Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 4: Quantum Information I

Q 4.2: Talk

Monday, April 2, 2001, 16:00–16:15, Audimax

Ion trap quantum logic using microwave radiation — •Florian Mintert and Christof Wunderlich — Institut für Laser-Physik, Universität Hamburg, Jungiusstr. 9, 20355 Hamburg

Elements of quantum logic operations have been successfully demonstrated in experiments using ion traps, cavity quantum electrodynamics and in the case of nuclear magnetic resonance (NMR) even algorithms have been performed. Whereas quantum computation with nuclear spins in macroscopic ensembles can most likely not be extended beyond about 10 qubits (elementary registers) [1], ion traps do not suffer from limited scalability in principle [2], however they still pose formidable experimental challenges. Here we propose a method to implement quantum logic operations that combines experimental techniques and technology successfully demonstrated either in NMR experiments or with trapped ions: Applying an inhomogenenous magnetic field to a linear ion trap permits to individually address and coherently manipulate qubit states of ions confined in an electrodynamic trap using radiation in the microwave regime. An additional inhomogenenous magnetic field has two effects:
i) it shifts individual ionic hyperfine resonances serving as qubits, so that they can be individually addressed, and, ii) mediates the coupling between internal and external degrees of freedom even when microwave radiation is used for driving qubit transitions (i.e. when the Lamb-Dicke parameter is close to zero).

[1] J. A. Jones, Pre-print quant-ph/0002085 (2000).

[2] D. J. Wineland et al., J. Res. Natl. Inst. Stand. Technol. 103, 259 (1998).