Regensburg 2004 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 25: FV-internes Symposium ”Superconducting Qubits and π-junctions”
TT 25.2: Fachvortrag
Donnerstag, 11. März 2004, 10:00–10:30, H20
Exploring quantum dynamics of Josephson vortices — •A.V. Ustinov1, A. Wallraff2, M.V. Fistul1, A. Kemp1, A. Lukashenko1, J. Lisenfeld1, and Y. Koval1 — 1Physikalisches Institut III, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany — 2Dept. Applied Physics, Yale University, New Haven, CT 06520, USA
Engineering of an energy profile for a vortex in a Josephson junction opens an opportunity for designing superconducting qubits based on spatially distinct quantum states. The energy profile for the vortex can be created, e.g., by making the junction of a particular geometrical shape and applying an external magnetic field. In our first experiments we have demonstrated novel vortex states in long Josephson junctions with complex engineered potentials [1]. Recently, for the first time, we have observed quantum tunneling of a single vortex in a long junction at temperatures below 100 mK and performed microwave spectroscopy of the vortex energy levels within a potential well [2]. The vortex behaves as a macroscopic quantum particle (with a spatial extent of several micrometers) which tunnels through a potential barrier created by a magnetic field applied to the junction. In agreement with theory, the separation between vortex energy levels is controlled by the field. We have also measured quantum dissociation of a vortex No-dqmoleculeNo-dq, consisting of a bound state of vortex and antivortex [3].
[1] A. Kemp et al. Phys.Stat.Sol.(b) 233, 472 (2002)
[2] A. Wallraff et al., Nature 425, 155 (2003)
[3] M.V. Fistul et al., to appear in Phys.Rev.Lett. (cond-mat/0307705)