Inżynieria Nanostruktur - nowy makrokierunek na Uniwersytecie Warszawskim

Strona główna Szkoła Inżynierii Nanostruktur Sub-THz Ultrastrong light-matter coupling with Landau levels in semiconductors and superconducting metasurfaces
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

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[2] T. Niemczyk, F. Deppe, H. Huebl, E. P. Menzel, F. Hocke, M. J. Schwarz, J. J. Garcia-Ripoll, D. Zueco, T.
Hmmer, E. Solano, et al., Nature Physics 6, 772776 (2010).
[3] G. Günter et al., Nature 458, 178 (2009).
[4] Y. Todorov et al., Phys. Rev. Lett. 105, 196402 (2010).
[5| G. Scalari, C. Maissen, D. Turcinkova, D.Hagenmuller, S. deLiberato, C. Ciuti, C. Reichl, D.Schuh, W.
Wegscheider, M. Beck and J. Faist, Science 335, 1323 (2012)
[6] G. Scalari, C. Maissen, S. Cibella, R. Leoni, P. Carelli, F. Valmorra, M. Beck, and J. Faist, New Journal of
Physics 16, 033005 (2014).
[7] C. Maissen, G. Scalari, F. Valmorra, M. Beck, S. Cibella, R. Leoni, C. Reichl, C. Charpentier, W. Wegscheider,
J. Faist, Phys. Rev. B 90, 205309 (2014)
[8] G. Scalari et al., Applied Physics Letters 105 (26), 261104 (2014).

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: środa, 09 grudnia 2015 21:54