Non-equilibrium dynamics of quantum-impurity systems close to quantum critical points

• Applicant: Professor Dr. Frithjof B. Anders
• Subject Area: Theoretical Condensed Matter Physics
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 210230633

The minimum of two qbits are required for coherent information exchange. A Fermionic environment coupled to the qbits causes not only dephasing but can also induce an effective spin-spin coupling via RKKY interaction. Another paradigm system for understanding dissipation of electrons in solids is the Bose-Fermi model where an additional dissipative Bosonic bath is coupled to the electronic subsystem. Both classes of systems can show quantum phase transitions. Little is known about the real-time dynamics out of equilibrium of such quantum systems close to the quantum phase transition.We plan to use the time-dependent numerical renormalization group approach to explore the dephasing and the information transfer between two quantum impurities close to the quantum phase transition. We are particularly interested in the question of thermalization in systems with residual impurity entropy. We want to investigate how the real-time dynamics changes when approaching the critical coupling. Do coherent oscillation prevail at the critical coupling which is strong enough to cause a change of ground state? We also will study the coherent control of the quantum information transfer by a periodic switching of the externally applied gate voltage.

• DFG Programme: Research Grants