Authors: Gräßer, Timo
Rezai, Kristine
Sushkov, Alexander O.
Uhrig, Götz S.
Title: Understanding the dynamics of randomly positioned dipolar spin ensembles
Language (ISO): en
Abstract: Dipolar spin ensembles with random spin positions are attracting much attention because they help us to understand decoherence as it occurs in solid-state quantum bits in contact with spin baths. Also, these ensembles are systems which may show many-body localization, at least in the sense of very slow spin dynamics. We present measurements of the autocorrelations of spins on diamond surfaces at infinite temperature in a doubly rotating frame which eliminates local disorder. Strikingly, the timescales in the longitudinal and the transversal channel differ by more than one order of magnitude, which is a factor much greater than one would have expected from simulations of spins on lattices. A previously developed dynamic mean-field theory for spins (spinDMFT) fails to explain this phenomenon. Thus, we improve it by extending it to clusters (CspinDMFT). This theory does capture the striking mismatch up to two orders of magnitude for random ensembles. Without positional disorder, however, the mismatch is only moderate with a factor below 4. The pivotal role of positional disorder suggests that the strong mismatch is linked to precursors of many-body localization.
Subject Headings: Many-body localization
Spin dynamics
Random & disordered media
Mean field theory
Spin lattice models
Subject Headings (RSWK): Quantenmechanisches System
Spindynamik
Dynamische Molekularfeldtheorie
Spinmodell
URI: http://hdl.handle.net/2003/42249
http://dx.doi.org/10.17877/DE290R-24086
Issue Date: 2023-12-01
Rights link: https://creativecommons.org/licenses/by/4.0/
Appears in Collections:Theoretische Physik I

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