| Issue |
Europhys. Lett.
Volume 43, Number 2, July II 1998
|
|
|---|---|---|
| Page(s) | 117 - 122 | |
| Section | General | |
| DOI | https://doi.org/10.1209/epl/i1998-00328-9 | |
| Published online | 01 September 2002 | |
Decay of correlations in the dissipative two-state system
1
Institut für Theoretische Physik, Universität
Stuttgart - D-70550 Stuttgart, Germany
2
Istituto di Fisica, Università di Catania and INFM,
Viale A. Doria 6, 95129 Catania, Italy
Received:
9
March
1998
Accepted:
22
May
1998
We study the equilibrium correlation function of the polaron-dressed
tunnelling operator in the dissipative two-state system and compare the
asymptoptic dynamics with that of the position correlations.
For an Ohmic spectral density with damping strength
, the correlation functions are obtained in analytic form
for all times at any T and any bias.
For K<1, the asymptotic dynamics is found by using a diagrammatic approach
within a Coulomb gas representation. At T=0, the tunnelling or
coherence correlations drop as 
, whereas
the position correlations show universal decay 
.
The former decay law is a signature of unscreened attractive charge-charge
interactions, while the latter is due to unscreened dipole-dipole
interactions.
PACS: 05.30.-d – Quantum statistical mechanics / 05.40.+j – Fluctuation phenomena, random processes, and Brownian motion / 73.40.Gk – Tunneling
© EDP Sciences, 1998
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