Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 9: Quantum dots: Optical properties

HL 9.7: Talk

Monday, March 16, 2015, 11:45–12:00, EW 203

Applying pump-probe quantum state tomography to a semiconductor optical amplifier — •Nicolai B. Grosse¹, Nina Owschimikow¹, Roland Aust², Benjamin Lingnau², Alexej Koltchanov¹, Mirko Kolarczik¹, Kathy Lüdge², and Ulrike Woggon¹ — ¹Institut für Optik und Atomare Physik, Technische Universität Berlin, Germany — ²Institut für Theoretische Physik, Technische Universität Berlin, Germany

We have combined the techniques of pump-probe and quantum state tomography to observe how an In(Ga)As based quantum-dot semiconductor optical amplifier can transform the quantum state of a probe pulse that is tuned to the quantum dots' ground state, while optically pumping the quantum dots' excited state. From the Wigner functions thus obtained, the device gain, the amplified noise, and the excess noise due to amplified spontaneous emission could be measured relative to the quantum noise limit and on an ultrafast time scale. This information was used to infer the degree of population inversion in the gain medium, which revealed a depletion and recovery of the population inversion on the sub-picosecond time scale.