Scientific Council of the Landau Institute, Friday, December 13, 2019, Landau Institute, 11:30 am|
P.G. Grinevich, P.M. Santini
Effect of small dissipation on the NLS anomalous waves recurrence.
We provide analytic formulas decribing the effect of small loss/gain on the recurrence of anomalous waves in the focusing Nonlinear Schrodinger equation. We show that very small loss or gain essentially affects the statistics and the character of the recurrence. In particular, our formulas explains the results of numerical simulations from the paper by O. Kimmoun, H.C. Hsu, H. Branger, M.S. Li, Y.Y. Chen, C. Kharif, M. Onorato, E.J.R. Kelleher, B. Kibler, N. Akhmediev, A. Chabchoub (2016).
Department of quantum mesoscopics: seminar, Friday, December 13, 2019, ITF, 2:30 pm|
1. Ivan Tsitsilin (MISiS, RKTs)
Eksperimenty so sverkhprovodyashchimi kubitami
Razvitie tekhnologii proizvodstva i izmereniya sverkhprovodyashchikh kubitov v Rossii uzhe pozvolyaet sozdavat' mnogokubitnye svyazannye sistemy, iz kotorykh mozhno delat' razlichnye analogovye i tsifrovye simulyatory. Poluchennyi v sozdanii dvukhkubitnykh geitov opyt pokazal nam napravlenie dlya dal'neishego razvitiya v etoi sfere: kakie tipy geitov neobkhodimo ispol'zovat' i uluchshat', kak vyklyuchat' ostatochnoe ZZ vzaimodeistvie vo vremya prostaivaniya kubitov. Ya predstavlyu nashi rezul'taty i rasskazhu o potentsial'nykh sposobakh prodvizheniya v etikh oblastyakh.
Department of quantum mesoscopics: seminar, Friday, December 13, 2019, ITF, 3:30 pm|
2. Anton Khvalyuk
Obzor osnovnykh algoritmov kvantovykh simulyatsii
Iz-za apparatnykh ogranichenii sushchestvuyushchie kvantovye protsessory sposobny proizvodit' lish' opredelennyi nabor unitarnykh operatsii nad odnim ili dvumya kvantovymi bitami v techenie konechnogo promezhutka vremeni, posle kotorogo ustroistvo teryaet kogerentnost'. Chtoby ispol'zovat' podobnye ustroistva dlya simulyatsii proizvol'nogo vida gamil'tonianov, neobkhodimo stroit' priblizheniya, pozvolyayushchie s pomoshch'yu dostupnykh operatsii vosproizvesti proizvol'nyi operator evolyutsii i pri etom ispol'zuyushchie kak mozhno men'she obrashchenii k kvantovomu ustroistvu.
My razberem detali raboty kazhdogo iz predstavlennykh algoritmov, obsudim sushchestvuyushchie otsenki dlya ikh vremeni raboty i chisla ispol'zuemykh elementarnykh operatsii.
Laboratory building, room 122
Moscow Institute of Physics and Technology
contact e-mail address: email@example.com (head M.V.Feigel'man, deputy head I.V.Zagorodnev)Research topics
Department of quantum mesoscopics: seminar, Friday, November 29, 2019, ITF, 3:00 pm|
V.Kuznetsov (eksperimental'naya chast') i S.Dikman (teoreticheskaya chast')
Sovmestnyi doklad po rabote S.Dikmana, L.Kulika i V.Kuznetsova (IFTT)
"Coherence-decoherence transition in a spin-magnetoexcitonic ensemble in a quantum Hall system"
In the talk, we focus on the physics of magneto-excitons in a quantum
Hall insulator at the filling factor of 2. The simplest realizations are
magneto-excitons formed by an electron promoted from the occupied zeroth
Landau level to the empty first Landau level and by the vacancy under
the Fermi level. There are two magneto-excitons: a spin-singlet with
total spin S = 0; and a spin-triplet (CSFE) with total spin S = 1. The
first one is magneto-plasmon which decays with the emission of a photon.
In contrast, the CSFE is not radiatively active owing to electron spin
conservation and its energy is lower than the cyclotron energy.
Consequently, spin-triplet magneto-excitons exhibit relaxation time
reaching up to 900 us. We also discovered condensation of excitons by
measurement of exciton lifetime in a temperature range of 0.5–1.5 K.
Here we report on spin exciton transfer at distance exceeding 200 μm by
pump-probe photo-luminescence measurements and photo-resonant reflection.
These effects exhibit threshold both in excitation power and
Scientific Council of the Landau Institute, Friday, November 29, 2019, Landau Institute, 11:30 am|
Baerbel Rethfeld (Technische Universitaet Kaiserslautern, Germany)
Relaxation dynamics of nonequilibrium electrons in laser-excited solids
When an ultrashort laser pulse of visible light is absorbed by a solid, mainly the electrons in the material are excited. In metals, free electrons in the conduction band can directly absorb photons. In semiconductors and dielectrics, on the other hand, a band gap has to be overcome first, as almost no free electrons are present at room temperature in the unexcited material. Due to this excitation, the electronic system, or the so-called electron-hole plasma, is in a nonequilibrium state. A sequence of different relaxation processes transfers the material into a new equilibrium. Depending on the interaction associated with the particular relaxation process, it occurs on a characteristic timescale.
On the basis of complete Boltzmann-type collision integrals, we calculate the transient
distribution functions of electrons and phonons in different materials. We consider
electron-electron interaction, different ionization processes, as well as electron-phonon coupling. By that we trace the relaxation cascade of nonequilibrium electrons after ultrafast heating.
Distinct material properties enter through the density of states of the electrons in the
conduction band. We study in particular noble metals, dielectrics and ferromagnets. In
noble metals and ferromagnets, d-electrons play an important role, whereas in dielectrics two separated bands govern the dynamics and the ionization state may differ from. We show, that the electron distributions deviate from Fermi distributions for timescales up to a few picoseconds. While the initial thermalization within one band has an intrinsic timescale of typically only a few tens of femtoseconds, nonequilibrium occupations of the different bands as well as continous electron-phonon coupling can drive the conduction electrons out of equilibrium for much longer times [1, 2].
We present in detail the mutual influence of different interaction and relaxation processes.