioning brainis crucial for understanding thecellular mechanisms behind thehigher nervous activity, including themost complex brain functions, such ascognition and memory. As a break-through toward meeting this chal-lenge, implantable fiber-opticinterfaces integrating advancedoptogenetic technologies and cutting-

edge fiber-optic solutions have beendemonstrated, enabling a long-termoptogenetic manipulation of neuralcircuits in freely moving mice. Here,we show that a specifically designedimplantable fiber-optic interfaceprovides a powerful tool for parallellong-term optical interrogation ofdistinctly separate, functionallydifferent sites in the brain of freelymoving mice. This interface allowsthe same groups of neurons lying

deeply in the brain of a freely behav-ing mouse to be reproducibly accessedand optically interrogated over manyweeks, providing a long-termdynamic detection of genome activityin response to a broad variety ofpharmacological and physiologicalstimuli.

The results of this work have beenpublished in (1), , 3,(2013).; (2), ,102, 161113 (2013).

Scientific reportsApplied Physics Letters

Parallel multisite long-term optical dynamic braininterrogationin freely moving mice

Squeezed light enhancessensitivityof the LIGO gravitationalwaves detector

Physicists from Moscow State Univ. within International collaboration show that the LIGO detector demon-strates with the injection of squeezed states the best broadband sensitivity to gravitational waves ever achieved.

LIGO

Fig. 1

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An electromagnetic field can bedescribed by two non-commutingconjugate operators, known as"phase" and "amplitude" quadratures. A coherent state of light hasequal uncertainties in both quadratures, with the uncertainty productlimited by the Heisenberg uncertaintyprinciple. For a squeezed state, theuncertainty in one quadrature isdecreased relative to that of thecoherent state. Note that the uncer-tainty in the orthogonal quadrature iscorrespondingly increased, alwayssatisfying the Heisenberg inequality(see the green box in Fig. 1).

The grey box in Fig. 1 shows asimplified schematic of the squeezedstate source used in the LHO squeez-ing experiment. The "pump laser" forthe squeezed vacuum source is phase-locked to the main laser of theinterferometer ("H1 laser"), and itemits 1.064 nm light, which drives thesecond harmonic generator (SHG) toproduce light at 532 nm. This light, inturn, pumps the optical parametricoscillator (OPO) and producessqueezed vacuum at 1.064 nm viadegenerated parametric down-conver-sion process.

During the reported experiment,the quantum noise was the limiting

noise source above 400 Hz andcontributed significantly to the totalnoise down to 150 Hz. The signifi-cantly improved sensitivity due tosqueezing in this experiment is shownin Fig.2.

The performance without squee-zing shown by the red curve. The bluecurve shows the improvement in thesensitivity resulting from squeezing,with a 2.15 dB reduction in the noise.This constitutes the best broadbandsensitivity to gravitational waves everachieved.

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Antisunward structureof thin current sheets in theEarth's magnetotail waspredicted

Physicists from Moscow State Univ. in collaboration with researchers from IKI RAS first constructed a two-dimensionalquasi-adiabatic model of a thin current sheet in the magnetotail based on its longitudinal inhomogeneity. Theypredicted an antisunward structure of thin current sheets in the Earth’s magnetotail.

A self-consistent kinetic model ofthin current sheets (TCS) wasdeveloped, taking into account theinhomogeneity of TCS parameters inthe antisunward direction. It wasshown that the charged particledynamics depending on the magneticfield distribution in the downtaildirection completely determines themagnetotail equilibrium structure. Wedemonstrate that transient ions as wellas electrons are the main currentcarriers in this system, but the firstones support mostly the background(1D) structure of the current sheet. Theinfluence of electrons and quasi-

trapped ions is found to vary depend-ing upon downtail distance along thesheet. Assuming the conservation ofthe so-called quasi-adiabatic invari-ant, we show that quasi-trappedparticles are distributed along thecurrent sheet in such a way that theyconcentrate in the region with largevalues of normal magnetic fieldcomponent. As a result quasi-trappedions can dominate near the earthwardedge of TCS. In contrast, the electroncurrent becomes stronger in the TCStailward region where the normalmagnetic field component becomesweaker, and field line curvature drifts

are enhanced. Our quasi-adiabaticmodel predicts that thin current sheetsin the Earth’s magnetotail should haveweakly 2D configuration which,similar to its 1D analog consideredearlier, conserves the multiscale“matreshka” structure with multipleembedded layers.

The results of this work have beenpublished in H.V. Malova, V.Yu. Popov, D.C. Delcourt, A.A. Petrukovichand L.M. Zelenyi Antisunwardstructure of thin current sheets in theEarth’s magnetotail: implications ofquasi-adiabatic theory, J. Geophys.Res, VOL. 118, 4308–4318 (2013).

