DPG Phi
Verhandlungen
Verhandlungen
DPG

Berlin 2008 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

TT: Fachverband Tiefe Temperaturen

TT 9: Transport: Quantum Coherence and Quantum Information Systems

TT 9.4: Talk

Monday, February 25, 2008, 15:00–15:15, H 2053

Coherent oscillations in a superconducting flux qubit without microwave pulses — •Stefano Poletto1, Jürgen Lisenfeld1, Alexander Lukashenko1, Maria Gabriella Castellano2, Fabio Chiarello2, Carlo Cosmelli3, Pasquale Carelli4, and Alexey V. Ustinov11Physikalisches Institut III, Universität Erlangen-Nürnberg, Germany — 2Istituto di Fotonica e Nanotecnologie del CNR, Roma, Italy — 3Dipartimento di Fisica and INFN, Universita’ di Roma La Sapienza, Italy — 4Universita’ degli Studi dell’Acquila, Italy

We report on observation of coherent oscillations in a superconducting flux qubit by using no microwave excitation but only nanosecond-long dc flux pulses. The investigated circuit is a double-SQUID consisting of a superconducting loop interrupted by a small dc-SQUID, which we control via two bias fluxes φc and φx. The potential energy profile of the qubit has the shape of a double well, where the flux φc controls the height of the barrier between the two minima and the flux φx changes the potential symmetry. The two computational states of the qubit are identified with the two energy minima and physically correspond to clockwise or anticlockwise circulating currents in the double-SQUID main loop. We observed coherent oscillations, in the frequency range between 8 and 20 GHz, induced by fast pulses of the control flux φc modulating the barrier between the two potential wells. The quantum dynamics that leads to this kind of oscillations is composed of a non-adiabatic and adiabatic evolution of the two lowest energy states.

100% | Mobile Layout | Deutsche Version | Contact/Imprint/Privacy
DPG-Physik > DPG-Verhandlungen > 2008 > Berlin