Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 8: Posters Transport
TT 8.45: Poster
Friday, March 4, 2005, 14:00–18:00, Poster TU C
Decoherence during Two-Qubit Gates — •Markus J. Storcz, Frank Hellmann, Calin Hrelescu, and Frank K. Wilhelm — Physics Department and CeNS, Ludwig-Maximilians-Universität München, Theresienstr. 37, D-80333 München
Superconducting solid-state quantum bits (qubits) are promising candidates for the realization of a scalable quantum computer. However, they are limited by decoherence due to the many extra degrees of freedom of a solid-state system.
We investigate a system of two qubits in a setup that is typical for pseudospin solid-state qubits such as charge or flux systems. We evaluate the decoherence properties and gate quality factors (GQF) in the presence of a common and two uncorrelated baths coupling to an arbitrary mixture of σz and σx and evaluate the decoherence rates and GQF for non-ideal, i.e. non identical qubits, realized in experimental setups. We emphasize the importance of symmetries to minimize decoherence during a quantum gate operation and explore memory effects of the environment between gate pulses.
Moreover, we investigate a setup of a chain of superconducting qubits with capacitive (flux qubits) or inductive (charge qubits) nearest neighbor coupling. Errors due to 1/f noise, which is picked up by the coupling elements, are anticipated to be the dominating source of errors in this setup. We propose to encode the qubits into a Decoherence Free Subspace (DFS) that provides full protection against coupling errors.