Inżynieria Nanostruktur - nowy makrokierunek na Uniwersytecie Warszawskim

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).

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 ( V_cav/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 T_C

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.

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.