Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 26: Quantum Dots and Wires 5: Optics 2

HL 26.9: Vortrag

Donnerstag, 8. September 2022, 12:00–12:15, H32

Nuclear Spin Polarization by Electron Spin Mode Dragging in an Ensemble of (In,Ga)As Quantum Dots — •Eiko Evers¹, Nataliia E. Kopteva^1,2, Irina A. Yugova^2,3, Dmitri R. Yakovlev^1,4, Manfred Bayer¹, and Alex Greilich¹ — ¹Experimentelle Physik 2, TU Dortmund, 44221 Dortmund, Germany — ²Spin Optics Laboratory of St. Petersburg State University, 198504 St. Petersburg, Russia — ³St. Petersburg, Russia — ⁴St. Petersburg, Russia

The electron-nuclear spin system in singly charged (In,Ga)As quantum dots (QDs) promises to combine the efficient optical electron spin (ES) orientation with the long coherence time in the nuclear spin (NS) system [1]. To come closer to a state of large NS polarization, we synchronize an ensemble of QDs, inhomogeneous in size, g factor, and resident ES precession frequency in a transverse external field, to a laser with a pulse repetition frequency of 1 GHz. As a result, the ensemble of ESs is homogenized by focusing it on a single precession mode by nuclei-induced frequency focusing [2]. In a substantial external field range, the single mode is fixed by a simultaneous build-up of an anti-parallel Overhauser field B_N caused by the polarization of NSs. The Overhauser field achievable in each QD differs and leads to the surprising emergence of equally spaced ES precession components in the ensemble.

[1] D. Gangloff et al., Science 364, 62 (2019)

[2] A. Greilich et al., Science 317 1896 (2007)