Optical evaluation of electron and hole g ‐factors in single quantum dots

Abstract

Precise optical evaluation of electron and hole g ‐factors in single InAlAs quantum dot was performed by using the optical pumping of nuclear magnetic field and its bistable behavior. The measurement is based on the fact that the induced nuclear field is effective only on electrons and can compensate the external magnetic field. The experimental results indicate that the effective electron g ‐factor can change in large magnitude including the sign in a controllable manner. Therefore, the method will be useful for the spin manipulation experiments such as photon‐spin qubit conversion. In addition, the in‐plane electron and hole g ‐factors were measured in Voigt geometry. This is the first report of individual g ‐factors of electron and hole in single InAlAs/AlGaAs quantum dots, which have been reported so far by only a few studies about the exciton g ‐factor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Direct observation of nuclear field fluctuations in single quantum dots

“…Regardless of the nominally undoped sample we used, the PL spectra from the various charge states that originated from the same single QD were observed. By using a variety of methods, e.g., from the exciton fine-structure measurements, 19 magneto-PL measurements under transverse magnetic fields, 20 the autocorrelation of PL, 21 and the binding energy consideration, 22 the charge states of three peaks with high intensities were assigned to a neutral biexciton (XX 0 ), a neutral exciton (X 0 ), and a positively charged exciton (X + ) from the lower energy side, respectively. In the lowest X + state composed of the spin-paired two holes and an electron, the spin-flipped electron gets the optically allowed transition and can recombine with a hole irrespective of its spin direction.…”

Nuclear spin depolarization via slow spin diffusion in single InAlAs quantum dots observed by using erase-pump-probe technique

“…Note that the horizontal energy axis is replotted from the midpoint of the two PL peaks of a neutral exciton. From the various measurements, 8,9,[13][14][15][16][17] the assignment of the spectral peaks could be achieved as follows: from the low energy side, a neutral biexciton (XX 0 ), a neutral exciton (X 0 ), and a positive trion (X þ ). In our QD sample, X þ PL was observed even at the minimum excitation power in the case of the wetting layer excitation.…”