Spin noise of electrons and holes in self-assembled quantum dots.
We measure the frequency spectra of random spin fluctuations, or "spin noise," in ensembles of (In,Ga)As/GaAs quantum dots (QDs) at low temperatures. We employ a spin noise spectrometer based on a sensitive optical Faraday rotation magnetometer that is coupled to a digitizer and field-programmable gate array, to measure and average noise spectra from 0-1 GHz continuously in real time with subnanoradian/sqrt[Hz] sensitivity. Both electron and hole spin fluctuations generate distinct noise peaks, whose shift and broadening with magnetic field directly reveal their g factors and dephasing rates within the ensemble. A large, energy-dependent anisotropy of the in-plane hole g factor is clearly exposed, reflecting systematic variations in the average QD confinement potential.
Crooker
S A
SA
National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545 USA. crooker@lanl.gov
Brandt
J
J
Sandfort
C
C
Greilich
A
A
Yakovlev
D R
DR
Reuter
D
D
Wieck
A D
AD
Bayer
M
M