Dresden 2006 – scientific programme

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TT: Tiefe Temperaturen

TT 26: Transport - Poster Session

TT 26.22: Poster

Wednesday, March 29, 2006, 14:30–18:30, P1

Implementation of two-cell flux qubits — •A. K. Feofanov, A. A. Abdumalikov, and A. V. Ustinov — Physikalisches Institut III, UniversitätErlangen-Nürnberg, Erlangen, Germany

The standard flux qubit implemented at Delft [1] consists of a superconducting loop with three Josephson junctions and features a double well potential at half frustration. Its limitation is that the barrier height cannot be changed without breaking the symmetry. An alternative device proposed by Yukon [2] is a two-cell flux qubit containing four junctions. One of the useful properties of Yukon’s qubit is that the barrier height can be controlled without violating the symmetry of the potential, which in turn permits implementation of geometric quantum computation using a Cirac-Zoller [3] type of bus. We have established a technological process for fabricating two-cell qubits based on sub-micron Al-AlO_x-Al Josephson tunnel junctions with a critical current density around 500 A/cm². We have also developed a design for reading out such qubits using inductive coupling. Results reflecting actual progress in this experiment will be presented.

[1] I. Chiorescu et al., Science 299, 1869 (2003)

[2] S.P. Yukon, Physica C 368, 320 (2002)

[3] J.I. Cirac and P. Zoller, Phys. Rev. Lett. 74, 4091 (1995)