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arXiv · 0804.1457

Dynamics of large anisotropic spin in a sub-ohmic dissipative environment close to a quantum-phase transition

Frithjof B. Anders
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Abstract

We investigate the dynamics of a large anisotropic spin whose easy-axis component is coupled to a bosonic bath with a spectral function $J(\w)\propto ω^s$. Such a spin complex might be realized in a single-molecular magnet. Using the non-perturbative renormalization group, we calculate the line of quantum-phase transitions in the sub-ohmic regime ($s<1$). These quantum-phase transitions only occur for integer spin $J$. For half-integer $J$, the low temperature fixed-point is identical to the fixed-point of the spin-boson model without quantum-tunneling between the two levels. Short-time coherent oscillations in the spin decay prevail even into the localized phase in the sub-ohmic regime. The influence of the reorganization energy and the recurrence time on the decoherence in the absence of quantum-tunneling is discussed.

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Frithjof B. Anders. 2008-04-09. Dynamics of large anisotropic spin in a sub-ohmic dissipative environment close to a quantum-phase transition. https://doi.org/10.1088/1367-2630%2F10%2F11%2F115007

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