title: Qubit protection in nuclear-spin quantum dot memories.
abstract: We present a mechanism to protect quantum information stored in an ensemble of nuclear spins in a semiconductor quantum dot. When the dot is charged the nuclei interact with the spin of the excess electron through the hyperfine coupling. If this coupling is made off-resonant, it leads to an energy gap between the collective storage states and all other states. We show that the energy gap protects the quantum memory from local spin-flip and spin-dephasing noise. Effects of nonperfect initial spin polarization and inhomogeneous hyperfine coupling are discussed.
authors: Fachbereich Physik, University of Kaiserslautern, D-67663 Kaiserslautern, Germany.
authors: Z
authors: Z
authors: Kurucz
authors: M W
authors: MW
authors: Sørensen
authors: J M
authors: JM
authors: Taylor
authors: M D
authors: MD
authors: Lukin
authors: M
authors: M
authors: Fleischhauer