Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.25: Poster
Mittwoch, 24. März 2010, 14:00–18:00, Poster D1
Quantum Dissipation in Spin Systems: Spin-Boson Model and its Quantum Phase Transition — •André Winter and Heiko Rieger — Theoretische Physik, Universität des Saarlandes, Campus, 66123 Saarbrücken
Our interest is focused on quantum-dissipative effects in spin systems. These effects play a highly interesting role in several fields of physics, like the decoherence of qubits or charge transfer in donor-acceptor systems. Mainly, the spin-boson model, which describes a two-level system coupled to a bosonic bath with a spectral density J(ω) ∝ ωs will be discussed. We developed a new Monte Carlo algorithm to explore the quantum phase transition between the localized and delocalized phase of this model in the sub-Ohmic regime ( 0 < s < 1). The applied method, which is based on the path integral approach to Quantum Monte Carlo computations, works in continuous time and uses cluster updates of worldline-segments to investigate the quantum critical point effectively.
In addition, we are considering extensions within this framework like an alternative approach, where the bosonic environment is simulated explicitly or more general setups with multiple interacting spins.
[1] A. Winter, H. Rieger, M. Vojta, and R. Bulla, Phys. Rev. Lett. 102, 030601 (2009)