Frankfurt 2006 – scientific programme

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MO: Molekülphysik

MO 53: Molecular Quantum Computing

MO 53.3: Talk

Thursday, March 16, 2006, 14:45–15:00, H12

Reducing Decoherence in Large Quantum Registers — •Marko Lovrić, Dieter Suter, and Hans Georg Krojanski — Universität Dortmund, Fachbereich Physik, 44221 Dortmund, Germany

Decoherence appears to be the main limiting factor for the implementation of large (and therefore powerful) quantum computers. While it is generally expected that quantum registers consisting of many qubits will decay faster than smaller ones, the decoherence rates had never been measured for systems with more than 2 qubits. To obtain such data we measure the decay of model quantum registers consisting of up to several thousand nuclear spins. These states can be created by solid-state nuclear magnetic resonance (NMR) techniques. Our results indicate that the decoherence rates increase with the system size, but not as fast as generally expected. For successful operation of a quantum computer it will be essential to reduce decoherence processes. Several approaches have been proposed for decoupling the system from its environment. We have tested several techniques on our model quantum registers and found that it was possible to extend the decoherence time by more than an order of magnitude, independent of the size of the quantum register.

[1] H. G. Krojanski and D. Suter, Phys. Rev. Lett. 93, 090501 (2004)