Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 9: Transport: Quantum Coherence and Quantum Information Systems
TT 9.2: Vortrag
Montag, 25. Februar 2008, 14:15–14:30, H 2053
Probing the States of a High-Tc Intrinsic Phase Qubit — •X. Y. Jin, J. Lisenfeld, Y. Koval, A. V. Ustinov, and P. Müller — Institut für Physik der Kondensierten Materie, Universität Erlangen-Nürnberg
We report our results on fabricating and probing high-Tc intrinsic phase qubits. An intrinsic phase qubit is a superconducting ring made of a Bi2Sr2CaCu2O8+δ single crystal, intercepted by two intrinsic Josephson junction stacks. Macroscopic quantum tunneling was observed in these qubits, and the crossover temperature was around 600 mK. An intrinsic phase qubit is generally regarded as a multi-junction system, i.e. a system of many degrees of freedom in phase space. However, we discovered that as long as the two stacks are uniform, the intrinsic phase qubits behaves like a system with only two degrees of freedom, independent of the number of junctions in the stacks. Due to the large self-inductance, the potential of an intrinsic phase qubit has several minima in which the system can stay. In order to perform quantum operations, a technique using low-frequency microwaves is developed to assure that the system stays inside the chosen potential well.