Nuclear magnetization in gallium arsenide quantum dots at zero magnetic field.
Optical and electrical control of the nuclear spin system allows enhancing the sensitivity of NMR applications and spin-based information storage and processing. Dynamic nuclear polarization in semiconductors is commonly achieved in the presence of a stabilizing external magnetic field. Here we report efficient optical pumping of nuclear spins at zero magnetic field in strain-free GaAs quantum dots. The strong interaction of a single, optically injected electron spin with the nuclear spins acts as a stabilizing, effective magnetic field (Knight field) on the nuclei. We optically tune the Knight field amplitude and direction. In combination with a small transverse magnetic field, we are able to control the longitudinal and transverse components of the nuclear spin polarization in the absence of lattice strain--that is, in dots with strongly reduced static nuclear quadrupole effects, as reproduced by our model calculations.
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
G
G
Sallen
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
S
S
Kunz
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
T
T
Amand
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
L
L
Bouet
National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044, Japan.
T
T
Kuroda
National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044, Japan.
T
T
Mano
LPMC, Ecole Polytechnique, CNRS, 91128 Palaiseau, France.
D
D
Paget
CNRS Laboratoire de Photonique et de Nanostructures, Route de Nozay, 91460 Marcoussis, France.
O
O
Krebs
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
X
X
Marie
National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044, Japan.
K
K
Sakoda
Université de Toulouse, INSA-CNRS-UPS, LPCNO, 135 Avenue Rangueil, 31077 Toulouse, France.
B
B
Urbaszek