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The generation of a few-cycle opti-cal pulses and the broadband coherentsupercontinuum are the actual tasks ofthe modern optics. These techniquesplay a role in the development of thedata transmission systems, time-resol-ved spectroscopy, medical diagnos-tics, etc. The methods of the pulseparameters control by the dispersionproperties of the media could be usedin fundamental and applied aspects ofthe laser physics and nonlinear optics.The formation of the localized inspace and time high-power wavepacket with soliton-like propertieslight bullet is the most interest.

During the propagation in thetransparent medium, the intensefemtosecond pulse induces theformation of autended filament, thatcould be considered as a self-guidingsystem. The nonlinear process ofpulse propagation in such system issimilar to the pulse propagation inoptical fibers, photonic crystals andother guiding structures. So there arecommon regularities between theformation of solitons in nonlinearoptical structures with optimal modedispersion and the formation of lightbullets at the filamentation offemtosecond pulse in transparentdielectrics. Narrow filament with highlight intensity results from thedynamic balance of Kerr self-focusingand defocusing of the pulse in self-induced laser plasma. Together withKerr self-focusing, the pulse under-goes the compression that is due to theself-phase modulation. But in pre-sence of the self-phase modulation thedispersion starts playing a significantrole. In case of anomalous groupvelocity dispersion and the positiveself-phase modulation, the wavepacket continues to compress duringnonlinear propagation resulting in alight bullet formation. Such lightbullet could be considered as a

generalization of the time soliton in a1D+1 guiding structure on the 3D+1dimensions in transparent dielectric.

The physicists from the MSUnumerically predicted and clarifiedthe regularities of the light bulletssequence formation during 1800-nmpulse filamentation under anomalousGVD in fused silica. The peakintensity of light in the bullet reaches

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х10 W/cm , its duration is about ~10 fs and radius is ~ 10 μm.

Bas on the numerical prediction, the experimental registration ofthe light bullets sequence was performed in the Institute Spectroscopy RAS. The minimal light bulletduration reaches the value about twooptical cycles: 13.5 fs, that wasobtained from the autocorrelationmeasurements of the self-compressed1800-nm bullet formed during filamentation in the fused silica sample.

The appearance of the light bulletcorresponds to the sharp broadeningof the frequency-angular spectrum ofthe initial pulse. We predictednumerically and investigated experimentally the formation of theisolated anti-Stokes wing in thevisible region of the light bulletspectrum. [ , 38 (1), 16,(2013), ., 43, 326,(2013)].13 2

Optics LettersQuantum Electron

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LIGHT BULLETS ANDSUPERCONTINUUM SPECTRUMFROM FEMTOSECONDFILAMENT

The physicists from MSU numerically predicted and in collaboration with colleagues from the Institute of SpectroscopyRAS experimentally detected the light bullet formation at the filamentation of femtosecond laser pulses under anoma-lous group velocity dispersion in fused silica. [ , 38 (1), 16, (2013), 10, 105401(2013), ., 43, 326, (2013)].

Optics Letters Laser Physics LettersQuantum Electron

The schematic 3D images of the initialpulse intensity distribution and the form oflight bullet at the output plane of the fusedsilica sample.

The images of the conical emission ofsupercontinuum and spectra of super-continuum at the filamentation of 1300-nmpulse under zero group velocity dispersion;and of 1900-nm & 2100-nm pulses underanomalous group velocity dispersion, thatcorresponds to the light bullet formationand the anti-Stokes wing emission.

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The easiest way to describe atopological insulator is as an insulatorthat always has a metallic boundarywhen placed next to a vacuum or an'ordinary' insulator. These metallicboundaries originate from topologicalinvariants, which cannot change aslong as the material remains insulat-ing. The first topological insulator tobe discovered was the alloy Bi Sb ,

the unusual surface bands of whichwere mapped in an angle-resolvedp h o t o e m i s s i o n s p e c t r o s c o p y(ARPES) experiment. In ARPESexperiments, a high-energy photon isused to eject an electron from a crystal,and then the surface or bulk electronicstructure is determined from ananalysis of the momentum of theemitted electron. Although the surfacestructure of this alloy was found to becomplex, this investigation launched asearch for other topological insulators.

The search for topological insulators culminated in the recentdiscovery of topological insulatorbehaviour in Bi Se and Bi Te . These

'next-generation' materials both showtopological insulator behaviour up tohigher temperatures than does theoriginal material (Bi Sb ), with bulk

bandgaps of about 0.25 eV, and havethe simplest surface state that isallowed.

