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Q: Fachverband Quantenoptik und Photonik

Q 40: Quantum Information: Quantum Computing

Q 40.3: Vortrag

Mittwoch, 10. März 2010, 17:00–17:15, F 128

Multiqubit Decoherence in Ion-trap Quantum Computation — •Thomas Monz¹, Philipp Schindler¹, Julio Barreiro¹, Michael Chwalla¹, Bill Coish^2,3, Markus Hennrich¹, and Rainer Blatt^1,4 — ¹Inst. f. Experimentalphysik, Innsbruck, AT — ²Inst. f. Quantum Computing, Waterloo, CA — ³Kavli Inst. f. Theoretical Physics, Santa Barbara, US — ⁴Inst. f. Quantenoptik u. Quanteninformation, Innsbruck, AT

In a linear string of calcium ions we have realised high-fidelity Schrödinger-Cat states with more than six qubits. Fidelities exceed 95% for up to 4 ions and 88% for six ions. These high fidelities allow to investigate decoherence of highly entangled quantum states in the presence of collective dephasing, the predominant decoherence source in ion-trap quantum computation. Modelling the noise to be stationary and Gaussian, we derive and experimentally confirm a model that predicts an exponential decay of the fidelity that scales with the power of N² with N being the number of qubits. Such a scaling behaviour has severe effects on the applicability of quantum computation in ion-trap based quantum computation and related fields such as quantum metrology.