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Q: Quantenoptik

Q 223: Quantum Information II

Q 223.3: Talk

Tuesday, March 5, 2002, 17:00–17:15, HS 11/215

Quantum computation in error correcting code spaces — •Michael Mussinger, Aldo Delgado, and Gernot Alber — Abteilung für Quantenphysik, Universität Ulm, D-89069 Ulm

An important requirement for quantum computation in real physical systems is the ability to preserve quantum coherence throughout a calculation. For this purpose one has to develop appropriate quantum error correcting codes and one has to develop methods for implementing a universal set of quantum gates so that these code spaces are not left at any time during a quantum calculation. Thus, in the general case of m logical qudits with d levels, it is necessary to span the complete group SU(d^m), at least approximately. This aim can be achieved, for example, with a set of quantum gates which is capable of generating any SU(d)-transformation on each single qudit and which is capable of entangling any two qudits. We present a universal set of gates which achieves this goal for our previously developed detected-jump correcting quantum codes [1]. Thus, with the help of these quantum gates it is possible to stabilize any quantum computation against spontaneous decay processes affecting distinguishable qubits.

This project is supported by the DFG within the SPP ‘Quanteninformationsverarbeitung’. A.D. acknowledges support by the DAAD.

[1] G. Alber, Th. Beth, Ch. Charnes, A. Delgado, M. Grassl and M. Mussinger, Phys. Rev. Lett. 86, 4402 (2001).