Physics Colloquium

Marco Polini, NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Pisa, Italy

"Hot carriers in graphene: a table-top 'quark-gluon soup'"

4:15pm, The John A. Wheeler Lecture Hall (RLM 4.102)

Coffee and cookies will be served at 4:00pm in RLM 4.102

Host: Prof. MacDonald

Abstract:

Theories of the evolution of the Universe after the Big Bang address a profound non-equilibrium problem which, in its early stages, involves an asymptotically free plasma of quarks and gluons. In this Colloquium, I will discuss some similarities and differences between the quark-gluon plasma (QGP) in early universe cosmology and a solid-state analogue created1 by shining laser light on a two-dimensional (2D) crystal of Carbon atoms: graphene. The interaction of light with graphene creates a highly non-equilibrium distribution of fermions, which are described by an ultrarelativistic 2D Dirac equation. These “hot” massless Dirac fermions interact both among themselves via the Coulomb force, and with a bath of bosons, the quantized lattice vibrations of the 2D crystal. I will demonstrate that the very early stages of the non-equilibrium dynamics of the graphene QGP are entirely controlled by carrier-carrier collinear Coulomb scattering processes including “carrier multiplication”. This effect could lead to improved photovoltaic and photodetector devices.

Bibliography

1D. Brida, A. Tomadin, C. Manzoni, Y.J. Kim, A. Lombardo, S. Milana, R.R. Nair, K.S. Novoselov, A.C. Ferrari, G. Cerullo, and M. Polini, Ultrafast collinear scattering and carrier multiplication in graphene, arXiv:1209.5729v1.