Optically excited two-dimensional nanostructures are uniquely suitable for exploring and actively manipulating nonequilibrium states of interacting matter. I will illustrate such phenomena on the example of two systems. One is a bilayer populated by indirect excitons (IXs) —bound pairs of electrons and holes residing in opposite layers. These atom-like bosonic particles exhibit strong dipolar interaction with external electric field and with one another. I will overview our studies of IXs in potential energy landscapes, in particular, 1D periodic lattices created and controlled by voltage. I with also briefly discuss our ongoing experimental quest for high-temperature condensates of IXs in novel atomically thin heterostructures. The other system I will talk about is a “relativistic” electron-hole plasma created by femtosecond laser pulses in graphene. We have observed switching and time-dependent spectra of the collective modes of this plasma. We propose that the loss compensation or amplification of the modes —plasmons and yet to be discovered demons—may occur during the natural relaxation of graphene to equilibrium.
M.M. Fogler, L.V. Butov, K.S. Novoselov, Indirect excitons in van der Waals heterostructures, Nature Commun. 5, 4555 (2014).
M. Remeika, J. R. Leonard, C. J. Dorow, M. M. Fogler, L. V. Butov, M. Hanson, and A. C. Gossard, Measurement of exciton correlations using electrostatic lattices, Phys. Rev. B 92, 115311 (2015).
E.V. Calman, C.J. Dorow, M.M. Fogler, L.V. Butov, S. Hu, A. Mishchenko, A.K. Geim, Control of excitons in multi-layer van der Waals heterostructures, Appl. Phys. Lett. 108, 101901 (2016).
G. X. Ni, L. Wang, M. D. Goldflam, M. Wagner, Z. Fei, A. S. McLeod, M. K. Liu, F. Keilmann, B. Özyilmaz, A. H. Castro Neto, J. Hone, M. M. Fogler, and D. N. Basov, Ultrafast optical switching of infrared plasmon polaritons in high-mobility graphene, Nature Photonics 10, 244–247 (2016).
Zhiyuan Sun, D.¿N. Basov, and M.¿M. Fogler, Adiabatic amplification of plasmons and demons in 2D systems, Phys. Rev. Lett. 117, 076805 (2016).
Note: The talk will be held at 5pm to accommodate the ITAMP workshops. There will be no 10 minute talk.