Fig. 1a shows the measured surfacestate of Bi Se and a theoretical

idealization of its state, including theelectron spin shown by blue arrows.Theoretical idealization of theelectronic structure of Bi Se , showing

the rotation of the spin degree offreedom (red arrows) as an electron(with energy E) moves around theFermi surface (with Fermi energy EF)is in fig. 1b. (J.E. Moore, 464,

2010). The surface state of the next-generation topological insulators isclosely related to the Dirac electronicstructure of graphene, which has alinear energy-momentum relationshiplike that of a relativistic particle (and isknown as a Dirac cone). Graphene,which consists of a single layer ofcarbon atoms, has been an extremelyactive subject of research in recentyears: it is interesting both structur-ally, because it is the most 2D materialpossible, and electronically, becauseof its linear energy-momentum rela-tionship. The main difference betweenthe surface of a topological insulatorand that of graphene is that thetopological insulator has only oneDirac point and no spin degeneracy,whereas graphene has two Diracpoints and shows spin degeneracy.This difference has far-reaching con-sequences, including the possibility ofgenerating new particles that haveapplications in quantum computing.

In the latest paper ( (2013)vol. 110, 136601) by the researcherfrom Faculty of Physics, MSU,together with his colleagues fromKorea, China, Japan and USAproposed a phase diagram for

Fe Bi Te (0 0.1 single crystals,

which belong to a class of magneti-cally bulk-doped topological insula-tors. The evolution of magneticcorrelations from ferromagnetic toantiferromagnetic gives rise totopological phase transitions, wherethe paramagnetic topological insu-lator of Bi Te turns into a band

insulator with ferromagnetic-clusterglassy behavior around ~0.025, and itfurther evolves to a topologicalinsulator with valence-bond glassybehavior, which spans over the regionfrom ~0.03 up to ~0.1. This phasediagram is verified by measuringmagnetization, magnetotransport, andangle-resolved photoemission spect-ra. Our experiments verified magneti-cally controlled topological phasetransitions by doping magnetic ionsinto topological insulators.

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Recearch highlights from the Faculty of PhysicsLomonosov Moscow State University /2013SCIENCE 2NEWSLETTER №The light bullet formation is

accompanied by plasma generation,that defocuses the pulse tail andprovides the shock-front formation.Sharp intensity gradient at the pulsetail causes the broadening of the blueside of pulse spectrum. So eachlight bullet formation occurs together with the "flash" emission of

short wavelength components and thespectrum of suprecont inuumbecomes asymmetrical. But duringthe light bullet propagation in thedispersive medium, the destructiveinterference of the spectral components leads to the formation of the dip,that separates the anti-Stokes wingfrom the central part of the spectrum.

The spectroscopic measurementswere performed in the Center of jointresearches, Institute SpectroscopyRAS using the IR correlometer ASF20 and IR spectrometer ASP-IRHSfrom Russian manufacturer "Avesta-Project".the

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Magnetic phase diagramof the topological insulator

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Vladimir Kulbachinskii

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Physicists from Moscow State Univ. in collaboration withresearchers from T8 NTS and Corning Inc. reached the record500 km unrepeatered 100 GB/s transmission.

Record 500 kmunrepeatered 100 GB/stransmission

In this work it was experimentallydemonstrated 500 km unrepeateredtransmission of a single-channel 100Gb s dual polarization quadraturephase shift keyed (DP-QPSK) signal.Such long distance transmission isachieved through the use of an advan-

ced configuration of remotely pumpedoptical amplifiers (ROPAs), chro-matic dispersion precompensationand ultra-low-loss Corning SMF-28ULLoptical fiber. Excellent long-termbit error ratio (BER) performance isobserved. To the best of our know-

ledge this is the longest unrepeatered100 Gb s transmission reported todate.

The results of this work have beenpublished in ,Vol. 10, 075107 (2013).

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Laser Physics Letters

Filamentation of ultrashort laserpulses is one of the most excitingrecent discoveries in optical physics.As a physical phenomenon, it involvesa complex, strongly coupled spa-tiotemporal dynamics of optical fieldwaveforms in nonlinear, fast-ionizingmedia, giving rise to unique regimesof ultrafast electrodynamics. Thisregime of short-pulse propagation Thebalance between self-focusing andplasma self-defocusing makes thepulse propagate much longer than theRayleigh range with a very high inten-sity. It results in a dramatic enhance-ment of nonlinear processes occurringin the filamentation zone. Thisphenomenon enables high intensitypulse compression and efficientnonlinear wavelength conversion withgas media. In ultrafast optical science,laser filamentation finds growingapplications as a powerful techniqueof pulse compression, enabling thegeneration of high-peak-power car-rier-envelope-phase (CEP) stable few-cycle optical field waveforms within abroad frequency range from the deep

ultraviolet to the near- and mid-infrared. Apart from a large variety ofnew spatiotemporal nonlinear opticalphenomena, femtosecond filamentsopen new perspectives in manyimportant applications, such as remotespectroscopy of the atmosphere,triggering of high-voltage discharges,water condensation, terahertz emis-sion sources and others.

