In the field of quantum dot optics, the exploitation of nonlinear processes remained so far limited to the coherent control of population and to the resonant 2-photon excitation of biexcitons. With our current work we have pioneered a new concept, which enables the control of single photon emission by a nonlinear down-conversion process. Starting from a biexciton state lB>, a tunable control laser field defines a virtual state in a stimulated process (SDC). From there, spontaneous emission to the ground state lG> leads to optically controlled single photon emission. Based on this concept, the energy and polarization of the single photon emission can be controlled in a complementary way by a classical laser field. The results lay the foundations for a new generation of nonlinear optical devices based on quantum optical principles.
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B. Jonas, D. Heinze, E. Schöll, P. Kallert, T. Langer, S. Krehs, A. Widhalm, K.D. Jöns, D. Reuter, S. Schumacher, A. Zrenner, Nature Communications (2022), 13(1), 1387