Project A5

Control of Decoherence in Solid State Based Quantum Information Systems

PI: Prof. P. Hänggi

Decoherence constitutes a major obstacle in the realm of solid state systems that are designed for processing of quantum information. In this connection, the theory project A5 focuses on the realistic description of decoherence and optimizaton of coherence in complex superconducting circuits. In the same spirit, we have started to engage in the relatively new field of ultra-strongly coupled qubit-oscillator systems, about which little is known to date. The second main subject of the project deals with quantum transport processes and state preparation in charge and spin-hole qubits, being realized in driven quantum multidot systems. Our results aim at a better understanding of decoherence processes, particularly for the coherence phenomena occurring in solid state quantum information systems.

Project A5 is effectively tailored to support other experimental projects within the SFB 631. On the one hand, we preferably plan to develop generic models and descriptions of dissipation in the fields of dissipative circuit QED and driven quantum dots, which includes the development of the corresponding numerical tools. On the other hand, it is our sustained objective to explain concrete phenomena that do emerge from experiments but that are not understood beforehand. Here, we also provide our expertise, in particular with respect to Landau-Zener physics in time dependent driven quantum systems and decoherence phenomena. Depending on the specific experimental setups, we aim at deriving suitable generic quantum master equations (QME) for static and/or driven systems, including different possible ways of modeling the environment. Our findings enable us to gain insight in how coherence can be optimally controlled and what quantum states and parameter regimes turn out to be robust and thus preferable in order to perform efficient quantum information processing.


figure 1: Two-resonator circuit QED system, interacting with dissipative environments.



  1. "Time-resolved qubit readout via nonlinear Josephson inductance", Georg M Reuther, David Zueco, Peter Hänggi, and Sigmund Kohler, New J. Phys. 13, 093022 (2011)