To date, experimental research onfemtosecond pulse filamentation hasbeen almost exclusively carried out atthe wavelength of 0.8 μm. Fem-tosecond filamentation with long-wavelength sources presents a daun-ting challenge because of the enhance-ment the critical power of self-focusing with the laser wavelength.Realization of femtosecond mid-IRfilamentation would allow one toovercome the shortcomings of thecurrent 0.8-μm technology. First, mid-IR supercontinua are needed to reachthe molecular fingerprint region(fundamental vibrational and rovi-brational transitions) above 2.5 μm.Second, the combination of a longer

wavelength and a high intensity wouldensure that tunneling is the predomi-nant ionization mechanism and wouldenhance the THz emission from thefilament. Finally, the higher criticalpower allows generating singlefilaments of energy up to 25 timeshigher than at 800 nm.

The joint research by physicistsfrom M.V. Lomonosov Moscow StateUniversity and Vienna University ofTechnology enable the first observa-tion of the mid-infrared laser fila-mentation phenomenon in atomic andmolecular gases. Highly efficientgeneration supercontinuum distribu-tion over the beam at the output of acell with (a) N and (b) O at p = 4atm

for an input pulse width of 80 fs and aninitial energy of 9 mJ. Of more thanthree-octave spanning spectral con-tinuum, covering the entire range fromUV to 5.5 μm, is demonstrated in ar-gon. In the molecular gases N and O ,

we find that the output supercon-tinuum spectra strongly contrast fromthat observed in argon by displaying aclear red-shift.

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First filamentation demonstrationof ultrashortlaser pulsesin the mid-IR

Joint research by physicists from M.V. Lomonosov Moscow State University and Vienna University of Technologyenable the first observation of the mid-infrared laser filamentation phenomenon.

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Recearch highlights from the Faculty of PhysicsLomonosov Moscow State University /2013SCIENCE 2NEWSLETTER №To understand the filamentation of

ultrashort mid-IR pulses, we performa 3D supercomputer numerical mo-deling on Chebyshev and Lomonosovsupercomputers at Moscow StateUniversity. Results of numericalmodeling of filamentation demon-strate good agreement with theexperiment and confirm experimentalobservations that efficient generation

of low order harmonics together withthe spectral broadening of thefundamental pulse is the main mecha-nism of ultra-broadband continuumgeneration in argon. We interpret thered-shift in nitrogen and oxygen asgoverned by enhanced Raman effect,enabling highly efficient wavelengthdownshift of ultrashort pulses towardsmid-IR. More specifically, the

filamentation of 80 fs, 10 mJ laserpulses centered at 3.9 μm in N

generates a Raman-shifted millijoulesupercontinuum spanning from2.5 μm to 6 μm, while filamentation inoxygen yields over 65% conversionefficiency into the Stokes region.

This work has been published in38, 3194–3197 (2013).

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Optics Letters

Nodelesssuperconductivityin FeSe

Physicists from Moscow State Univ. in collaboration with the researchers from Switzerland made a revolutionary stepin creation of compact, stable generators of ultrashort laser pulses.

We investigate the temperaturedependence of the lower critical fieldH (T) of a high-quality FeSe single

crystal under static magnetic fields Hparallel to the c axis. The temperaturedependence of the first vortex pe-netration field has been experimen-tally obtained by two independentmethods and the correspondingH (T) was deduced by taking into

account demagnetization factors. Apronounced change in the H (T)

curvature is observed, which is

attributed to anisotopic s-wave ormultiband superconductivity. The

London penetration depth (T)

calculated from the lower criticalfield does not follow an exponentialbehavior at low temperatures, as itwould be expected for a fully gappedclean s-wave superconductor. Usingeither a two-band model with s-wave-

like gaps of magnitudes = 0.41 ±

0.1 meV and = 3.33 ± 0.25 meV or

a single anisotropic s-wave order

parameter, the temperature depend-ence of the lower critical field H (T)

can be well described. These obser-vations clearly show that the super-conducting energy gap in FeSe isnodeless.

The results of this work has beenpublished in: M. Abdel-Hafiez, J. Ge,A.N. Vasiliev, D.A. Chareev,J.Van de Vondel, V.V. Moschalkov,and A.V. Silhanek. ., B 88,174512 (2013).

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Physicists from Lomonosov Moscow State Univ. in collaboration with Natl Tsing Hua Univ. (Taiwan) demonstrated thatthe efficacy of laser energy transfer into the THz wave energy can increase with increasing the nonlinear periodicallypoled crystals even under the essential absorption of the THz radiation.

