Abstract
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 time scales 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 time scales and functional form of bath-induced spin relaxation. This spin noise indicates long (400 ns) spin correlation times at a zero magnetic field that increase to as dominant hole-nuclear relaxation channels are suppressed with small (100 G) applied fields. Concomitantly, the noise line shape evolves from Lorentzian to power law, indicating a crossover from exponential to slow [] dynamics.
- Received 26 January 2012
DOI:https://doi.org/10.1103/PhysRevLett.108.186603
© 2012 American Physical Society
Synopsis
Listening to Spin Fluctuations
Published 3 May 2012
Spin-noise spectroscopy reveals a functional transition in the spin decay of quantum dots.
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