d-wave YBCO Josephson junctions in the quantum phase and charge limit

Thilo Bauch

Chalmers University of Technology, Göteborg

Tuesday, 10 February 2009, 15:15
Seminar room F

We present direct observation of macroscopic quantum properties in an all high critical temperature superconductor (HTS) d-wave Josephson junction. Although dissipation caused by low energy excitations is expected to strongly suppress quantum effects we demonstrate macroscopic quantum tunneling [1] and energy level quantization [2] in our d-wave Josephson junction. The results clearly indicate that the role of dissipation mechanisms in high temperature superconductors has to be revised, and may also have consequences for a new class of solid state "quiet" quantum bit with superior coherence time. Moreover we realized for the first time an all-HTS single electron tunneling transistor. This device is a powerful tool to probe the quasiparticle spectrum in HTS materials and should give valuable information about dissipation processes in HTS based quantum circuits.

[1] T. Bauch et al., Phys. Rev. Lett. 94, 087003 (2005).
[2] T. Bauch et al, Science 311, 57 (2006).