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Symmetry breaking in the two channel Spin-Boson model
Benedikt Bruognolo (LMU)
06.12.2012 at 12:00
In the field of quantum information there is clear demand for a better understanding of open quantum systems, yet their numerical description can become extremely be challenging. Though the Numerical Renormalization Group (NRG) has proven to be a powerful tool in applications to fermionic system, this is only partly true for bosonic problems. When dealing with bosonic systems, that include a diverging number of states per bath oscillator, standard NRG calculations fail. Guo et al. (2012) presented an improved method based on the Density Matrix Renormalization Group (DMRG), which overcomes the problem of a diverging state space by variationally constructing a optimized boson basis on each site of the Wilson chain.
In my talk I will introduce this method and its application to the Spin-Boson model with two symmetrically coupled bosonic baths, focusing on the ground state phases and the phase transitions. Symmetry breaking in the numerics prevents Guo et al. (2012) from examining the phase boundary at zero external eld. Based on the symmetric
coupling of the two channels we explicitly include an abelian U(1) symmetry in the numerics. By that we manage to give a more accurate description of the phase transition. Preliminary results are shown.
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