Optical parametric mixing is apopular scheme to generate an idlerwave at THz frequencies, althoughthe THz wave is often absorbing innonlinear optical material. It is widelysuggested that the useful materiallength for co-directional parametricmixing with strong THz-waveabsorption is comparable to the THz-wave absorption length in thematerial. Here we show that, even inthe limit of the absorption loss

exceeding parametric gain, the THzidler wave can grows monotonicallyfrom optical parametric amplificationover a much longer distance in anonlinear optical material until pumpdep-letion. The coherent productionof non- absorbing signal wave canassist the growth of the highlyabsorbing idler wave. We also showthat, for the case of an equal inputpump and signal in differencefrequency generation, the quick

saturation of the THz idler wavepredicted from a much simplified andyet popular plane-wave model failswhen fast diffraction of the THz wavefrom the co-propagating opticalmixing waves is considered.

The results of this study have beenpublished in , 21(2),2452 (2013) and in

, 10(5), 055404 (2013).

Optics ExpressLaser Physics

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Terahertz wave generation inperiodically polarized crystals

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Temporal solitonsin optical microresonators

Physicists from Moscow State Univ. in collaboration with researchers from Switzerland made a revolutionary step increation of compact, stable generators of ultrashort laser pulses.

Temporal dissipative solitons in acontinuous-wave laser-driven nonli-near optical microresonator wereobserved. The solitons were generatedspontaneously when the laser fre-quency was tuned through the effec-tive zero detuning point of a high-Qresonance, which led to an effectivered-detuned pumping. Transition tosoliton states were characterized bydiscontinuous steps in the resonatortransmission. The solitons were stablein the long term and their number

could be controlled via pump-laserdetuning. These observations are inagreement with numerical simulationsand soliton theory. Operating in thesingle-soliton regime allows thecontinuous output coupling of afemtosecond pulse train directly fromthe microresonator. This approachenables ultrashort pulse syntheses inspectral regimes in which broadbandlaser-gain media and saturableabsorbers are not available. In thefrequency domain the single-soliton

states correspond to low-noise opticalfrequency combs with smoothspectral envelopes, critical to appli-cations in broadband spectroscopy,telecommunications, astronomy andlow noise microwave generation.

The results of this work has beenpublished in: T. Herr, V. Brasch, J.D.Kost, C.Y.Wang, N.M.Kondratiev,M.L.Gorodetsky, and T.J.Kippenberg.

, December 2013(advance online publication).Nature Photonics

• Daria Daigen

• Denis Zotov

• Andrey Sviridov

•

•

•

Alexander Kurenkov

Anton Minnekhanov

Alexander Frolov

, "Development of a compact device fordiagnostics of nanomaterials for their suitability to be usedin photo-catalytic filters and gas sensors”

, "Sensor for complex study of live singlecells”

, "Setup for ultrasound diagnostics ofoncological

-;

;

tumors using silicon nanoparticles”;

, "High-precision convertors ofdisplacements based on the micro-size high-sensitivemagnetic field sensors”;

, "Development of multi-functioningrunning magneto optical sensor based on the surfaceplasmon resonance”;

, "Photocatalytic filter for aircleaning from tocsin impurities based on the alloyedtitanium dioxide”;

, "Femtosecond laser pulses convertorbased on the magnetoplasmonic crystals”.

• Ilya Mukha

Winners of the UMNIK-2013 competition

Section "Novel devices and apparatus”

• •Anna Kharlamova Olga Zhulyabina, "Production of novel "thick"amorphous microwires with the help of modifiedUlitovsky-T ilor method and monitoring of theirproperties”.

, "Cellular biochip for immune statusdetection".

a

Section "Novel Materials and Technologies” Section "Medicine of the Future”

AWARDS

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The final tour of the Recearch & Inovation Competition for young scientists took place on November 1st, 2013, at theFaculty of Physics, Lomonosov Moscow State University. This competition was organized by the Fund for supporting smallenterprises in research and innovations under support by the Federal Agency for Science &Innovations and the FederalAgency for Education of the Russian Federation. Each winner received up to 400000 rubles for two years. The jury selected25 winners this year, out of which 9 are from the Faculty of Physics Lomonosov Moscow State University.

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Evgeniya Smetanina

"Filament light bullets andtheir spectral characteristics"

, PhD

student of the Chair of GeneralPhysics and Wave Processes, for her

work on

.

Evgeniya Smetanina studied boththeoretically and experimentally thedynamics of space-time compressionof a powerful femtosecond laserradiation and the laws of high-powerlight bullets formation with the pulseduration of a few periods of the lightwave were revealed, as well as the

laws of broadband coherent supercon-tinuum generation due to the filamen-tation of the laser radiation in dielec-tric media. Possible practical applica-tions of the results of Evgenya's workare the time-resolved spectroscopy ofultrafast processes in molecular com-pounds and in biological molecules,time-resolved probing and ecologicalmonitoring of the environment.

Petr Yuldashev

"Medical and aero-acoustic applications of high ampli-tude acoustic waves with rapturedacoustic waves"

, researcher with

the Chair of General Physics and

Condensed Mater Physics, for his

work on

.

