Design of a Rutherford-like scattering experiment in a semiconductor Dominik Niemietz 1 , Johannes Schmutzler 1 , Przemyslaw Lewandowski 2 , Marc Aßmann 1 , Stefan Schumacher 2 , Martin Kamp 3 , Christian Schneider 3 , Sven H ¨ ofling 4 and Manfred Bayer 1 1 Experimentelle Physik 2, Technische Universit¨ at Dortmund, D-44221 Dortmund, Germany 2 Department of Physics and CeOPP, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany 3 Technische Physik, Physikalisches Institut, Wilhelm Conrad R¨ ontgen Research Center for Complex Material Systems, Universit¨ at W¨ urzburg, D-97074 W¨ urzburg, Germany 4 SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom. Scattering experiments are an important tool in nuclear and high energy physics to gain insight into subatomic structures. In these experiments, the observed trajectories of the scattered particles allow for the reconstruction of the scattering potential. In condensed matter, however, typically the occurrence of scattering is rather indirectly determined, e. g. by the measurement of the phase coherence time. Very promising for the direct observation of scattering trajectories in condensed matter are exciton-polaritons in semiconductor microcavities, which can ballistically propagate over tens of microns and can easily be monitored due to their efficient coupling to the light field. So far, using a resonant excitation scheme, broad streams of polariton condensates were on target for barriers, typically one order of magnitude smaller compared to the propagating polariton condensate, to reveal the frictionless flow behavior of a superfluid polariton condensate.[1, 2] Here, we generate a directed flow of a polariton condensate by nonresonant excitation, which offers the benefit of a large degree of freedom regarding the choice of excitation angle and energy. The scattering potential is created by injection of background carriers by means of a nonresonant Gaussian laser spot. In addition, the height of the potential can be tailored by variation of the excitation power level. Our experimental approach provides the opportunity for a direct observation of trajectories of scattered polaritons (Figure 1, left panel). As a result, we observe a minimum scattering angle of 35 ◦ and a monotonous increase towards 60 ◦ with rising excitation power as depicted in figure 1, right panel. By means of this experimental approach, Rutherford-like scattering experiments can be performed in a semiconductor, which gives insight into the interaction strength between polaritons and background carriers. Figure 1: (left) Polariton condensate flow (right arm) scatters at background carriers created by a Gaussian laser spot with scattering angle α. (right) Dependency between scattering angle and excitation power of Gaussian spot. P thr is the threshold power for polariton condensation of the Gaussian laser spot. References [1] Amo, A., Lefrere, J., Pigeon, S., Adrados, C., Ciuti, C., Carusotto, I., Houdre, R., Giacobino, E., and Bramati, A. Nat. Phys. 5, 805–810 (2009). [2] Sanvitto, D., Pigeon, S., Amo, A., Ballarini, D., De Giorgi, M., Carusotto, I., Hivet, R., Pisanello, F., Sala, V. G., Guimaraes, P. S. S., Houdre, R., Giacobino, E., Ciuti, C., Bramati, A., and Gigli, G. Nat. Photon. 5, 610–614 (2011).