Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 109: Quantum dots and wires: Quantum communication and quantum information science
HL 109.6: Talk
Friday, March 20, 2015, 12:30–12:45, ER 164
Coherent photocurrent spectroscopy of single InAs quantum dots at 1500 nm — •Simon Gordon1, Matusala Yacob2, Yves Alexander Leier1, Mohamed Benyoucef2, Johann Peter Reithmaier2, and Artur Zrenner1 — 1CeOPP, Universität Paderborn, Paderborn, Germany — 2INA, Universität Kassel, Kassel, Germany
For long distance quantum communication it is essential to use flying qubits in the telecom wavelength bands. Quantum emitters or detectors in this wavelength regime can be realized with InAs quantum dots on InP substrate. In this work, such InAs quantum dots are investigated by low-temperature photocurrent spectroscopy. Suitable p-i-n diode structures with self-assembled quantum dots have been grown by molecular beam epitaxy on InP(100) substrates. The layer sequence of the diodes consists of an n-InP back contact, an intrinsic region of lattice-matched InAlGaAs, which contains the quantum dots, and a p-InP front contact. The quantum dots are coherently excited by an optical parametric oscillator. By changing the applied reverse voltage the resonance energy of the quantum dot is tuned by the quantum confined Stark effect to the energy of the light pulse. Increasing the power of the excitation light pulses leads to a nonlinear response of the photocurrent. We observe a clear signature of Rabi oscillations. By measuring the photocurrent it is also possible to determine the occupancy of the two level quantum system after coherent excitation.