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Persistent dark states in anisotropic central spin models.

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Villazon, Tamiro 
Claeys, Pieter W 
Pandey, Mohit 
Polkovnikov, Anatoli 
Chandran, Anushya 


Long-lived dark states, in which an experimentally accessible qubit is not in thermal equilibrium with a surrounding spin bath, are pervasive in solid-state systems. We explain the ubiquity of dark states in a large class of inhomogeneous central spin models using the proximity to integrable lines with exact dark eigenstates. At numerically accessible sizes, dark states persist as eigenstates at large deviations from integrability, and the qubit retains memory of its initial polarization at long times. Although the eigenstates of the system are chaotic, exhibiting exponential sensitivity to small perturbations, they do not satisfy the eigenstate thermalization hypothesis. Rather, we predict long relaxation times that increase exponentially with system size. We propose that this intermediate chaotic but non-ergodic regime characterizes mesoscopic quantum dot and diamond defect systems, as we see no numerical tendency towards conventional thermalization with a finite relaxation time.


Funder: Belgian American Educational Foundation; doi:

Funder: Francqui Foundation Fellowship

Funder: Banco Santander Boston University-National University of Singapore grant

Funder: Sloan Research Fellowship


5108 Quantum Physics, 51 Physical Sciences

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Springer Science and Business Media LLC
Engineering and Physical Sciences Research Council (EP/P034616/1)