Petr Yuldashev studied nonlinearand diffraction wave effects that occurat propagation of acoustic waves withraptures in inhomogeneous media,focusing and reflection from theborders. This research is initiated bythe novel medical applications, whichuse raptured waves, such as extra-corporal shock-wave therapy andnoninvasive ultrasound surgery,which destroys the oncological tissueswith the help of a powerful focusedultrasound beam. Similar problemsare also under the active study, if oneanalyzes the problems of aero-acoustics the ecological sequences ofthe propagation of the powerful shockwave and powerful nonaeroacousticalnoise in the atmosphere in connectionwith the engineering of the newgenerations of the ultrasound air-liners.

The Science Contest for the young scientists of the Faculty of Physics was organized in November, 2013. It wasdevoted to the 80th-anniversary of the Faculty of Physics. As a result, 6 best research works submitted to the contestwere selected as the winners of the I to III degree.

Science contest for young scientistsof the Faculty of Physics

First degree diploma were awarded to:

• Irina Kolmychek

• Elena Popova

, Assistant Professor with the Chair ofGeneral Physics, for her work on "Generation ofmagnetoinduced second harmonic in magneticnanostructures and thin films";

, researcher with the Chair of Mathematics,for her work on "Modeling of the solar magnetic activity".

• Vladimir Zverev

• Yulia Ryzhikova

, postdoc with the Chair of GeneralPhysics and Condensed Matter, for his work on "Magneto-thermal properties of the heavy rare-Earth metals in theregion of magnetic phase transitions";

, researcher with the Chair of Optics andSpectroscopy, for her work on "Novel opportunities forimproving characteristics of the optical systems anddiagnostic tools".

Second degree diploma were awarded to: Third degree diploma were awarded to:

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Prof. , Academician, head of the chair of Astrophysics and Astronomy with theFaculty of Physics, and director of the Sternberg Astronomical Institute, Lomonosov Moscow State University, receivedthe 2013 Russian Government award in the field of education "for the development of innovative educational centerMoscow Planetarium that serves for popularization of research and implementation the effective education technologies".

Anatoly M. Cherepaschuk

Prof. , head of the chair of General Physicswith the Faculty of Physics, Lomonosov Moscow State University, received anorder "For merits before Fatherland" of the I degree given by the decree No 760 of4th of October 2013 of the Russian President for "the achievements in educationand many years of fruitful activity".

Alexander M. Saletskii

Prof. , head of the chair of LowTemperatures and Superconductivity with the Faculty of Physics,Lomonosov Moscow State University, was awarded the 2013 Lomonosovaward of the II degree for research for the series of his work on "Quantumbasic states of the matter: superconductivity and magnetism – unity andconflict of opposites".

Alexander N. Vasiliev

Associate Prof. , chair of Mathematics withthe Faculty of Physics, Lomonosov Moscow State University, was awarded the2013 Lomonosov award for education.

Alexander A. Shishkin

Congratulations to all the awardees!

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In May 2013,

, Associate Professor of

the Department of General Physicsand Wave Processes, defended his

Dr.Sci. thesis on

The thesis analyses polarizationnonlinear optical phenomena, causedby the dependence of nonlinearresponse of the medium on the state ofpolarization of light waves interacting

with it. This constitutes one of themain parts of wave optics and thesephenomena serve as the basis forpractical techniques for the study ofvarious substances.

The new phenomena studied in thepresent work are related to differentspectral ranges of electromagneticradiation: from UV to far IR. It is forthe first time that various nonlinearoptical and polarization effects ofterahertz (THz) frequency range havebeen analyzed. Active application ofTHz radiation was limited by theabsence of appropriate laboratoryequiment for its generation andregistration. The appearance of widelyavailable sources of ultrashort femto-second pulses led to a new direction ofresearch in THz frequency rangeclosely connected with laser physics,— THz pulse spectroscopy and THzspectrochronography.

Along with other promisingapplications, THz pulse radiation iswidely used in semiconductor andnanotechnologies, crystallographyand molecular spectroscopy. Unlikevisible light and near IR spectroscopy,which study the main electrontransitions and vibrations connectedwith intramolecular movements andintermolecular vibrations, THz fre-quency spectral response often pro-vides information about low-fre-

quency molecule vibrations, slowmotion of molecular groups andcollective excitation of phonon type inthe solid state phase.

THz pulse spectroscopy suggestsgeneration and simultaneous detectionof broadband radiation. At the sametime spectral information received bythe researcher is analogous to thatreceived using IR Fourier-spectrosco-py. The main difference and specificfeature of this method is the opportu-nity to simultaneously get dependen-cies of spectral dispersion of indica-tors of absorption and refraction forthe studied substances. Due to the factthat temporal response for spectralanalysis in pulse spectroscopy isprimary when this substance goesthrough electromagnetic field pulse ofsubpicosecond duration, the analysisof temporal profile of the field at thetime of passing through a substance,also bears information about thedynamics of vibrational, rotational andrelaxation processes taking placeunder the action of electromagneticfield pulse. The study of the temporaldynamics of THz field pulse forms thebasis for the development of THzspectroscopy technique with timeresolution, which is analogous to themethod of spectrochronography.

