Prof.
Marc
Aßmann
Department of Physics, Technical University of Dortmund, Germany
Exciton-polaritons are mixed light-matter quasiparticles arising due to the strong coupling of photons and excitons inside a semiconductor microcavity. As they are composite bosons of low mass, they may form a macroscopically coherent non-equilibrium condensate at elevated temperatures [1], which led to fascinating demonstrations of superfluidity [2] and quantized vortices [3] in the solid state. The photons leaking from the cavity are a part of the polariton wave function. Thus, the properties of the polariton condensate, including its energy, spin, momentum and phase may be investigated by spectroscopic means.
Under non-resonant excitation, polaritons form spontaneously from free carriers and form a condensate that interacts with them. As polaritons are several orders of magnitude lighter than these carriers, the latter effectively form a static repulsive potential for the condensed polaritons. Spatially shaping the excitation beam then enables us to investigate polariton condensates in optically imprinted potential landscapes. We show how to utilize these potentials to create and control quantized vortices in the polariton condensate [4], opening up new perspectives in polaritonics. Finally, we investigate quantitative means to characterize the resourcefulness of the condensate in terms of its quantum coherence [5] and demonstrate how to measure them using real-time spectroscopy for in-situ determination of photon correlations and density matrices of light fields.
References
1. J. Kasprzak et al., Nature 443, 409 (2006).
2. A. Amo et al., Nat. Phys. 5, 805 (2009).
3. K.G. Lagoudakis et al., Nat. Phys. 4, 706 (2008).
4. X. Ma et al., Nat. Comm. 11, 897 (2020).
5. C. Lüders et a., PRX Quantum 2, 030320 (2021).
This is a hybrid event:
Room D, the Institute of Physics PAS, Al. Lotników 32/46
Online: Zoom Link, (Passcode: 134595, Meeting ID: 823 8038 0442)
