Kurucz, ZSørensen, M WTaylor, JacobLukin, MikhailFleischhauer, M2011-11-152009Kurucz, Z., M.W. Sørensen, J.M. Taylor, M.D. Lukin, and M. Fleischhauer. 2009. Qubit protection in nuclear-spin quantum dot memories. Physical Review Letters 103(1): 010502.0031-9007http://nrs.harvard.edu/urn-3:HUL.InstRepos:5345668We 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 non-perfect initial spin polarization and inhomogeneous hyperfine coupling are discussed.en-USJournal Article2011-11-1510.1103/PhysRevLett.103.010502