The effect of noise correlations on the performance of quantum error-correcting and -avoiding methods

• Applicant: Privatdozent Dr. Rochus Klesse
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2007 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 31293481

The extraordinary power of quantum computation relies on the fact that a quantum-bit (qubit) register can be in the superposition of a very large number of classical computational states. At the same time, maintaining the quantum-coherence of such superpositions in the inevitable presence of external noise poses the main obstacle for the realization of quantum computers. For a small number of qubits this difficulty can be overcome by simply reducing the coupling to environmental degrees of freedom. With an increasing number of qubits it will, however, become extremely difficult to reach the required coherence in that way. It is therefore common opinion that any quantum computer of practically useful size will require schemes that actively or passively reduce the disturbing effects of external noise. In this project we will investigate to which extend the function of such schemes is impaired by noise correlations that are present in virtually all physical implementations of quantum computers. The results of this investigation will shed light on the open problem of whether or not large-scale quantum computation can be realized in principle.

• DFG Programme: Research Grants