Optically pumped spin polarization as a probe of many-body thermalization

D. PAGLIERO; P.R. ZANGARA; J. HENSHAW; A. AJOY; ACOSTA, R.H.; J. REIMER; A. PINES; C.A. MERILES

Science Advances

AAAS

Año: 2020 vol. 6 p. 1 - 8

2375-2548

The interplay between disorder and transport is a problem central to the understanding of a broad range ofphysical processes, most notably the ability of a system to reach thermal equilibrium. Disorder and many-bodyinteractions are known to compete with the dominance of one or the other, giving rise to fundamentally differentdynamical phases. Here, we investigate the spin diffusion dynamics of 13C in diamond, which we dynamicallypolarize at room temperature via optical spin pumping of engineered color centers. We focus on low-abundance,strongly hyperfine-coupled nuclei, whose role in the polarization transport we expose through the integratedimpact of variable radio frequency excitation on the observable bulk 13C magnetic resonance signal. Unexpectedly,we find good thermal contact throughout the nuclear spin bath, virtually independent of the hyperfine couplingstrength, which we attribute to effective carbon-carbon interactions mediated by the electronic spin ensemble. Inparticular, observations across the full range of hyperfine couplings indicate that the nuclear spin diffusion constanttakes values up to two orders of magnitude greater than that expected from homonuclear spin couplings. Ourresults open intriguing opportunities to study the onset of thermalization in a system by controlling the internalinteractions within the bath.