Dresden 2003 – scientific programme
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SYQI: Quantum information processing in condensed media
SYQI 2: Quantum information processing in condensed media II
SYQI 2.1: Talk
Monday, March 24, 2003, 15:30–15:45, HSZ/01
Decoherence and dissipation during a quantum XOR gate operation — •Michael Thorwart1 und Peter Hänggi2 — 1Department of NanoScience, Delft University of Technology, The Netherlands — 2Institut für Physik, Universität Augsburg
The dynamics of a generic quantum XOR gate involving two interacting qubits being coupled to an Ohmic harmonic bath is explored. By use of the formally exact quasiadiabatic propagator path integral technique we study the time-resolved evolution of this entangled two-qubit system in presence of time-dependent external fields. The quality of the XOR gate is monitored by four characteristic gate quantifiers. Two different types of errors for the XOR operation are modelled, i.e. bit-flip and phase errors. The dependence of the quantifiers on the various parameters is systematically investigated. Our main findings are that the gate quantifiers depend only very weakly on temperature, but are extremely sensitive to the bath interaction strength. Interestingly enough, however, the XOR gate deteriorates only weakly upon decreasing the interqubit coupling strength. This generic case study yields lower bounds on the quality of realistic XOR gate operations.
[1] M. Thorwart and P. Hänggi, Phys. Rev. A 65, 012309 (2002)