Inżynieria Nanostruktur - nowy makrokierunek na Uniwersytecie Warszawskim

Szkoła Inżynierii Nanostruktur
Molecular spintronics: from magnetic molecules to hybrid materials and multifunctional devices PDF Drukuj Email
Wpisany przez Jacek Szczytko   
poniedziałek, 09 listopada 2015 20:25

Eugenio Coronado Miralles

University of Valencia Institute of Molecular Science

Szkoła IN :  Monday 23th of November 2015, g. 15:15-17:00, room 1.40, Pasteura 5, Faculty of Physics University of Warsaw

Spin-based electronics is one of the emerging branches in today’s nanotechnology and the most active area within nanomagnetism. So far spintronics has been based on conventional materials like inorganic metals and semiconductors. A current trend in this area is that of incorporating molecules in the game. The resulting emergent field - namely molecular spintronics - is propelled by the possibility of preparing a second generation of spintronic devices based on molecular materials (organic spintronics), and by the possibility to manipulate the molecular spin individually (single-molecule nanospintronics). In this talk these two trends will be illustrated with several examples taken from my own research: i) the use of single-molecule nanomagnets as spin qubits [1]; ii) The electrical addressing of the spin in molecular nanoobjects [2]; iii) The use of single-molecule magnets based on rare-earths as components of new spin valves [3]; iv) the fabrication of spin-OLEDs (i.e., multifunctional molecular devices in which the light emission can be tuned through a
magnetic field).

Poprawiony: środa, 09 grudnia 2015 21:54
Sub-THz Ultrastrong light-matter coupling with Landau levels in semiconductors and superconducting metasurfaces PDF Drukuj Email
Wpisany przez Jacek Szczytko   
poniedziałek, 09 listopada 2015 20:14

Giacomo Scalari

ETH Zürich, Institute of Quantum Electronics, Auguste-­Piccard-Hof 1, Zürich 8093, Switzerland

Szkoła IN :  Friday 20th of November 2015, g. 10:15-12:00, room 0.06, Pasteura 5, Faculty of Physics University of Warsaw

Cavity light-matter coupling in solid state systems has been recently approaching the ultrastrong coupling regime [1-4], where the Rabi frequency Ω is comparable to the bare excitation frequency ω.. We recently demonstrated a new platform to investigate ultrastrong coupling physics: the cyclotron transition of a 2DEG is coupled to an Au metasurface of THz split-ring resonators reaching the ultrastrong coupling regime and showing record high values of the light-matter coupling ratio Ω / ω =0.58 [5]. I will present our recent advances in this polaritonic system. We employ Nb-based superconducting complementary metasurfaces [6] achieving adiabatic modulation of the polaritonic states through temperature tuning. With the same kind of cavities and a sample with n=4 quantum wells we observe a record‐high normalized coupling ratio of Ω / ω =0.89 [7] at a frequency of 300 GHz. For such value the polaritonic dispersion clearly deviates from the linear regime. I will discuss also an high quality factor complementary THz metasurface based on Niobium thin film [8], whch displays narrow resonance and Q factor higher than 50 at T=3 K in a strongly subwavelength volume ( Vcav/lambda3 of the order of 10-6 ). I will present new experimental results obtained measuring these metasurfaces at temperatures as low as 20 mK, where Q factors as high as 120 are measured. Our measurements highlight the role of the residual normal state electrons at temperatures well below the critical temperature TC

Poprawiony: środa, 09 grudnia 2015 21:54
Theory of polariton condensation PDF Drukuj Email
Wpisany przez Jacek Szczytko   
poniedziałek, 09 listopada 2015 19:06

Michiel Wouters

University of Antwerp

Szkoła IN :  Thursday 12 of November 2015, g. 12:15-14:00, room 3.73, Pasteura 5, Faculty of Physics University of Warsaw

Microcavity polaritons form a hybrid light-matter system that is under active experimental and theoretical investigation as a platform for quantum fluids.

In this talk, I will review the theoretical description of microcavity polaritons based on generalisations of the Gross-Pitaevskii equation and Bogoliubov theory. Both resonant, parametric and nonresonant excitation will be addressed. These descriptions allow to describe features such as the excitation spectrum, superfluidity, spatio-temporal coherence and nonequilibrium effects. Because of the nonequilibrium situation, microcavity polariton condensates can sustain flows in their steady state, which has led to the observation of quantized vortices.

Poprawiony: środa, 18 listopada 2015 21:23
Prof. Marian Grynberg - prekursor badań w zakresie THz PDF Drukuj Email
Wpisany przez Jacek Szczytko   
czwartek, 05 listopada 2015 21:54
Serdecznie zapraszamy na specjalne uroczyste Seminarium Fizyki Ciała Stałego, sala 0.06, ul. Pasteura 5,  2015-11-06 (10:15) poświęcone pracy naukowej prof. Mariana Grynberga. Prelegentami będą dr hab. Andrzej Witowski, prof. Roman Stępniewski, dr Gerard Martinez, prof. Wojciech Knap (IFD UW; High Magnetic Field Laboratory, Grenoble;University of Montpellier 2)

Szkoła odbywa się dzięki wsparciu projektu POKL UDA – POKL.04.01.01-00-100/10 "Chemia, fizyka i biologia na potrzeby społeczeństwa XXI wieku: nowe makrokierunki studiów I, II i III stopnia" prowadzonemu na Wydziale Chemii UW.

Poprawiony: poniedziałek, 09 listopada 2015 19:06
All-optical polariton-condensate devices PDF Drukuj Email
Wpisany przez Jacek Szczytko   
czwartek, 08 października 2015 18:54

Prof. Dr. Luis Viña

Departamento de Física de Materiales. Universidad Autónoma de Madrid. SPAIN

Szkoła IN :  Friday 16 of October 2015, g. 10:00-12:00, room 0.06, Pasteura 5, Faculty of Physics University of Warsaw

The use of polariton condensates in all optical logic devices has been the subject of intense research in recent years, promising ultrafast switching times, low losses, spin information transport and low power consumption.

In this talk I report on the realization of a novel switches and a logic AND gate mediated by propagating Bose-Einstein exciton-polariton condensate bullets in a quasi-1D semiconductor microcavity. I will also show how spin-selective spatial filtering of these propagating condensates can be achieved using a controllable spin-dependent gating barrier: a non-resonant laser beam provides the source of propagating polaritons, while a second circularly polarized weak beam imprints a spin dependent potential barrier, which gates the polariton flow and generates polariton spin currents. A complete spin-based control over the blocked and transmitted polaritons is obtained by varying the gate polarization.

The experimental results are interpreted in the light of simulations based on a generalized Gross-Pitaevskii equation.

Poprawiony: sobota, 31 października 2015 12:14
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