AlexanderShkurinov

"Temperaturedynamics of polarizationsensitive nonlinear mediaresponse under the interac-tion of ultrashort laser pulseswith molecules in the bulk andon the surface".

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DISSERTATIONS

Yuri.A. Koksharov"Electron magnetic reso-

nance in heterogeneous sys-tems with reduced dimensio-nality"

This Dr. Sci. dissertation is devotedto studying of various types of nano-particles, quasi-two-dimensionalcrystals, conjugated polymers andultrathin films by the electronmagnetic resonance (EMR) spectros-copy. Diversity of objects of researchrequires careful consideration ofEMR signals, which are very mani-fold qualitatively (paramagnetic,ferro-magnetic, superparamagneticsignals were studied) and quantita-tively (the linewidth variation comesup three orders of magnitude). Thegeneral attribute of all investigatedsystems is sufficient lack of homoge-neity of chemical composition, crystaland agnetic structures, morphologyetc.

Considerable effort was expendedto develop computer methods toanalyse various signs of differenttypes of heterogeneity in EMRspectra. Our experimental data showstrong sensitivity of EMR spectra tochemical inhomogeneity of magneticnanoparticles, temperature EMRanomalies in ferromagnetic nano-particles, unusual relaxation proper-ties of EMR centers in paramagneticnanoparticles and conjugated po-lymers. Some low-dimensionalantiferromagnetic systems can besuccessfully studied by the method of"natural spin probes" as proved inexperiments on goethite nano-particles, HTSC, and related systems.In conclusion, the dissertationestablishes some important classes ofinterconnection between structuraland EMR features of various hetero-geneous systems with reduceddimensionality.

In march 2013 associate professor

defended doctor of science thesison

This thesis is devoted to the physicsof magnetoelectric phenomena that isa rapidly developing field in con-densed matter science. In contrast tothe textbook electromagnetism, themagnetoelectricity describes thecoupling of static magnetism andelectricity: the constant electric fieldgives rise to the magnetization whilethe constant magnetic field induceselectric polarization in the magneto-electric media. Multiferroics, i.e.media with coexisting magnetic andelectric ordering also demonstratemagnetoelectric coupling.

In spite of the tempting possibilityof the magnetoelectric transformationwithout energy loss in spintronics andsensor technique these media are notwidely represented in technology dueto the scarcity of room temperaturemultiferroics. Therefore the motiva-tion of the study in the thesis was towiden this bottleneck of the magneto-

electric science with the new mecha-nisms of magnetoelectric coupling.

The plot of the thesis is based onthe uncovering of the unusual pro-perties of magnetic inhomogeneitiesand structures: spin spirals, domainwalls, magnetic vortices. The abovementioned objects are related to theflexomagnetoelectric effect, that canbe seen in the title of the thesis. It wasintroduced byA. Pyatakov by analogyto the flexoelectric effect in liquidcrystals (see Fig.) and was adopted byseveral groups throughout the worldto designate the class of magneto-electric phenomena related to themagnetic inhomogeneities. Theexperimental and theoretical study ofthe effect enables A. Pyatakov tocontrol magnetic domain walls withelectric field and to enhance theproperties of high temperaturemultiferroics that is of practicalinterest for spintronics applications.

Alexander P. Pyatakov

"Magnetoelectric and fle-xo-magnetoelectric effects inmultiferroics and magneticdielectrics".

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Fig. Flexoelectric effect, i.e. the emergent electric polarization due to: a) strain gradient in dielectric crystalsb) fan-shaped molecular structures in nematic liquid crystals c) spin cycloid structures in magnetically ordered media.

a b c

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On February 14, 2013, an associateprofessor of Department of Photonics

and microwave physics

defended his doctoralthesis on

.

Research carried out in this thesis,is devoted to theoretical and experi-mental studies of the optical radiationinteraction with nanostructures whoseoptical properties can be modified byexternal influences: by magnetic fieldor by intense laser irradiation.Specially selected periodic structureof plasmonic and photonic crystalsleads to resonant phenomena, resul-ting in significant enhancing of optical

and magneto-optical effects in desiredwavelength range. This opens greatopportunities to create new opticalelements, in which various opticalradiation characteristics are modu-lated effectively with frequency up to1 THz.

