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TT: Tiefe Temperaturen
TT 22: Quantenstörstellen und quantenkritische Ph
änomene
TT 22.3: Vortrag
Freitag, 26. März 1999, 10:30–10:45, F3
Thermodynamics of the Ohmic two-state system: exact solution via the Bethe-Ansatz — •T. Costi1 and G. Zaránd2 — 1Theoretische Physik III, Universität Augsburg — 2Instutute of Physics, Technical University of Budapest, Hungary
The thermodynamics of the Ohmic two-state system is calculated exactly for all temperatures and level asymmetries, ε, by exploiting the equivalence of the two-state system to the anisotropic Kondo model. The thermodynamic Bethe-Ansatz equations of the latter [1] are solved to give the universal scaling functions for the specific heat, Cα(T), and dielectric susceptibility, χα(T), of the former for all level asymmetries and dissipation strengths 0<α<1 [2]. The logarithmic corrections to these quantities at high temperatures are found in the Kondo limit α→ 1−, whereas for α< 1 we find the expected power law temperature dependences with the powers being functions of the dissipative coupling α. The low temperature behaviour is always that of a renormalized Fermi liquid. The universal scaling functions which we calculate could be useful in interpreting experiments on Ohmic two-state systems. In particular, since these functions are uniquely determined by the dissipation strength and level asymmetry, a single thermodynamic measurement allows α and ε to be extracted.
[1] A. M. Tsvelick and P. B. Wiegmann, Adv. Phys. 32, 453 (1983)
[2] T. A. Costi and G. Zaránd, preprint 1998