The problem of how single "central" spins interact with a nuclear spin bath is essential for understanding decoherence and relaxation in many quantum systems, yet is highly nontrivial owing to the many-body couplings involved. Different models yield widely varying timescales and dynamical responses (exponential, power-law, Gaussian, etc). Here we detect the small random fluctuations of central spins in thermal equilibrium (holes in singly-charged (In,Ga)As quantum dots) to reveal the timescales and functional form of bath-induced spin relaxation. This spin noise indicates long (400 ns) spin correlation times at zero magnetic field, that increase to ∼5 μs as hole-nuclear coupling is suppressed with small (100 G) applied fields. Concomitantly, the noise lineshape evolves from Lorentzian to power-law, indicating a crossover from exponential to inverse-log dynamics.
@article{arxiv.1201.6619,
title = {Intrinsic spin fluctuations reveal the dynamical response function of holes coupled to nuclear spin baths in (In,Ga)As quantum dots},
author = {Yan Li and N. Sinitsyn and D. L. Smith and D. Reuter and A. D. Wieck and D. R. Yakovlev and M. Bayer and S. A. Crooker},
journal= {arXiv preprint arXiv:1201.6619},
year = {2012}
}
Comments
4 pages & 4 figures, + 8 pages supplemental material