One of Dr. Belotelov's main resultsis creation of novel nanostructuredmaterial — magnetic plasmonic crys-tal, which allows to control effectivelythe polarization and intensity of lightand plasmonic oscillations by meansof magnetic field or optical irradiation.This material is very promising forinformation technology. Its uniquefeature is possibility to work both inlong distance optical zone (withpropagating light) and near-fieldoptical zone (with localized waves —with plasmon-polaritons and withwaveguide modes).

In this thesis magneto-opticaleffects resonant amplification inmagnetic plasmonic crystals was firsttime investigated and theory for thisamplification was created. TransverseKerr effect resonant 10 -fold ampli-fication and Faraday effect resonant10-fold amplification in comparisonwith magnetic films without plasmo-

nic layer were demonstrated.In addition, a magneto-optical

intensity effect was predicted andexperimentally demonstrated. Thiseffect arises in plasmonic crystals onaccount of waveguide modes excita-tion in meridionally magnetizedwaveguiding layer, i.e. it magnetizedin the film plane and along the wave-guide mode propagation direction.

The theory of Faraday effect andother magneto-optical effect resonantamplification in magnetic photoniccrystals was created and analyticalexpressions for Faraday angle wereobtained. These expressions agreewell with experimental data. Inversetransverse Kerr effect was theoreti-cally predicted.

Transmission and reflection coeffi-cients control as well as surfaceplasmon-polariton in plasmonic crys-tal control were first time demon-strated using femtosecond laser pulse(pulse energy density ~ 500 mkJ/cm ).Also the plasmon resonance modula-tion in plasmonic crystal was experi-mentally obtained using subsurfaceacoustic wave pulse at frequencies upto 110 GHz.

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VladimirBelotelov

"Plasmonic heterostructuresand photonic crystals withtunable optical properties"

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In the Fall of 2013, under umbrellaof the joint program "Moscow State tothe Schools" between the LomonosovMoscow State University and theDepartment of Education of theMoscow City Hall, the Faculty ofPhysics organized a series of events,of which the most significant was theLectures on Physics. Its programconsisted of 12 lectures under thefollowing three directions:

Series of 5 lectures "Real Physics"is targeted at the experimentaldemonstrations in various fields ofPhysics, which help attendees to meetwith a broad range of physicalphenomena and discover many new,

interesting and unusual manifestationof the physical laws;

Series of 5 popular sciencelectures "Portrait of Modern Physics"is targeted at the hot news and cutting-edge research in physics of elemen-tary particles, cosmology, biophysics,nanophysics, etc.;

Two master-classes on usingexperimental physical demonstrationsin teaching of Physics that weremainly targeted at the teachers, thoughit attracted quite a bit of schoolboys.

Lectures were organized everyweek, in the period of September 13thto November 29th, in the main PhysicsHall. Over 100 physical experimental

demonstrations were made during theseries of lectures in preparation ofwhich took part 26 faculty members.Besides these lectures, a specialmethodological booklet on usingexperiments in the teaching of Physicswas publlished and distributed amongthe teachers attending these lectures.

The Lectures on Physics raised agreat interest in Moscow. Mostpopular were the lectures under the"Real Physics" topic that regularlyattracted over 400 attendees! Thelecture "In the world of high voltage"also was cow TVchannels — TV-center and Moscow

filmed by two Mos-

24".

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•

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Lectures on Physicsfor the schoolboys and their teachers

On November 14 to 16, 2013,Physics Department of LomonosovMoscow State University hosted ameeting of the Presidium of theEducational-Methodological Unit(EMU) on Physics of the classicaluniversity education in connectionwith the 80th anniversary of theFaculty. More than 30 deans of thefaculties of physics from allover

Russia took part in this meeting.The meeting discussed the issues

of practical implementation of theLaw on Education, on a new graduate-level education, participation in theInternational Conferences on Phy-sical Education, etc. All the parti-cipants of this meeting took part in the80th anniversary commemorativemeeting where the warmly congra-

tulated the dean of the Faculty, staffmembers, and the students of theFaculty of Physics, LomonosovMoscow State University. They alsostated in their greetings a great andfruitful work of the Faculty of Physicswho coordinates activities in the fieldof physical education within theRussian universities .

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Physics Department hosteda meetingof the Presidium of the Educational-Methodological Unit on Physics

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Sace-to-S

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FACE-TO-SCHOOL

Confe

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SCIENCEFaculty of Physics, Lomonosov Moscow State University

NEWSLETTER № 2 2013/

Edited by N.N. Sysoev, V.N. Zadkov, A.A. Fedyanin, N.B. BaranovaDesign typesetting by I.A. Silantyeva

Signed to print on 2014, 200 pcs.

Faculty of Physics, Lomonosov Moscow State University119991 Moscow,GSP-1, Leninskie Gory 1, str. 2

Printed from a computer layout by Moscow University Publishers


80th Anniversary of the Facultyof Physics

80th anniversary of physics - msu.rupulses using the spectral filter. such attosecond shock waves...

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