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

• Published in: Science advances Vol. 6; no. 18
• Main Authors: Pagliero, Daniela, Zangara, Pablo R., Henshaw, Jacob, Ajoy, Ashok, Acosta, Rodolfo H., Reimer, Jeffrey A., Pines, Alexander, Meriles, Carlos A.
• Format: Journal Article
• Language: English
• Published: United States AAAS 01-05-2020; American Association for the Advancement of Science
• Subjects: Applied Physics; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Physics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.aaz6986

Select nuclear spins in a solid isolated from the rest due to local fields reach equilibrium via multielectron spin interactions.
Disorder and many body interactions are known to impact transport and thermalization in competing ways, with the dominance of one or the other giving rise to fundamentally different dynamical phases. Here we investigate the spin diffusion dynamics of
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C in diamond, which we dynamically polarize 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 integrated impact of variable radio-frequency excitation on the observable bulk
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C magnetic resonance signal. Unexpectedly, we find good thermal contact throughout the nuclear spin bath, virtually independent of the hyperfine coupling strength, which we attribute to effective carbon-carbon interactions mediated by the electronic spin ensemble. In particular, observations across the full range of hyperfine couplings indicate the nuclear spin diffusion constant takes values up to two orders of magnitude greater than that expected from homo-nuclear spin couplings.