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Institute for Theoretical Condensed Matter physics

Karlsruhe Institute of Technology

Wolfgang-Gaede-Str. 1
D-76131 Karlsruhe

Phone: +49 721 608-43367
Fax: +49 721608-47779

http://www.tkm.kit.edu/

Dynamics, synchronization, and quantum phase transitions of two dissipative spins

Dynamics, synchronization, and quantum phase transitions of two dissipative spins
Author:

Peter P. Orth, David Roosen, Walter Hofstetter, Karyn Le Hur

Source:

Phys. Rev. B 82, 144423 (2010)

selected as an Editors' Suggestion

We analyze the static and dynamic properties of two Ising-coupled quantum spins embedded in a common bosonic bath as an archetype of dissipative quantum mechanics. First, we elucidate the ground-state phase diagram for an Ohmic and a sub-Ohmic bath using a combination of bosonic numerical renormalization group (NRG), analytical techniques, and intuitive arguments. Second, by employing the time-dependent NRG we investigate the system’s rich dynamical behavior arising from the complex interplay between spin-spin and spin-bath interactions. Interestingly, spin oscillations can synchronize due to the proximity of the common non-Markovian bath and the system displays highly entangled steady states for certain nonequilibrium initial preparations. We complement our nonperturbative numerical results by exact analytical solutions when available and provide quantitative limits on the applicability of the perturbative Bloch-Redfield approach at weak coupling.